Fetal imaging: executive summary of a joint Eunice Kennedy Shriver National Institute of Child Health and Human Development, Society for Maternal-Fetal Medicine, American Institute of Ultrasound in Medicine, American College of Obstetricians and Gynecologists, American College of Radiology, Society for Pediatric Radiology, and Society of Radiologists in Ultrasound Fetal Imaging workshop

Advancing fetal diagnosis and prognostication using comprehensive prenatal phenotyping and genetic testing

Prenatal diagnoses of congenital malformations have increased significantly in recent years with use of high-resolution prenatal imaging. Despite more precise radiological diagnoses, discussions with expectant parents remain challenging because congenital malformations are associated with a wide spectrum of outcomes. Comprehensive prenatal genetic testing has become an essential tool that improves the accuracy of prognostication. Testing strategies include chromosomal microarray, exome sequencing, and genome sequencing. The diagnostic yield varies depending on the specific malformations, severity of the abnormalities, and multi-organ involvement. The utility of prenatal genetic diagnosis includes increased diagnostic clarity for clinicians and families, informed pregnancy decision-making, neonatal care planning, and reproductive planning. Turnaround time for results of comprehensive genetic testing remains a barrier, especially for parents that are decision-making, although this has improved over time. Uncertainty inherent to many genetic testing results is a challenge. Appropriate genetic counseling is essential for parents to understand the diagnosis and prognosis and to make informed decisions. Recent research has investigated the yield of exome or genome sequencing in structurally normal fetuses, both with non-invasive screening methods and invasive diagnostic testing; the prenatal diagnostic community must evaluate and analyze the significant ethical considerations associated with this practice prior to generalizing its use. IMPACT: Reviews available genetic testing options during the prenatal period in detail. Discusses the impact of prenatal genetic testing on care using case-based examples. Consolidates the current literature on the yield of genetic testing for prenatal diagnosis of congenital malformations.

Antenatal screening for fetal structural anomalies - Routine or targeted practice?

Antenatal screening with ultrasound identifies fetal structural anomalies in 3-6% of pregnancies. Identification of anomalies during pregnancy provides an opportunity for counselling, targeted imaging, genetic testing, fetal intervention and delivery planning. Ultrasound is the primary modality for imaging the fetus in pregnancy, but magnetic resonance imaging (MRI) is evolving as an adjunctive tool providing additional structural and functional information. Screening should start from the first trimester when more than 50% of severe defects can be detected. The mid-trimester ultrasound balances the benefits of increased fetal growth and development to improve detection rates, whilst still providing timely management options. A routine third trimester ultrasound may detect acquired anomalies or those missed earlier in pregnancy but may not be available in all settings. Targeted imaging by fetal medicine experts improves detection in high-risk pregnancies or when an anomaly has been detected, allowing accurate phenotyping, access to advanced genetic testing and expert counselling.

An analytical cross-sectional study: determining gestational age using fetal clavicle length during the second trimester

PURPOSE

To investigate the correlation between fetal clavicle length and gestational age in pregnant patients from 14 and 27 weeks of gestation.

METHODS

This was a retrospective cross-sectional study of patients from 14 and 27 weeks of gestation. Ultrasonographic measurements such as abdominal circumference (AC), femur length (FL), humerus length (HL), clavicle length (CL), head circumference (HC), biparietal diameter (BPD), estimated fetal weight (EFW), and transverse cerebellum diameter (TCD) were made and compared.

RESULTS

A total of 552 patients were evaluated in our clinic and CL was measured properly and successfully in all fetuses. Fetal AC, FL, HL, CL, BPD, HC, EFW and TCD measurements were significantly and strongly correlated with gestational week, and Pearson's correlation values were 0.964, 0.965, 0.959, 0.965, 0.951, 0.917, 0.925, and 0.954, respectively (p < 0.001). In the regression analysis equation, gestational week = 0.894 + CL × 0.961.

CONCLUSION

There was a significant positive correlation between fetal CL (mm) and gestational week. We suggest that the 1 mm = 1 week rule can be used for patients with anomalies of the cerebellum and vermis, as well as for patients with unknown last menstrual period.

Shoulder dystocia in deliveries of neonates <3500 grams

OBJECTIVES

To study risk factors for shoulder dystocia (ShD) among women delivering <3500 g newborn.

METHODS

A retrospective case-control study of all term live-singleton deliveries during 2011-2019. Women with neonatal birthweight <3500 g were included. We compared cases of ShD to other deliveries by univariate and multivariable regression.

RESULTS

There were 79/41 092 (0.19%) cases of ShD among neonates <3500 g. In multivariable regression analysis, the following factors were independently associated with ShD; operative vaginal delivery (odds ratio [OR] 2.78; 95% confidence interval [CI]: 1.28-6.02, P = 0.009), vaginal birth after cesarean (VBAC, OR 2.74; 1.22-6.13, P = 0.010), sonographic abdominal circumference to biparietal diameter ratio (3.73 among ShD vs. 3.62, OR 1.35; 95% CI: 1.12-1.63, P = 0.001) and sonographic abdominal circumference to head circumference ratio (1.036 among ShD vs. 1.011, OR 3.04; 95% CI: 1.006-9.23, P = 0.049).

CONCLUSIONS

There is an association between operative vaginal delivery and ShD also in deliveries <3500 g. Importantly, the proportions between the fetal head and abdominal circumference are a better predictor of ShD than the newborn fetal weight and VBAC is associated with ShD.

Prevalence of anomalies on the routine mid-trimester ultrasound: 3172 consecutive cases by a single maternal-fetal medicine specialist

Introduction/Purpose

The routine mid-trimester fetal anatomy ultrasound (FAS) is offered to every pregnant woman and remains critical in the detection of structural fetal anomalies. Our study aimed to determine the prevalence of abnormalities on routine FAS performed by a single operator, who is an experienced sub-specialist in maternal-fetal medicine.

Methods

A retrospective analysis of all routine FAS performed a tertiary private obstetric ultrasound practice in metropolitan Sydney over a 7-year period, August 2015-July 2022. An advanced ultrasound protocol including detailed cardiac views was used in every case. Second opinion scans for suspected abnormalities were excluded. Fetal anomalies were classified into major and minor, based on the likely need for neonatal intervention.

Results

Among 14,908 obstetric ultrasound examinations, routine FAS were performed on 3172 fetuses by a single operator. More than 99% of women had screened low-risk for fetal aneuploidy. Structural anomalies were identified in 5% (157/3172) of fetuses; the prevalence of major anomalies was 1% (30/3172). Almost 60% of total anomalies were either cardiac or renal. No differences were identified in anomaly rates for singletons compared with twins (5.0% vs. 4.2%; P = 0.75). The prevalence of placenta previa and vasa previa was 10% and 0.1%, respectively.

Discussion

The prevalence of fetal anomalies on routine FAS by a single operator using a standardised protocol was higher in our practice (5%) than in previously published studies. Although most anomalies were minor, the rate of major abnormality was 1%.

Conclusion

The routine mid-trimester FAS remains an integral component of prenatal ultrasound screening.

Low lying placenta: natural course, clinical data, complications and a new model for early prediction of persistency

OBJECTIVE

To define the natural course and complications, and develop a model for predicting persistency when low-lying placenta (LLP) is detected early in pregnancy.

METHODS

This retrospective cohort study included women with LLP detected during an early anatomic scan performed at 13-16 weeks gestation. Additional transvaginal ultrasound exams were assessed for resolution at 22-24 weeks and 36-39 weeks. Patients were categorized as: Group 1-LLP resolved by the second-trimester scan, Group 2-LLP resolved by the third trimester, or Group 3-LLP persisted to delivery. Clinical and laboratory parameters, as well as maternal and neonatal complications, were compared. A linear support vector machine classification was used to define a prediction model for persistent LLP.

RESULTS

Among 236 pregnancies with LLP, 189 (80%) resolved by 22-24 weeks, 25 (10.5%) resolved by 36-39 weeks and 22 (9.5%) persisted until delivery. Second trimester hCG levels were higher the longer the LLP persisted (0.8 ± 0.7MoM vs. 1.13 + 0.4 MoM vs. 1.7 ± 1.5 MoM, adjusted p = .03, respectively) and cervical length (mm) was shorter (first trimester: 4.3 ± 0.7 vs. 4.1 ± 0.5 vs. 3.6 ± 1; adjusted p = .008; Second trimester: 4.4 ± 0.1 vs. 4.1 ± 1.2 vs. 3.8 ± 0.8; adjusted p = .02). The predictive accuracy of the linear support vector machine classification model, calculated based on these parameters, was 90.3%.

CONCLUSIONS

Persistent LLP has unique clinical characteristics and more complications compared to cases that resolved. Persistency can be predicted with 90.3% accuracy, as early as the beginning of the second trimester by using a linear support vector machine classification model.

Impact of Pelvic Rest Recommendations on Follow-Up and Resolution of Placenta Previa and Low-Lying Placenta

OBJECTIVE

To determine the rate of resolution of placenta previa and low-lying placenta (LLP) and the effect of pelvic rest recommendations on the timing of follow-up imaging.

METHODS

Retrospective review of pregnancies with previa/LLP detected on mid-trimester exam at our ultrasound unit from 2019 to 2021. LLP was defined as the lower edge of placenta located within 2 cm of the internal cervical os. Previa was defined as any portion of the placenta touching with the internal os. Demographics, placental location, activity restrictions, and delivery outcomes were analyzed. Timing of follow-up imaging was stratified by individuals advised and not advised pelvic rest.

RESULTS

Exactly 144 patients had previa and 266 had LLP on the mid-trimester exam with complete records. Previa resolution happened in 51.4% (74/144) of cases. Exactly 62% (46/74) of previa resolutions occurred by the 28-week ultrasound. Exactly 45% (65/144) of previa patients were advised pelvic rest. Most pelvic rest and non-pelvic rest patients had a 28-week scan. Even when clearance occurred, most patients in both groups had a repeat ultrasound at 32 weeks. Exactly 75% of LLP resolved by the 28-week scan, and the remainder by delivery. Exactly 12% (32/259) of LLP patients were advised pelvic rest.

CONCLUSION

Most societies recommend follow-up imaging at 32 weeks; however, our results suggest this may be done sooner and closer to 28 weeks. Pelvic rest did not affect timing of repeat imaging or delivery.

Polyhydramnios associated with congenital bilateral vocal cord paralysis: A case report

RATIONALE

Polyhydramnios may develop when the fetus cannot swallow amniotic fluid or the amount of fetal urine increases. Occasionally, unpredictable fetal abnormalities can be diagnosed postnatally. Bilateral vocal cord paralysis in the fetus may cause polyhydramnios, which could be related to impaired prenatal swallowing.

PATIENT CONCERN

A 36-year-old multipara underwent an emergent cesarean section because of polyhydramnios and active labor at 35 + 5 weeks of gestation and gave birth to a girl.

DIAGNOSIS

The neonate cried feebly and exhibited cyanosis as well as very weak response to stimuli. Chest retraction and stridor were observed. Laryngoscopic examination revealed no movement in both the vocal cords, and bilateral vocal cord paralysis was diagnosed.

INTERVENTIONS

When the baby was 40 days old, she underwent tracheostomy to alleviate the persistent stridor and oral feeding difficulties.

OUTCOMES

She was discharged at the age of 60 days while in the tracheostomy state.

LESSONS

Securing the airway of neonates with bilateral vocal cord paralysis, tracheoesophageal fistula, or muscular dystrophy, which can be detected after delivery in pregnant women with idiopathic polyhydramnios, is important. Therefore, pregnant women with idiopathic polyhydramnios must be attended to by experts, such as neonatologists, anesthesiologists, or otolaryngologists, who can secure the airway.

A Study of Clinical Characteristics, Demographic Characteristics, and Fetomaternal Outcomes in Cases of Placenta Previa: An Experience of a Tertiary Care Center

Background This study aimed to determine the demographic and clinical characteristics of pregnant women presenting with placenta previa and study the risk factors for the development of placenta previa, management strategies of associated complications, and maternal and perinatal outcomes. Methodology This prospective, observational study was conducted in the Department of Obstetrics and Gynaecology at Dr. S.N. Medical College, Umaid Hospital, Jodhpur, Rajasthan, India from May to October 2019. All patients with placenta previa were studied based on clinical presentation, management, and fetal and maternal outcomes. Results A total of 10,041 patients delivered during the study period. Of these, 61 were diagnosed with either minor placenta previa (placental edge within 2 cm, not covering the internal os) or major placenta previa (placental edge reaching or overlapping the internal os) for an incidence of 0.6%. The majority of the cases (65.57%) were in the age group of 20-29 years. Among the cases of placenta previa, 13.11% had previous cesarean sections, and 9.83% underwent previous dilatation and curettage (D & C) procedures. Moreover, 78.68% of the cases had ultrasound findings of the placenta partially or completely covering the os. Most patients were delivered by cesarean section (96.7%), and only 3.27% were delivered by vaginal delivery. Intensive care unit admission was required in 14.75% of the cases. The most common maternal complications observed were antepartum and postpartum hemorrhage, transfusion of blood and blood products, and long hospital stays. The preterm delivery rate was 62.30%, and 37.70% were term deliveries. Almost half of the babies (49.18%) were born with a birth weight of ≥2.5 kg, and 50.81% were in the low-birth-weight category. Apgar scores >7 at five minutes were observed in 85.3% of cases. Neonatal intensive care unit (NICU) admissions were 39.34%, and most babies recovered and shifted to the mother's side. The incidence of maternal mortality was 1.63%, and perinatal mortality was 9.83%. Conclusions The incidence of placenta previa was comparable to that reported in previous studies. Prevalence was more among younger women residing in rural areas who were unaware of regular antenatal check-ups. The main presenting symptom was painless vaginal bleeding, and ultrasonography was the most common diagnostic modality. Antepartum and postpartum hemorrhage was the most dreadful obstetric complications in cases of placenta previa, which affected maternal and fetal outcomes. Preterm and low birth weight were the main reason for NICU admissions. A team-based approach is required in the management of placenta previa cases.

Vaginal fluid index - The fifth amniotic pocket

OBJECTIVE

The forebag is a pocket of amniotic fluid preceding the fetal presenting part. Herein we describe the feasibility of transvaginal measurements of the forebag and assess its correlation with the standard amniotic fluid index (AFI).

METHODS

A prospective study was carried out between January 2019 and July 2020. Eligible cases were women with singletons, vertex presentation, and normal AFI at term. We assessed the implementation and acceptance of a novel process in the clinical practice setting. Feasibility was assessed by using transvaginal ultrasound to measure the three orthogonal planes of the forebag. The vaginal fluid index (VFI) was defined as the volume composite of the three orthogonal planes. Correlations of the forebag measurements with both AFI and maximal vertical pocket were then calculated.

RESULTS

In total, 292 out of 305 (95.7%) women were enrolled. All participants completed both transabdominal and transvaginal ultrasound, of which the vaginal pocket was demonstrated in 266 (91.1%) cases. We found significant correlations, in both nulliparas and multiparas, between the vaginal pocket measurements and the VFI to both the AFI and maximal vertical pocket measurements (R = 0.38, P < 0.001; R = 0.3, P < 0.001, respectively).

CONCLUSION

We introduced a new ultrasound variable, the VFI, with a high feasibility rate. This may provide invaluable information for future decision making around the time of delivery.

Prenatal detection of placenta previa and placenta accreta spectrum: Evaluation of the routine mid-pregnancy obstetric ultrasound screening between 2013 and 2017

OBJECTIVE

To examine the detection rate of placenta previa and placenta accreta spectrum (PAS) by routine mid-pregnancy obstetric ultrasound and to estimate risk factors and prevalence within this cohort.

METHODS

This was an observational cohort study with prospectively collected data. Women attending routine mid-pregnancy obstetric ultrasound at the Sahlgrenska University Hospital with a suspected cup-shaped placenta (cohort 1, n = 339) and women diagnosed with placenta previa or PAS (cohort 2, n = 227) were analyzed according to detection rate, risk factors, and prevalence.

RESULTS

The detection rates of placenta previa and PAS were 49% (98) and 25% (14), respectively. However, 216 (99%) women with placenta previa were diagnosed prenatally, as were 14 (50%) women with PAS. In vitro fertilization was identified as the strongest independent risk factor for placenta previa (odds ratio 6.96; 95% confidence interval 4.77-10.16, P < 0.001). Risk factors were present for all women with PAS. The prevalence of placenta previa was 44/10 000 deliveries, and for PAS, 5.6/10 000 deliveries.

CONCLUSION

The existing routine mid-pregnancy obstetric ultrasound screening showed low detection rate for placenta previa and PAS. Adding risk factors could improve the detection rate.

Reference ranges of fetal mandible measurements: Inferior facial angle, jaw index, mandible width/maxilla width ratio and mandible length in Thai fetuses at 15 to 23 weeks of gestation

Objectives

To determine the normal distribution of 1) inferior facial angles (IFA), 2) jaw index, 3) mandible width/maxilla width ratio (MD/MX ratio), and 4) mandible length (ML) in second trimester Thai fetuses.

Methods

A prospective study was performed between April 1 and October 31, 2020, at the Maternal-Fetal Medicine Unit of Songklanagarind Hospital. Transabdominal ultrasonography was performed on Thai singleton pregnant women at 15^0/7 to 23^6/7 weeks of gestation to measure IFA, jaw index, MD/MX ratio and ML. All women received standard antenatal care and were followed up until delivery. The exclusion criteria were multifetal gestation, congenital anomaly, chromosomal abnormality, fetal growth restriction, abnormal amniotic fluid volume, suspected abnormality of fetal mandible, maxilla or jaws based on the proposed criteria from previous studies and suspected neonatal structural or genetic abnormalities postnatally. Quantile regression was used to estimate changes in the median, 5th and 95th percentiles of each parameter across gestational ages and to generate formulas for predicting the 5th percentile value for each parameter.

Results

The results of 291 women were analyzed. Scatter plots and reference ranges of each parameter were generated. IFA, jaw index and ML values significantly increased, while the MD/MX ratio value significantly decreased, with increasing gestational age. The formulas calculated for predicting the 5th percentile value for each parameter were IFA = 55.12 + 0.045*(GA in days—136) jaw index = 37.272 + 0.01693*(GA in days—136) MD/MX ratio = exp(0.027–0.00110*(GA in days—136)) ML = 20.83 + 0.243*(GA in days—136).

Conclusions

The reference ranges and formulas to calculate the 5th percentile values of mandible parameters in Thai fetuses were developed.

Trial registration

This study has been reviewed and approved by the Thai Clinical Trials Registry with identification number TCTR20210602003.

Ultrasound and magnetic resonance imaging in the diagnosis of clinically significant placenta accreta spectrum disorders

OBJECTIVES

We aimed to assess the performance of ultrasound (US) and magnetic resonance imaging (MRI) signs for antenatal detection of placenta accreta spectrum (PAS) disorders in women with placenta previa (placental edge ≤2 cm from the internal uterine orifice, ≥26^0/7 weeks' gestation) with and without a history of previous Caesarean section.

METHODS

Single center prospective observational study. US suspicion of PAS was raised in the presence of obliteration of the hypoechoic space between uterus and placenta, interruption of the hyperechoic uterine-bladder interface and/or turbulent placental lacunae on color Doppler. All MRI studies were blindly evaluated by a single operator. PAS was defined as clinically significant when histopathological diagnosis was associated with at least one of: intrauterine balloon placement, compressive uterine sutures, peripartum hysterectomy, uterine or hypogastric artery ligature, uterine artery embolization.

RESULTS

A total of 39 women were included: 7/39 had clinically significant PAS. There were 6/18 cases of PAS with anterior placenta: hypoechoic space interruption and placental lacunae were the most sensitive sonographic signs (83%), while abnormal hyperechoic interface was the most specific (83%). On MRI, focal myometrial interruption and T2 intraplacental dark bands showed the best sensitivity (83%), bladder tenting had the best specificity (100%). 1/21 women with posterior placenta had PAS. There was substantial agreement between US and MRI in patients with anterior placenta (κ=0.78).

CONCLUSIONS

US and MRI agreement in antenatal diagnosis of clinically significant PAS was maximal in high-risk women. Placental lacunae on ultrasound scan and T2 intraplacental hypointense bands on MRI should trigger the suspicion of PAS.

Ritodrine versus salbutamol for external cephalic version

INTRODUCTION

Treatment with beta-agonist tocolytics preceding external cephalic version (ECV) attempt increases success rates. Most studies have focused on intravenously and orally administered beta-agonists, while other administration routes including intramuscularly (IM) and subcutaneously (SC) are understudied. We aimed to compare the efficacy of IM ritodrine to SC salbutamol given prior to ECV.

METHODS

A retrospective study of patients who underwent ECV between 1/2012 and 12/2019 at two medical centers. We compared patients undergoing ECV following IM ritodrine versus SC salbutamol. We matched the two groups by parity and placental location. Maternal, pregnancy, ECV procedure and neonatal characteristics were compared.

RESULTS

Overall, 601 women were included in each group. Median maternal age and amniotic fluid index (AFI) were lower in the Ritodrine group (27 vs. 32 years, p<0.001, 11 vs. 15 AFI cm, p<0.001, respectively). The median gestational age at ECV was higher in the Ritodrine group (380/7 vs. 370/7 weeks gestation). Success rate was higher in the Ritodrine group (71.7% vs. 63.8%, p=0.003). Vaginal delivery rate was higher in the Ritodrine group (70.7% vs. 60.1%, p<0.001). The number needed to treat to benefit was 10. In a multivariate analysis, Ritodrine was independently associated with higher ECV success rates as compared with Salbutamol (aOR 2.1, 95%CI 1.52-2.89).

CONCLUSIONS

Intramuscular ritodrine significantly improved the success rate of ECV compared to SC salbutamol, and both drugs were safe and acceptable before ECV.

Risk of preterm birth for placenta previa or low-lying placenta and possible preventive interventions: A systematic review and meta-analysis

OBJECTIVE

To investigate the risk of preterm birth in women with a placenta previa or a low-lying placenta for different cut-offs of gestational age and to evaluate preventive interventions.

SEARCH AND METHODS

MEDLINE, EMBASE, CENTRAL, Web of Science, WHO-ICTRP and clinicaltrials.gov were searched until December 2021. Randomized controlled trials, cohort studies and case-control studies assessing preterm birth in women with placenta previa or low-lying placenta with a placental edge within 2 cm of the internal os in the second or third trimester were eligible for inclusion. Pooled proportions and odds ratios for the risk of preterm birth before 37, 34, 32 and 28 weeks of gestation were calculated. Additionally, the results of the evaluation of preventive interventions for preterm birth in these women are described.

RESULTS

In total, 34 studies were included, 24 reporting on preterm birth and 9 on preventive interventions. The pooled proportions were 46% (95% CI [39 - 53%]), 17% (95% CI [11 - 25%]), 10% (95% CI [7 - 13%]) and 2% (95% CI [1 - 3%]), regarding preterm birth <37, <34, <32 and <28 weeks in women with placenta previa. For low-lying placentas the risk of preterm birth was 30% (95% CI [19 - 43%]) and 1% (95% CI [0 - 6%]) before 37 and 34 weeks, respectively. Women with a placenta previa were more likely to have a preterm birth compared to women with a low-lying placenta or women without a placenta previa for all gestational ages. The studies about preventive interventions all showed potential prolongation of pregnancy with the use of intramuscular progesterone, intramuscular progesterone + cerclage or pessary.

CONCLUSIONS

Both women with a placenta previa and a low-lying placenta have an increased risk of preterm birth. This increased risk is consistent across all severities of preterm birth between 28-37 weeks of gestation. Women with placenta previa have a higher risk of preterm birth than women with a low-lying placenta have. Cervical cerclage, pessary and intramuscular progesterone all might have benefit for both women with placenta previa and low-lying placenta, but data in this population are lacking and inconsistent, so that solid conclusions about their effectiveness cannot be drawn.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO https://www.crd.york.ac.uk/prospero/, identifier CRD42019123675.

Changes in prenatal testing during the COVID-19 pandemic

OBJECTIVE

The coronavirus disease 2019 (COVID-19) pandemic disrupted healthcare delivery, including prenatal care. The study objective was to assess if timing of routine prenatal testing changed during the COVID-19 pandemic.

METHODS

Retrospective observational cohort study using claims data from a regional insurer (Highmark) and electronic health record data from two academic health systems (Penn Medicine and Yale New Haven) to compare prenatal testing timing in the pre-pandemic (03/10/2018-12/31/2018 and 03/10/2019-12/31/2019) and early COVID-19 pandemic (03/10/2020-12/31/2020) periods. Primary outcomes were second trimester fetal anatomy ultrasounds and gestational diabetes (GDM) testing. A secondary analysis examined first trimester ultrasounds.

RESULTS

The three datasets included 31,474 pregnant patients. Mean gestational age for second trimester anatomy ultrasounds increased from the pre-pandemic to COVID-19 period (Highmark 19.4 vs. 19.6 weeks; Penn: 20.1 vs. 20.4 weeks; Yale: 18.8 vs. 19.2 weeks, all p < 0.001). There was a detectable decrease in the proportion of patients who completed the anatomy survey <20 weeks' gestation across datasets, which did not persist at <23 weeks' gestation. There were no consistent changes in timing of GDM screening. There were significant reductions in the proportion of patients with first trimester ultrasounds in the academic institutions (Penn: 57.7% vs. 40.6% and Yale: 78.7% vs. 65.5%, both p < 0.001) but not Highmark. Findings were similar with multivariable adjustment.

CONCLUSION

While some prenatal testing happened later in pregnancy during the pandemic, pregnant patients continued to receive appropriately timed testing. Despite disruptions in care delivery, prenatal screening remained a priority for patients and providers during the COVID-19 pandemic.

Impact of Using Abdominal Circumference Independently in the Diagnosis of Fetal Growth Restriction

OBJECTIVE

Society for Maternal-Fetal Medicine guidelines for diagnosing fetal growth restriction (FGR) have broadened the definition to include abdominal circumference (AC) <10^th percentile for gestational age (GA) regardless of estimated fetal weight (EFW). We aimed to compare the ability of three definitions of FGR to predict small for gestational age (SGA) neonates and adverse outcomes.

METHODS

We performed a secondary analysis of a prospective cohort of patients who underwent assessment of fetal growth between GA of 26 and 36 weeks. We compared three definitions of FGR: EFW <10^th percentile; AC <10^th percentile; either EFW or AC <10^th percentile. The primary outcome was successful prediction of neonatal SGA. Secondary outcomes included a composite adverse neonatal outcome (CANO). We further compared these definitions of FGR using area under receiver operative curves (AUC) to measure their discriminatory abilities.

RESULTS

About 1054 women met inclusion criteria. Ninety-one (8.6%) had EFW <10^th percentile, 122 (11.6%) had AC <10^th percentile, and 137 (12.9%) had either EFW or AC <10^th percentile. SGA was seen in 139 (13.2%); CANO was seen in 139 (13.2%). Ability for detecting neonatal SGA was significantly better when the definition included both EFW or AC <10^th percentile compared to either variable independently. The AUC were: 0.74, 0.73, 0.69; P = .0003. There was no statistical significance in ability for predicting CANO (AUC 0.51, 0.51, 0.50; P = .7447).

CONCLUSIONS

Addition of AC as a criterion for diagnosing FGR improves our ability to predict neonatal SGA compared to using EFW alone. All three definitions were poorly predictive of neonates at risk for adverse outcomes.

Analysis of maturation features in fetal brain ultrasound via artificial intelligence for the estimation of gestational age

BACKGROUND

Optimal prenatal care relies on accurate gestational age dating. After the first trimester, the accuracy of current gestational age estimation methods diminishes with increasing gestational age. Considering that, in many countries, access to first trimester crown rump length is still difficult owing to late booking, infrequent access to prenatal care, and unavailability of early ultrasound examination, the development of accurate methods for gestational age estimation in the second and third trimester of pregnancy remains an unsolved challenge in fetal medicine.

OBJECTIVE

This study aimed to evaluate the performance of an artificial intelligence method based on automated analysis of fetal brain morphology on standard cranial ultrasound sections to estimate the gestational age in second and third trimester fetuses compared with the current formulas using standard fetal biometry.

STUDY DESIGN

Standard transthalamic axial plane images from a total of 1394 patients undergoing routine fetal ultrasound were used to develop an artificial intelligence method to automatically estimate gestational age from the analysis of fetal brain information. We compared its performance-as stand alone or in combination with fetal biometric parameters-against 4 currently used fetal biometry formulas on a series of 3065 scans from 1992 patients undergoing second (n=1761) or third trimester (n=1298) routine ultrasound, with known gestational age estimated from crown rump length in the first trimester.

RESULTS

Overall, 95% confidence interval of the error in gestational age estimation was 14.2 days for the artificial intelligence method alone and 11.0 when used in combination with fetal biometric parameters, compared with 12.9 days of the best method using standard biometrics alone. In the third trimester, the lower 95% confidence interval errors were 14.3 days for artificial intelligence in combination with biometric parameters and 17 days for fetal biometrics, whereas in the second trimester, the 95% confidence interval error was 6.7 and 7, respectively. The performance differences were even larger in the small-for-gestational-age fetuses group (14.8 and 18.5, respectively).

CONCLUSION

An automated artificial intelligence method using standard sonographic fetal planes yielded similar or lower error in gestational age estimation compared with fetal biometric parameters, especially in the third trimester. These results support further research to improve the performance of these methods in larger studies.

Antepartum Fetal Surveillance: ACOG Practice Bulletin, Number 229

The goal of antepartum fetal surveillance is to reduce the risk of stillbirth. Antepartum fetal surveillance techniques based on assessment of fetal heart rate (FHR) patterns have been in clinical use for almost four decades and are used along with real-time ultrasonography and umbilical artery Doppler velocimetry to evaluate fetal well-being. Antepartum fetal surveillance techniques are routinely used to assess the risk of fetal death in pregnancies complicated by preexisting maternal conditions (eg, diabetes mellitus) as well as those in which complications have developed (eg, fetal growth restriction). The purpose of this document is to provide a review of the current indications for and techniques of antepartum fetal surveillance and outline management guidelines for antepartum fetal surveillance that are consistent with the best scientific evidence.

Pregnancy outcomes following laparoscopy for suspected adnexal torsion during pregnancy

OBJECTIVE

To evaluate pregnancy outcomes of women with surgically confirmed adnexal torsion (AT) as compared to those in whom AT was ruled out.

METHODS

A retrospective cohort study in a tertiary medical center. All pregnant women who underwent diagnostic laparoscopy due to suspected AT between 3/2011 and 4/2020 were included. We compared maternal, delivery and neonatal outcomes of both groups. We further compared women with confirmed AT to a control group of women who did not undergo laparoscopy during pregnancy.

RESULTS

During the study period, 112 women met the inclusion criteria. AT was confirmed in 93 cases (83.0%). Baseline characteristics did not differ between groups, excluding the rate of previous AT [5.4% in the torsion vs. 26.3% in the no-torsion group, odds ratio (OR) 0.15, 95% confidence interval (CI) 0.04-0.62, p = .004], and nulliparity rate (57.0% in the torsion vs. 31.6% in the no-torsion group, OR 2.41, 95%CI 1.004-8.21, p = .043). Pregnancies conceived by assisted reproductive technology were more common in the AT group compared to the no-AT group (46.2% vs. 10.5%, OR 7.21, 95%CI 1.59-33.45, p = .002). Miscarriage and stillbirth rates, gestational age at delivery, delivery characteristics and neonatal outcomes were favorable and did not differ between groups. Outcomes of pregnancies with confirmed AT did not differ from a control group of women who did not undergo laparoscopy during pregnancy.

CONCLUSION

Pregnancy outcomes among women who underwent laparoscopy for a suspected AT during pregnancy were reassuring, irrespective of the surgical findings and gestational week. Outcomes did not differ when compared to pregnant women who did not undergo laparoscopy.

SYNOPSIS

Maternal, fetal and neonatal outcomes among women who underwent laparoscopy for suspected adnexal torsion during pregnancy are reassuring, irrespective of the surgical findings and gestational week.

Risk of neural tube defects according to maternal body mass index: a systematic review and meta-analysis

INTRODUCTION

The aim of our systematic review and meta-analysis was to evaluate the risk of neural tube defects (NTDs) according to the pre-pregnancy body mass index.

MATERIALS AND METHODS

Electronic databases were searched (MEDLINE, EMBASE, Web of Sciences, Scopus, ClinicalTrial.gov, OVID, and Cochrane Library). Selection criteria included prospective and retrospective cohort studies reporting the prevalence of fetal NTDs in obese, overweight, and underweight pregnant women. Odds ratios (ORs) comparing risk among these subsets of pregnancies with normal weight mothers were determined with 95% confidence intervals (CI). The evaluated outcome was the association between maternal underweight, overweight, and obesity and the risk of NTDs.

RESULTS

We included ten studies published between 2000 and 2017, including underweight, overweight, and obese pregnant women with fetal NTD (cases) and pregnant women with recommended BMI with fetal NTD (controls). Compared with normal BMI women, obese mothers were at significantly higher risk of fetal NTDs (0.53 vs. 0.33%; OR 1.62 95% CI 1.32-1.99, p < .0001), while no difference for the risk of NTDs was found when comparing overweight (0.34 vs. 0.32%; OR 1.09 95% CI 0.92-1.3, p = .3) and underweight (0.65 vs. 0.24%; OR 1.34 95% CI 0.73-2.47, p = .34) with normal weight pregnant women.

DISCUSSION

Obese pregnant women are at significantly higher risk NTDs, while no significant difference has been found in overweight and underweight pregnant women. Key message Obese pregnant women are at significantly higher risk of NTDs, such as spina bifida compared with normal weight women. No difference was found when comparing overweight and underweight with normal weight women.

Outcome-based comparison of SMFM and ISUOG definitions of fetal growth restriction

OBJECTIVE

The recent international guidelines by the Society for Maternal-Fetal Medicine (SMFM) and the International Society of Ultrasound in Obstetrics and Gynecology (ISUOG) differ in their definitions of fetal growth restriction (FGR). Our aim was to compare the performance of the two definitions in predicting neonatal small-for-gestational age (SGA) and composite adverse neonatal outcome (ANO).

METHODS

This was a secondary analysis of data from a prospective study of women referred for fetal growth ultrasound examination between 26 + 0 and 36 + 6 weeks' gestation. The SMFM and ISUOG guidelines were used to define pregnancies with FGR. The SMFM definition of FGR is estimated fetal weight (EFW) or abdominal circumference (AC) < 10^th percentile. The ISUOG-FGR definition follows the Delphi consensus criteria and includes either EFW or AC < 3^rd percentile or EFW or AC < 10^th percentile combined with abnormal Doppler findings or a decrease in growth centiles. The primary outcome was the prediction of neonatal SGA, defined as birth weight < 10^th percentile, and a composite of ANO, which was defined as one or more of: Grade-III or -IV intraventricular hemorrhage, respiratory distress syndrome, neonatal death, cord blood pH < 7.1, seizures and admission to the neonatal intensive care unit. Test characteristics (sensitivity, specificity, positive predictive value (PPV), negative predictive value and positive (LR+) and negative likelihood ratios) and area under the receiver-operating-characteristics curve were determined. The association between FGR detected by each definition and selected adverse outcomes was assessed using logistic regression analysis.

RESULTS

Of the 1054 pregnancies that met the inclusion criteria, 137 (13.0%) and 55 (5.2%) were defined as having FGR by the SMFM and ISUOG definitions, respectively. Composite ANO and SGA neonate each occurred in 139 (13.2%) pregnancies. For the prediction of neonatal SGA, the SMFM-FGR definition had a higher sensitivity (54.7%) than did the ISUOG definition (28.8%). The ISUOG-FGR definition had higher specificity (98.4% vs 93.3%), LR+ (18.0 vs 8.2) and PPV (72.7% vs 55.5%) than did the SMFM definition for the prediction of a SGA neonate. The SMFM- and ISUOG-FGR definitions had similarly poor performance in predicting composite ANO, with sensitivities of 15.1% and 10.1%, respectively.

CONCLUSIONS

The SMFM definition of FGR is associated with a higher detection rate for SGA neonates but at the cost of some reduction in specificity. The ISUOG-FGR definition has a higher specificity, LR+ and PPV for the prediction of neonatal SGA. Both definitions of FGR performed poorly in predicting a composite ANO. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Ultrasound Core Laboratory for the Household Air Pollution Intervention Network Trial: Standardized Training and Image Management for Field Studies Using Portable Ultrasound in Fetal, Lung, and Vascular Evaluations

Ultrasound Core Laboratories (UCL) are used in multicenter trials to assess imaging biomarkers to define robust phenotypes, to reduce imaging variability and to allow blinded independent review with the purpose of optimizing endpoint measurement precision. The Household Air Pollution Intervention Network, a multicountry randomized controlled trial (Guatemala, Peru, India and Rwanda), evaluates the effects of reducing household air pollution on health outcomes. Field studies using portable ultrasound evaluate fetal, lung and vascular imaging endpoints. The objective of this report is to describe administrative methods and training of a centralized clinical research UCL. A comprehensive administrative protocol and training curriculum included standard operating procedures, didactics, practical scanning and written/practical assessments of general ultrasound principles and specific imaging protocols. After initial online training, 18 sonographers (three or four per country and five from the UCL) participated in a 2 wk on-site training program. Written and practical testing evaluated ultrasound topic knowledge and scanning skills, and surveys evaluated the overall course. The UCL developed comprehensive standard operating procedures for image acquisition with a portable ultrasound system, digital image upload to cloud-based storage, off-line analysis and quality control. Pre- and post-training tests showed significant improvements (fetal ultrasound: 71% ± 13% vs. 93% ± 7%, p < 0.0001; vascular lung ultrasound: 60% ± 8% vs. 84% ± 10%, p < 0.0001). Qualitative and quantitative feedback showed high satisfaction with training (mean, 4.9 ± 0.1; scale: 1 = worst, 5 = best). The UCL oversees all stages: training, standardization, performance monitoring, image quality control and consistency of measurements. Sonographers who failed to meet minimum allowable performance were identified for retraining. In conclusion, a UCL was established to ensure accurate and reproducible ultrasound measurements in clinical research. Standardized operating procedures and training are aimed at reducing variability and enhancing measurement precision from study sites, representing a model for use of portable digital ultrasound for multicenter field studies.

Prediction of Large-for-Gestational-Age Neonates by Different Growth Standards

OBJECTIVE

Compare the accuracy of the Hadlock, the NICHD, and the Fetal Medicine Foundation (FMF) charts to detect large-for-gestational-age (LGA) and adverse neonatal outcomes (as a secondary outcome).

METHODS

This is a secondary analysis from a prospective study that included singleton non-anomalous gestations with growth ultrasound at 26-36 weeks. LGA was suspected with estimated fetal weight > 90^th percentile by the NICHD, FMF, and Hadlock charts. LGA was diagnosed with birth weight > 90^th percentile. We tested the performance of these charts to detect LGA and adverse neonatal outcomes (neonatal intensive care unit admission, Ph < 7.1, Apgar <7 at 5 minutes, seizures, and neonatal death) by calculating the area under the curve, sensitivity, specificity, positive predictive value, and negative predictive value.

RESULTS

Of 1054 pregnancies, 123 neonates (12%) developed LGA. LGA was suspected in 58 (5.5%) by Hadlock, 229 (21.7%) by NICHD standard, and 231 (22%) by FMF chart. The NICHD standard (AUC: .79; 95% CI: .75-.83 vs. AUC .64; 95%CI: .6-.68; p = < .001) and FMF chart (AUC: .81 95% CI: .77-.85 vs. AUC .64; 95%CI: .6-.68; p = < .001) were more accurate than Hadlock. The FMF and NICHD had higher sensitivity (77.2 vs. 72.4 vs. 30.1%) but Hadlock had higher specificity for LGA (97.5 vs. 88.5 vs. 85.4%). All standards were poor predictors for adverse neonatal outcomes.

CONCLUSIONS

The NICHD and the FMF standards may increase the detection rate of LGA in comparison to the Hadlock chart. However, this may increase obstetrical interventions.

Deep learning model for predicting gestational age after the first trimester using fetal MRI

OBJECTIVES

To evaluate a deep learning model for predicting gestational age from fetal brain MRI acquired after the first trimester in comparison to biparietal diameter (BPD).

MATERIALS AND METHODS

Our Institutional Review Board approved this retrospective study, and a total of 184 T2-weighted MRI acquisitions from 184 fetuses (mean gestational age: 29.4 weeks) who underwent MRI between January 2014 and June 2019 were included. The reference standard gestational age was based on the last menstruation and ultrasonography measurements in the first trimester. The deep learning model was trained with T2-weighted images from 126 training cases and 29 validation cases. The remaining 29 cases were used as test data, with fetal age estimated by both the model and BPD measurement. The relationship between the estimated gestational age and the reference standard was evaluated with Lin's concordance correlation coefficient (ρc) and a Bland-Altman plot. The ρc was assessed with McBride's definition.

RESULTS

The ρc of the model prediction was substantial (ρc = 0.964), but the ρc of the BPD prediction was moderate (ρc = 0.920). Both the model and BPD predictions had greater differences from the reference standard at increasing gestational age. However, the upper limit of the model's prediction (2.45 weeks) was significantly shorter than that of BPD (5.62 weeks).

CONCLUSIONS

Deep learning can accurately predict gestational age from fetal brain MR acquired after the first trimester.

KEY POINTS

• The prediction of gestational age using ultrasound is accurate in the first trimester but becomes inaccurate as gestational age increases. • Deep learning can accurately predict gestational age from fetal brain MRI acquired in the second and third trimester. • Prediction of gestational age by deep learning may have benefits for prenatal care in pregnancies that are underserved during the first trimester.

Detection of small for gestational age in preterm prelabor rupture of membranes by Hadlock versus the Fetal Medicine Foundation growth charts

Objective

The primary outcome was to compare the diagnostic accuracy of neonatal small for gestational age (SGA) by the Hadlock and Fetal Medicine Foundation (FMF) charts in our cohort, followed by the ability to predict composite severe neonatal outcomes (SNO) in pregnancies with preterm prelabor rupture of membranes (PPROM).

Methods

This study was a secondary analysis of a prospective cohort of pregnancies with PPROM from 2015 to 2018, from 23 to 36 completed weeks of gestation. Sensitivity, specificity, and positive and negative predictive values for the primary and secondary outcomes of the Hadlock and FMF fetal charts were calculated. The discriminatory ability of each chart was compared using the area under the receiver’s operating curves of clinical characteristics.

Results

Of the 106 women who met the inclusion criteria, 48 (45%) were screened positive using the FMF fetal growth chart and 22 (21%) were screened positive using the Hadlock chart. SGA was diagnosed in 12 infants (11%). Both fetal growth charts had comparable diagnostic accuracies and were statistically significant predictors of SGA (Hadlock: area under the receiver operating characteristic curves [AUC], 0.76, risk ratio [RR], 7.6, 95% confidence interval [CI], 2.5–23; and FMF: AUC, 0.76 RR, 13.3 95%CI 1.8–99.3). Both growth standards were poor predictors of SNO.

Conclusion

The Hadlock and FMF fetal growth charts have a similar accuracy to predict SGA in pregnancies complicated by PPROM. The FMF fetal growth chart may result in a 2-fold increase in positive screens, potentially increasing fetal surveillance.

Lung ultrasound for early surfactant treatment: Development and validation of a predictive model

AIM

To develop and validate a feasible predictive model for early surfactant treatment in very preterm infants (VPI) admitted with respiratory distress syndrome (RDS).

METHODS

Preterm infants less than 32 weeks of gestation with RDS and stabilized with noninvasive ventilation in delivery room were recruited (January 2018-April 2020). Clinical data, chest X-ray (CXR) score, respiratory support, oxygen saturation/fraction of inspired oxygen ratio (SF ratio), lung ultrasound (LUS) score, and diaphragmatic thickening fraction (DTF) were recorded at 60-120 min of life. Oxygen threshold for surfactant administration was fraction of inspired oxygen more than 30%; ultrasound findings were blinded. Logistic regression models using a stepwise selection of variables were developed in the derivation cohort. Coefficients from these models were applied to the validation cohort and a diagnostic performance was calculated.

RESULTS

A total of 144 VPI with a mean gestational age of 28.7 ± 2.2 weeks were included (94 into the derivation cohort, 50 into the validation cohort); 37 required surfactant treatment (25.7%). Gestational age, SF ratio, LUS score, CXR score, and Silverman score were related to surfactant administration (R²  = .823). Predictors included in the final model for surfactant administration were SF ratio and LUS score (R²  = .783) with an area under the receiver operating characteristic (AUC) = 0.97 (95% confidence interval [CI]: 0.93-1.00) in the derivation cohort and an AUC = 0.95 (95% CI: 0.85-0.99) in the validation cohort. By applying our predictive model, 26 patients (70.2%) would have been treated with surfactant earlier than 2 h of life.

CONCLUSION

The predictive model showed a high diagnostic performance and could be of value to optimize early respiratory management in VPI with RDS.

Prediction of adverse neonatal outcome among newborns born through meconium-stained amniotic fluid

OBJECTIVE

To study maternal and intrapartum factors associated with adverse neonatal outcome in deliveries complicated by meconium-stained amniotic fluid (MSAF).

METHODS

A retrospective cohort study of all women with singleton gestations undergoing trial of labor with MSAF during 2011-2020. Deliveries with adverse neonatal outcome were compared with deliveries without.

RESULTS

Overall, 11 329 were included; 376 (3.3%) neonates were diagnosed with adverse neonatal outcomes. Multivariable regression analysis underlined the following factors as independently associated with composite adverse neonatal outcome: pregestational diabetes (odds ratio [OR] 3.21, 95% confidence interval [CI] 1.09-9.43, P = 0.031), polyhydramnios (OR 2.14, 95% CI 1.33-3.44, P = 0.002), fever (OR 2.52, 95% CI 1.67-3.80, P < 0.001), and amnioinfusion (OR 1.73, 95% CI 1.24-2.2438, P = 0.003). When 0, 1, 2, and 3 of the independent risk factors identified were present, the rates of adverse neonatal outcome were 2.9%, 5.5%, 10.0%, and 100%, respectively.

CONCLUSION

The current study's results suggest that special attention should be payed to deliveries complicated by MSAF and with any of the following factors-polyhydramnios, intrapartum fever, amnioinfusion, and pregestational diabetes.

Applicability of ultrasonography for detection of marginal sinus placenta previa

This study aimed to examine whether marginal sinus placenta previa, defined as when the marginal sinus just reaches the internal cervical os and placental parenchyma might be >2 cm from the internal cervical os, can be diagnosed using ultrasonography (US). We identified the placenta previa cases that underwent both US and magnetic resonance imaging (MRI) between April 2010 and December 2018 at our institution. The diagnostic discrepancies for marginal sinus placenta previa between US and MRI were examined retrospectively. Of the 183 cases of placenta previa, 28 (15.3%) cases were diagnosed as marginal sinus placenta previa using MRI. Among them, 18 cases (64.3%) could also be diagnosed using US. The sensitivity and specificity of the diagnosis of marginal sinus placenta previa using US were 64.3% and 92.9%, respectively. A change in US diagnosis occurred in 10 (35.7%) cases, all of which were diagnosed with low-lying placenta previa or marginal placenta previa and did not develop any serious miserable obstetrical outcomes. In conclusion, the diagnostic accuracy of US for detecting marginal sinus placenta previa was not significant. MRI examination may be required to accurately categorize the types of placenta previa.

Screening for Fetal Chromosomal Abnormalities: ACOG Practice Bulletin, Number 226

Prenatal testing for chromosomal abnormalities is designed to provide an accurate assessment of a patient's risk of carrying a fetus with a chromosomal disorder. A wide variety of prenatal screening and diagnostic tests are available; each offers varying levels of information and performance, and each has relative advantages and limitations. When considering screening test characteristics, no one test is superior in all circumstances, which results in the need for nuanced, patient-centered counseling from the obstetric care professional and complex decision making by the patient. Each patient should be counseled in each pregnancy about options for testing for fetal chromosomal abnormalities. It is important that obstetric care professionals be prepared to discuss not only the risk of fetal chromosomal abnormalities but also the relative benefits and limitations of the available screening and diagnostic tests. Testing for chromosomal abnormalities should be an informed patient choice based on provision of adequate and accurate information, the patient's clinical context, accessible health care resources, values, interests, and goals. All patients should be offered both screening and diagnostic tests, and all patients have the right to accept or decline testing after counseling.The purpose of this Practice Bulletin is to provide current information regarding the available screening test options available for fetal chromosomal abnormalities and to review their benefits, performance characteristics, and limitations. For information regarding prenatal diagnostic testing for genetic disorders, refer to Practice Bulletin No. 162, Prenatal Diagnostic Testing for Genetic Disorders. For additional information regarding counseling about genetic testing and communicating test results, refer to Committee Opinion No. 693, Counseling About Genetic Testing and Communication of Genetic Test Results. For information regarding carrier screening for genetic conditions, refer to Committee Opinion No. 690, Carrier Screening in the Age of Genomic Medicine and Committee Opinion No. 691, Carrier Screening for Genetic Conditions. This Practice Bulletin has been revised to further clarify methods of screening for fetal chromosomal abnormalities, including expanded information regarding the use of cell-free DNA in all patients regardless of maternal age or baseline risk, and to add guidance related to patient counseling.

Follow-up ultrasound in second-trimester low-positioned anterior and posterior placentae: prospective cohort study

OBJECTIVES

The majority of cases of placenta previa or a low-lying placenta in the second trimester will have a normal placental position in the third trimester. The aim of this study was to assess the accuracy of the distance between the placenta and the internal os of the cervix (IOD) in the second trimester for the prediction of third-trimester low-positioned placenta, and to define a cut-off value at which all cases of third-trimester low-positioned placenta are identified.

METHODS

This was a prospective cohort study including women undergoing a transvaginal ultrasound examination between 18 and 24 weeks' gestation who had a low-positioned placenta, defined as an IOD of < 20 mm. Low-positioned placenta included placenta previa, defined as a placenta covering the internal os of the cervix, and a low-lying placenta, defined as a placenta lying near to (within 20 mm) but not overlying the internal os. All women were re-evaluated in the third trimester. Relative risks for a low-positioned placenta in the third trimester were calculated for women with placenta previa vs a low-lying placenta, posterior vs anterior placenta and positive vs negative history of Cesarean section. Multilevel likelihood ratios for ranges of IOD in the prediction of a low-positioned placenta in the third trimester were calculated separately for anteriorly and posteriorly located placentae. Corresponding receiver-operating-characteristics curves were constructed.

RESULTS

In total, 958 women were included in the study. In the second trimester, placentae were more frequently located on the posterior side (62.0%) than on the anterior side (38.0%). In the third trimester, 48/958 (5.0%) placentae persisted as a low-positioned placenta. Women with placenta previa in the second trimester had a higher risk of a low-positioned placenta in the third trimester than did those with a low-lying placenta in the second trimester (37/181 (20.4%) vs 11/777 (1.4%); relative risk (RR), 17.9 (95% CI, 8.9-36.0)). Women with a posterior placenta had a higher risk of a low-positioned placenta in the third trimester than did those with an anterior placenta (38/594 (6.4%) vs 10/364 (2.7%); RR, 2.4 (95% CI, 1.2-4.9)), as did women with a history of Cesarean section compared with those without such a history (14/105 (13.3%) vs 34/853 (4.0%); RR, 3.7 (95% CI, 1.9-7.2)). The cut-off value of IOD in the second trimester to identify all cases of an abnormally located placenta in the third trimester was 15.5 mm for posteriorly located placentae, while for anteriorly located placentae the IOD cut-off was lower, namely -4.5 mm, representing a 4.5-mm overlap of the placental edge over the internal os of the cervix.

CONCLUSIONS

With incorporation of a safety margin of 5 mm and ensuring that all women with placenta previa undergo a follow-up scan, we recommend lowering the IOD cut-off value for follow-up in cases of an anterior low-positioned placenta from 20 to 5 mm, which would decrease the number of unnecessary follow-up ultrasound examinations without missing any high-risk women. © 2019 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

ACR Appropriateness Criteria® Second and Third Trimester Vaginal Bleeding

Vaginal bleeding can occur throughout pregnancy with varied etiologies. Although history and physical examination can identify many etiologies, imaging, in particular ultrasound (US), is the backbone of current medical practice. US pregnant uterus transabdominal, US pregnant uterus transvaginal, and US duplex Doppler velocimetry are usually appropriate for the evaluation of women with painless vaginal bleeding, those with painful vaginal bleeding, and also for those with second or third trimester vaginal bleeding with suspicion of or known placenta previa, low-lying placenta, or vasa previa. US cervix transperineal may be appropriate for those with painless or painful vaginal bleeding but is usually not appropriate for second or third trimester vaginal bleeding with suspicion of or known placenta previa, low-lying placenta, or vasa previa. Because the outcome of pregnancies is unequivocally related to the specific etiology of the vaginal bleeding, knowledge of imaging results directly informs patient management to optimize the outcome for mother and fetus. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Peri-implantation cytokine profile differs between singleton and twin IVF pregnancies

PROBLEM

It is unknown whether maternal cytokine production differs between twin and singleton gestations in the implantation phase. A difference in maternal serum cytokine concentrations in twins would imply a dose-response to the invading embryos, as opposed to a general immune reaction.

METHOD OF STUDY

A prospective longitudinal cohort of women aged 18-45 at an academic fertility center undergoing in vitro fertilization and embryo transfer (IVF-ET) underwent routine collection of serial serum samples starting 9 days after ET and then approximately every 48 hours thereafter. Cryopreserved aliquots of these samples were assayed for interleukin-10 (IL-10), tumor necrosis factor-alpha (TNF-α), and C-X-C motif chemokine ligand 10 (CXCL10) using the SimplePlex immunoassay platform. Pregnancies were followed until delivery. Serial measures of serum concentrations of IL-10, CXCL10, and TNF-α in singleton or di-di twin pregnancies from 9 to 15 days after IVF-ET were compared.

RESULTS

Maternal serum levels of CXCL10 are significantly lower in women with di-di twin pregnancies in early implantation compared to those with singleton gestation (day 9-11, P = .02). Serum levels of TNF-α and IL-10 were comparable at all studied time points (P > .05).

CONCLUSION

Maternal serum levels of CXCL10 are significantly lower in the earliest implantation phase in di-di twins compared to singleton conceptions. Given the known anti-angiogenic role of CXCL10, we hypothesize that lower CXCL10 levels in twin implantations allow an environment that is conducive for the greater vascularization required for the establishment of dual placentation in di-di twins.

Use of Fetal Magnetic Resonance Imaging After Sonographic Identification of Major Structural Anomalies

OBJECTIVES

To characterize population-based use of fetal magnetic resonance imaging (MRI) incorporating recent American College of Radiology (ACR)-Society of Perinatal Radiologists (SPR) guidelines about fetal anomalies for which MRI may provide valuable additional information when sonography is limited.

METHODS

We conducted a retrospective review of nonreferred singleton pregnancies that received prenatal care and had prenatal sonographic diagnosis of 1 or more major structural anomalies at our hospital between January 2010 and May 2018. Detailed sonography was performed in all anomaly cases. Fetal anomaly information was obtained from a prospectively maintained database, and medical records were reviewed to determine the rationale for why MRI was or was not performed, according to the indication.

RESULTS

A total of 104,597 singleton pregnancies underwent sonographic assessments of anatomy at our institution during the study period. Major structural anomalies were identified in 1650 (1.6%) of these pregnancies. Potential indications for fetal MRI per ACR-SPR guidelines were identified in 339 cases. However, fetal MRI was performed in only 253 cases, 15% of those with major anomalies and 75% with a potential indication. Magnetic resonance imaging was not performed in 41 (20%) of identified pregnancies because of an improved prognosis on serial sonography (36), because of a poor prognosis (3), or because it would not alter management (2).

CONCLUSIONS

Fetal MRI was used in 15% of those pregnancies with prenatal diagnosis of a major structural anomaly. This amounted to fewer than 0.3% of singleton deliveries. Judicious application of ACR-SPR guidelines in the context of serial sonography results in a relatively small number of fetal MRI examinations in a nonreferred population.

[Genital abnormalities: Contextualization of a neglected area in prenatal diagnosis]

OBJECTIVE

To reflect on how the area of genital abnormalities has fallen behind in prenatal diagnosis.

METHODS

Based on the thesis that prenatal diagnosis of genital abnormalities has scarcely developed, a comparison with other areas of prenatal diagnosis and with its postnatal counterpart is presented; different explanations for this situation are examined; and a reflection is presented on ways to expand this field of knowledge.

CONCLUSIONS

Compared to other disciplines, prenatal diagnosis of genital abnormalities finds itself lagging behind in terms of diagnostic tools, management protocols and scientific literature. Potential causes include a perception of low prevalence and limited importance, or exploration challenges. Integration of current knowledge, together with the acquisition of the appropriate tools and translation to clinical medicine, would be a way to make this discipline stronger.

Which second trimester placenta previa remains a placenta previa in the third trimester: A prospective cohort study

OBJECTIVE

The far majority of women with a placenta previa in the second trimester will no longer have a placenta that overlies the internal os in the third trimester. Women with a placenta previa in the third trimester are at risk for complication such as preterm birth and blood loss. Four counselling purposes we aim to identify which women with a second trimester placenta previa have a low-risk and a high-risk for persistence of the placenta previa.

STUDY DESIGN

A prospective cohort study of women with a placenta previa in the second trimester between 2014 and 2019. The odds for having a placenta previa in the third trimester were calculated for different baseline characteristics. Multilevel likelihood ratios for ranges of the placenta overlying the internal os in the second trimester and the corresponding ROC curve were calculated to identify the optimal cut-off values.

RESULTS

We included 313 women with a placenta previa in the second trimester. The placenta was more frequently located on the posterior wall (62 %) than on the anterior wall (38 %). At evaluation in the third trimester, 37 women (14 %) still had a placenta previa. Women with a larger distance of the placenta overlying the internal os, women having a previous cesarean delivery and women after a conception with assisted reproductive technique had a significant higher risk of placenta previa persistence (p-values <0.001). Women with a placenta overlying less than 14 mm can be considered as low-risk, indicated by a likelihood ratio of 0. Women with a placenta with more than 55 mm overlap can be considered as high-risk, indicated a the likelihood ratio of ∞.

CONCLUSION

The majority of the second trimester placenta previa will no longer overly the internal os in the third trimester. Placenta previa persistence is associated with the distance overlying the internal os, a previous cesarean delivery and assisted reproductive techniques. In the second trimester, women can be identified as low-risk and high-risk for persistence of placenta previa. This can be used for risk stratification, counselling and individualized care for women with a second trimester placenta previa.

Sonographic measure techniques of fetal penile length

Postnatal penile length is a reliable, standardized, and widely used marker for the diagnosis of genitourinary pathology, as well as genetic and hormonal disorders. In contrast, prenatal diagnosis has not been developed equally and there is a lack of relevant literature. Our objective is to review the studies on fetal penile length, and apply findings to clinical practice. Although the most used technique is the outer penile length, there is no consensus regarding the appropriate technique for prenatal measurement. Several reports have provided reference data with high correlation. However, important issues like poor correlation with post-natal measures or presence of confounding variables are still present. Diagnosis of both a micropenis and macropenis can indicate related pathologies, and this information may benefit parental counseling and facilitate fetal management. Therefore, it is necessary to carry out prospective studies that provide reliable normative data.

Optimal timing of the second trimester fetal ultrasound in the obese gravida

OBJECTIVES

Obesity is increasingly prevalent in the obstetric patient population, becoming one of the most commonly occurring risk factors in obstetric practice. Obesity has implications for maternal and fetal morbidity; in fact, some data suggest it is associated with higher rates of fetal anomaly. Coincident with this, maternal obesity poses an inherent challenge for ultrasound quality. The objective of this study is to investigate the relationship between ultrasound completion rates and advancing gestational age in obese gravidas, and to help identify an ideal gestational age to perform the second trimester ultrasound for fetal evaluation in the obese patient population. We hypothesized that in the obese patient, the odds of a completed scan would increase with each gestational age week, as fetal size increases.

METHODS

This is a retrospective cohort study at a single tertiary care center. Inclusion criteria were pregnant women with BMI greater than 30 who had second trimester fetal ultrasound and delivery at our institution. Exclusion criteria were pregnancies without documented BMI, ultrasound not performed between 18 0/6 and 21 6/7 weeks, multiple gestations, or ultrasound performed for indication other than fetal anatomic assessment. Ultrasound reports were considered incomplete if they indicated suboptimal or non-visualization of any anatomic structures included in the comprehensive anatomic survey. Demographic data was compared using Student's t test and chi-square analysis where appropriate. Chi-square analysis was used to compare rates of completed surveys. p < .05 was considered significant.

RESULTS

After application of eligibility criteria, our cohort included 1,954 subjects. When comparing subjects with a completed scan to those with an incomplete scan, there were more white subjects in the incomplete group (p = .012), but other analyzed demographics were similar between groups. When using 18 weeks as a referent group, with each additional completed week of gestation, subjects were more likely to have a completed scan, at 19 weeks (OR 1.29, CI 1.05-1.58); at 20 weeks (OR 1.46, CI 1.1-1.95); at 21 weeks (OR 2.12, CI 1.42-3.17) (p < .05 for each). This association persisted when adjusting for demographic factors. To identify the optimal timing for the second trimester ultrasound for fetal evaluation, we re-analyzed the data using each completed week of gestational age as the referent group. When using 19 weeks as the referent group, the odds of a complete scan were lower at 18 weeks, and higher at 21 weeks, but not different at 20 weeks. When using 20 weeks as the referent group, the odds of a complete scan were lower at 18 weeks, but not different at 19 or 21 weeks. Finally, when using 21 weeks as the referent group, the odds of a complete scan were lower at 18 and 19 weeks, but not different at 20 weeks.

CONCLUSIONS

In this cohort of obese gravidas, the odds of having a completed anatomic survey continued to improve until 21 weeks gestational age. When comparing completed scans between each week, 18 weeks demonstrated consistently lower odds of a complete scan, however 20 weeks did not differ significantly from 19 weeks. Therefore, consideration should be made to perform the initial second trimester ultrasound for fetal evaluation in obese patients at 19 weeks gestational age to optimize completion rates while minimizing scans performed at advancing gestational ages.

Placental location and risk of retained placenta in women with a previous cesarean section: A population-based cohort study

INTRODUCTION

Some studies have shown that women with a previous cesarean section, compared with women with a previous vaginal delivery, have an increased risk of retained placenta during a subsequent vaginal delivery. It is unknown whether this is mediated by anterior placental location, when the placenta might cover the uterine scar. The aim of this study was to evaluate whether the increased risk of retained placenta in women with a previous cesarean section is mediated by anterior placental location.

MATERIAL AND METHODS

This is a population-based cohort study, with data from the regional population-based Stockholm-Gotland Obstetric Cohort, Sweden, from 2008 to 2014. The overall study population included 49 598 women with a vaginal second delivery, where adequate information about placental location from the second-trimester ultrasound scan was available. For the main analysis, including the 3921 women with a previous cesarean section, we calculated the relative risk of retained placenta in women with an anterior placental location, using women with non-anterior placental locations as reference. Relative risks were calculated as odds ratios (OR) with 95% CI. In a second model, adjustments were made for maternal age, height, country of birth, smoking in early pregnancy, infant sex, and in vitro fertilization.

RESULTS

In the overall study population, the rate of retained placenta at the second delivery was 2.0%. The proportion of women with a retained placenta was higher among women with a previous cesarean compared with those with a previous vaginal delivery (3.4% vs 1.9%; P < .0001). In the main analysis, including women with a previous cesarean section, the risk for retained placenta was not increased with anterior compared with non-anterior placental location (OR 0.84, 95% CI 0.60-1.20). Adjustments did not affect the estimates in a significant way.

CONCLUSIONS

The increased risk of retained placenta in women with a previous cesarean section is not mediated by anterior placental location.

Validation of Delphi procedure consensus criteria for defining fetal growth restriction

OBJECTIVE

Recently, a Delphi procedure was used to establish new criteria for defining fetal growth restriction (FGR). These criteria require clinical validation. We sought to validate the Delphi consensus criteria by comparing their performance with that of our current definition (estimated fetal weight (EFW) < 10^th percentile) in predicting adverse neonatal outcome (ANO).

METHODS

This was a secondary analysis of data from a prospective cohort study of women referred for fetal growth assessment between 26 and 36 weeks' gestation. The current standard definition of FGR used in our clinical practice is EFW < 10^th percentile using Hadlock's fetal growth standard. The Delphi consensus criteria for FGR include either a very small fetus (abdominal circumference (AC) or EFW < 3^rd percentile) or a small fetus (AC or EFW < 10^th percentile) with additional abnormal Doppler findings or a decrease in AC or EFW by two quartiles or more. The primary outcome was the prediction of a composite of ANO including one or more of: admission to the neonatal intensive care unit, cord pH < 7.1, 5-min Apgar score < 7, respiratory distress syndrome, intraventricular hemorrhage, neonatal seizures or neonatal death. The discriminatory capacities of the two definitions of FGR for composite ANO and delivery of a small-for-gestational-age (SGA) neonate, defined as birth weight < 10^th percentile, were compared using area under the receiver-operating-characteristics curve (AUC). The sensitivity, specificity and predictive values of the methods were also compared.

RESULTS

Of 1055 pregnancies included in the study, composite ANO occurred in 139 (13.2%). There were only two cases of early FGR (before 32 weeks); therefore, the study focused on late FGR. Our current FGR diagnostic criterion of EFW < 10^th percentile was not associated significantly with composite ANO (relative risk (RR), 1.1 (95% CI, 0.6-1.8)), while the Delphi FGR criteria were (RR, 2.0 (95% CI, 1.2-3.3)). Our current definition of FGR showed higher discriminatory ability in the prediction of a SGA neonate (AUC, 0.69 (95% CI, 0.65-0.73)) than did the Delphi definition (AUC, 0.64 (95% CI, 0.60-0.67)) (P = 0.001). The AUCs of both definitions were poor for the prediction of composite ANO, despite slightly improved performance using the Delphi consensus definition of FGR (AUC, 0.53 (95% CI, 0.50-0.55)) compared with that of our current definition (AUC, 0.50 (95% CI, 0.48-0.53)) (P = 0.02).

CONCLUSION

The newly postulated criteria for defining FGR based on a Delphi procedure detects fewer cases of neonatal SGA than does our current definition of EFW < 10^th percentile, but is associated with a slight improvement in predicting ANO. Copyright © 2020 ISUOG. Published by John Wiley & Sons Ltd.

The value of fetal growth biometry velocities to predict large for gestational age (LGA) infants

Objective: The use of growth velocities derived from fetal biometrics have been suggested to improve prediction of large for gestational age (LGA). Our objective was to determine if ultrasonographic growth velocities (GV) for abdominal circumference (AC) and estimated fetal weight (EFW) improve the prediction of LGA infants when compared to Hadlock EFW.Methods: This was a secondary analysis of data from a prospective study of women referred for growth ultrasounds during the 3rd trimester. Growth velocities (GV) for AC (AC - GV) and EFW (EFW - GV) were derived from the difference in Z-scores between measurements at the time of anatomy survey (18-24 week) and third trimester ultrasound (26-36 weeks). Change in AC - GV and EFW - GV >90th %ile alone or in combination with Hadlock EFW >90th%ile were compared for prediction of a LGA neonate. The primary outcome was the sensitivity and specificity of the (1) Hadlock EFW >90%ile, (2) AC - GV, (3) EFW - GV, (4) Hadlock EFW + AC - GV, and (5) Hadlock EFW + EFW - GV for the prediction of neonatal LGA. Test characteristics and area under the ROC curve (AUC) were determined. The association between the ultrasound predicted growth and adverse neonatal outcome was assessed using logistic regression.Results: Of 630 women meeting inclusion criteria, 85 (13.5%) had LGA neonates. Hadlock EFW showed a better NPV (98.0%) and sensitivity (71.1%) when compared to AC - GV (NPV 87.5%, sensitivity 17.7%) and EFW - GV (NPV 88.0%, sensitivity 22.6%). Combining Hadlock EFW and AC-GV or EFW - GV did little to improve the test characteristics for the prediction of LGA (AUC 0.65 and 0.64, respectively). All five measurements were unable to predict a composite of adverse neonatal outcome or need for maternal cesarean delivery. Adjustment of the growth velocities for gestational age at anatomy scan or 3rd trimester growth scan did not change these results.Conclusion: AC and EFW growth velocities do not appear to improve the prediction of LGA infants when compared to using the third trimester Hadlock EFW.

Utility of ultrasound assessment in management of pregnancies with preterm prelabor rupture of membranes

OBJECTIVES

To evaluate the utility of ultrasound markers in the management of pregnancies complicated by preterm prelabor rupture of membranes (PPROM) between 23 + 0 and 33 + 6 weeks' gestation, and to assess the ability of ultrasound markers to predict adverse neonatal outcomes.

METHODS

This was a retrospective cohort study of all patients with PPROM between 23 + 0 and 33 + 6 weeks' gestation and latency period (PPROM to delivery) > 48 h, who delivered before 34 weeks' gestation at a tertiary referral center between 2005 and 2017. All patients underwent a non-stress test daily and an ultrasound scan twice a week for assessment of amniotic fluid volume, biophysical profile (BPP) and umbilical artery (UA) pulsatility index (PI). In patients with suspected fetal growth restriction, fetal middle cerebral artery (MCA)-PI was also assessed and the cerebroplacental ratio (CPR) calculated. The last ultrasound examination performed prior to delivery was analyzed. We compared the characteristics and outcomes between women who were delivered owing to clinical suspicion of chorioamnionitis and those who were not delivered for this indication. The primary objective was to evaluate the utility of ultrasound in the management of patients with PPROM. The secondary objective was to assess the diagnostic performance of ultrasound markers (BPP score < 6, oligohydramnios, UA-PI > 95^th percentile, MCA-PI < 5^th percentile, CPR < 5^th percentile) for the prediction of composite adverse neonatal outcome, which was defined as the presence of one or more of: perinatal death, respiratory distress syndrome, periventricular leukomalacia, intraventricular hemorrhage Grade 3 or 4, necrotizing enterocolitis, hypoxic ischemic encephalopathy, neonatal sepsis or neonatal seizures.

RESULTS

A total of 504 women were included in the study, comprising 120 with suspected chorioamnionitis and 384 without. Women with suspected chorioamnionitis, compared with those without, were less likely to be nulliparous (34.2% vs 45.3%; P = 0.03) and more likely to have fever (50.8% vs 2.6%; P < 0.001) and be delivered by Cesarean section (69.2% vs 42.4%; P < 0.001), mainly owing to a history of previous Cesarean section (18.3% vs 9.1%; P = 0.005) and to having non-reassuring fetal heart rate tracings (32.5% vs 14.6%; P < 0.001). No significant differences were found between the two groups with regard to the median amniotic fluid volume, overall BPP score, BPP score < 6, MCA-PI or CPR. Median UA-PI was slightly higher in the suspected-chorioamnionitis group, yet the incidence of UA-PI > 95^th percentile was similar between the two groups. There was a higher incidence of composite adverse neonatal outcome in the group with suspected chorioamnionitis than in the group without (78.3% vs 64.3%, respectively; P = 0.004). However, on logistic regression analysis, none of the ultrasound markers evaluated was found to be associated with chorioamnionitis or composite adverse neonatal outcome, and they all had a poor diagnostic performance for the prediction of chorioamnionitis and composite adverse neonatal outcome.

CONCLUSIONS

Commonly used ultrasound markers in pregnancies complicated by PPROM were similar between women delivered for suspected chorioamnionitis and those delivered for other indications, and performed poorly in predicting composite adverse neonatal outcome. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Utility of follow-up standard sonography for fetal anomaly detection

BACKGROUND

In 2014, the Eunice Kennedy Shriver National Institute of Child Health and Human Development Fetal Imaging Workshop consensus recommended that sonograms be offered routinely to all pregnant women. In the absence of another indication, this examination is recommended at 18-22 weeks of gestation. Studies of anomaly detection often focus on pregnancies at risk for anomalies and on the yield of detailed sonography, topics less applicable to counseling low-risk pregnancies about the benefits and limitations of standard sonography. The clinical utility of follow-up sonogram in low-risk pregnancies for the purpose of fetal anomaly detection has not been established.

OBJECTIVE

The objective of the study was to evaluate the utility of follow-up standard sonography for anomaly detection among low-risk pregnancies in a nonreferred population.

STUDY DESIGN

We performed a retrospective cohort study of singleton pregnancies that underwent standard sonography at 18-21 6/7 weeks of gestation from October 2011 through March 2018 with subsequent delivery of a live-born infant at our hospital. Pregnancies with indications for detailed sonography in our system were excluded to evaluate fetal anomalies first identified with standard sonography. Anomalies were categorized according to the European Registration of Congenital Anomalies and Twins (EUROCAT) system, with confirmation based on neonatal evaluation. Among those with no anomaly detected initially, we evaluated the rate of subsequent detection according to number of follow-up sonograms, gestational age at sonography, organ system(s) affected, and anomaly severity. Statistical analyses were performed using χ² and a Mantel-Haenszel test.

RESULTS

Standard sonography was performed in 40,335 pregnancies at 18-21 6/7 weeks, and 11,770 (29%) had at least 1 follow-up sonogram, with a second follow-up sonogram in 3520 (9%). Major abnormalities were confirmed in 387 infants (1%), with 248 (64%) detected initially and 28 (7%) and 5 (1%) detected on the first and second follow-up sonograms. Detection of residual anomalies on follow-up sonograms was significantly lower than detection on the initial standard examination: 64% on initial examination, 45% for first follow-up, and 45% for second follow-up (P < .01). A larger number of follow-up examinations were required per anomalous fetus detected: 163 examinations per anomalous fetus detected initially, 420 per fetus detected at the first follow-up examination, and 705 per fetus detected at the second follow-up sonogram (P < .01). The number of follow-up examinations to detect each additional anomalous fetus was not affected by gestational age (P = .7). Survival to hospital discharge was significantly lower for fetuses with anomalies detected on initial (88%) than for fetuses with anomalies undetected until delivery (90 of 91, 99%; P < .002).

CONCLUSION

In a low-risk, nonreferred cohort with fetal anomaly prevalence of 1%, follow-up sonography resulted in detection of 45% of fetal anomalies that had not been identified during the initial standard sonogram. Significantly more follow-up sonograms were required to detect each additional anomalous fetus.

Risk factors for Cesarean delivery in pregnancy with small-for-gestational-age fetus undergoing induction of labor

OBJECTIVES

To identify risk factors for Cesarean delivery and non-reassuring fetal heart tracing (NRFHT) in pregnancies with a small-for-gestational-age (SGA) fetus undergoing induction of labor and to design and validate a prediction model, combining antenatal and intrapartum variables known at the time of labor induction, to identify pregnancies at increased risk of Cesarean delivery.

METHODS

This was a retrospective cohort study of non-anomalous, singleton gestations with a SGA fetus that underwent induction of labor, delivered in a single tertiary referral center between January 2011 and December 2016. SGA was defined as estimated fetal weight (EFW) < 10^th percentile. The primary outcome was to identify risk factors associated with Cesarean delivery. The secondary outcome was to identify risk factors associated with NRFHT. Univariate and multivariate analyses were used to determine which clinical characteristics, available at the time of admission, had the strongest association with Cesarean delivery and NRFHT during labor induction. The predictive value of the final models was assessed by the area under the receiver-operating-characteristics curve (AUC). Sensitivity and specificity of the models were also assessed. Internal validation of the models was performed using 10 000 bootstrap replicates of the original cohort. The adequacy of the models was evaluated using the Hosmer-Lemeshow goodness-of-fit test.

RESULTS

A total of 594 pregnancies were included. Cesarean delivery was performed in 243 (40.9%) pregnancies. Significant risk factors associated with Cesarean delivery, and included in the final model, were maternal age, gestational age at delivery and initial method of labor induction. The bootstrap estimate of the AUC of the final prediction model for Cesarean delivery was 0.82 (95% CI, 0.78-0.86). The model had sensitivity of 64.2%, specificity of 86.9%, positive likelihood ratio (LR) of 4.9 and negative LR of 0.41. The model had good fit (P = 0.617). NRFHT complicated 117 (19.7%) pregnancies. Significant risk factors for NRFHT included EFW < 5^th percentile, abnormal umbilical artery Doppler studies (pulsatility index > 95^th percentile or absent/reversed end-diastolic flow) and gestational age at delivery. The final prediction model for NRFHT had an AUC of 0.69 (95% CI, 0.63-0.75) and specificity of 97.0%.

CONCLUSION

We identified several significant risk factors for Cesarean delivery and NRFHT among SGA pregnancies undergoing induction of labor. Clinicians may use these risk factors to guide patient counseling and to help anticipate the potential need for operative delivery. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Detailed Fetal Anatomic Ultrasound Examination Duration and Association With Body Mass Index

OBJECTIVE

To evaluate the association of the duration of the detailed fetal anatomic ultrasound examination with maternal body mass.

METHODS

This was a retrospective chart review of patients presenting to our clinic for detailed fetal anatomic examinations between January 1, 2010, and June 30, 2017. After excluding multifetal pregnancies and other examinations expected to have a longer duration, a total of 6,522 examinations were performed between 18 0/7 and 22 0/7 weeks of gestation. Results were analyzed using analysis of variance and Student's t-test.

RESULTS

Mean (SD) body mass index (BMI) was 29.3 (±7.7), and mean examination time was 51.5 (±10.4) minutes. We found that mean examination time was 48.8 (±9.6) minutes for patients with normal BMIs, 50.6 (±10.0) minutes for overweight patients, 52.2 (±10.4) minutes for patients with class I obesity, 54.6 (±10.3) minutes for patients with class II obesity, and 57.7 (±10.3) minutes for patients with class III obesity (P<.001). The duration of the detailed fetal anatomic ultrasound examination increased continuously with BMI (r=0.285, P<.001).

CONCLUSION

We found that the duration of detailed fetal anatomic examinations increased with BMI. Examinations for gravid patients with class III obesity lasted 8.9 minutes longer than those for gravid patients with normal BMIs; examinations for gravid patients with BMIs of 50 or higher lasted 13.5 minutes longer. This information may be useful for fetal ultrasound examination scheduling.

Development of placental abnormalities in location and anatomy

Low‐lying placentas, placenta previa and abnormally invasive placentas are the most frequently occurring placental abnormalities in location and anatomy. These conditions can have serious consequences for mother and fetus mainly due to excessive blood loss before, during or after delivery. The incidence of such abnormalities is increasing, but treatment options and preventive strategies are limited. Therefore, it is crucial to understand the etiology of placental abnormalities in location and anatomy. Placental formation already starts at implantation and therefore disorders during implantation may cause these abnormalities. Understanding of the normal placental structure and development is essential to comprehend the etiology of placental abnormalities in location and anatomy, to diagnose the affected women and to guide future research for treatment and preventive strategies. We reviewed the literature on the structure and development of the normal placenta and the placental development resulting in low‐lying placentas, placenta previa and abnormally invasive placentas.