Using ultrasound in the clinical management of placental implantation abnormalities

Vasa Previa and the Role of Fetal Fibronectin and Cervical Length Surveillance: A Review

Vasa previa is a pregnancy complication that occurs when unprotected fetal blood vessels traverse the cervical os, placing the fetus at high risk of exsanguination and fetal death. These fetal vessels may be compromised by fetal movement and compression, leading to poor oxygen distribution and asphyxiation. Diagnostic tools for vasa previa management and preterm labor (PTL) include transvaginal ultrasound, cervical length (CL) surveillance and use of fetal fibronectin (FFN) testing. These tools can prove to be quite useful as they allow for lead time in the prediction of PTL and spontaneous rupture of membranes which can result in devastating outcomes for pregnancies affected by vasa previa. We conducted a literature review on vasa previa management and the usefulness of FFN and CL surveillance in predicting PTL and found 36 related papers. Although there is limited research available to show the impact of FFN and CL surveillance in the management of vasa previa, there is sufficient evidence to support FFN and CL surveillance in predicting the onset of PTL, which can have devastating consequences for the pregnancies affected. It can be extrapolated that these tools, by helping to determine pregnancies at risk for PTL, could improve management and outcomes in patients with vasa previa. Future studies investigating the management of vasa previa with FFN and CL surveillance to reduce the burden of PTL and its associated comorbidities are warranted.

CT angiography for characterization of advanced placenta accreta spectrum: indications, risks, and benefits

Placenta accreta spectrum disorder (PASD) encompasses various types of abnormal placentation in which chorionic villi directly adhere to or invade the myometrium. The incidence of PASD has dramatically risen in the US over the past 3 decades owing to the increased rates of patients undergoing cesarean sections. While PASD remains a significant cause of maternal morbidity and mortality, accurate prenatal identification and characterization of PASD is associated with improved outcomes. Although ultrasound is the first-line imaging modality in the evaluation of PASD, with MRI serving as an adjunct, computed tomography angiography (CTA) may also offer unique diagnostic advantages in cases of advanced PASD by providing superior visualization of placental and abdominopelvic vasculature and enabling the creation of comprehensive vascular maps to roadmap complex surgical interventions. This paper represents the first evaluation of CTA as a diagnostic tool and operative planning aid in this context. Appropriate indications and diagnostic advantages of CTA in this setting are reviewed, and key multimodal imaging features of normal and abnormal placentation are highlighted.

Association between short inter-pregnancy interval and placenta previa and placenta accreta spectrum with respect to maternal age at first cesarean delivery

OBJECTIVE

To explore the association between inter-pregnancy intervals and placenta previa and placenta accreta spectrum among women who had prior cesarean deliveries with respect to maternal age at first cesarean delivery.

METHODS

This retrospective study included clinical data from 9981 singleton pregnant women with a history of cesarean delivery at 11 public tertiary hospitals in seven provinces of China between January 2017 and December 2017. The study population was divided into four groups (<2, 2-5, 5-10, ≥10 years of the interval) according to the inter-pregnancy interval. The rate of placenta previa and placenta accreta spectrum among the four groups was compared, and multivariate logistic regression was used to analyze the relationship between inter-pregnancy interval and placenta previa and placenta accreta spectrum with respect to maternal age at first cesarean delivery.

RESULTS

Compared to women aged 30-34 years old at first cesarean delivery, the risk of placenta previa (aRR, 1.48; 95% CI, 1.16-1.88) and placenta accreta spectrum (aRR, 1.74; 95% CI, 1.28-2.35) were higher among women aged 18-24. Multivariate regression results showed that women at 18-24 with <2 years intervals exhibited a 5.05-fold increased risk for placenta previa compared with those with 2-5-year intervals (aRR, 5.05; 95% CI, 1.13-22.51). In addition, women aged 18-24 with less than 2 years intervals had an 8.44 times greater risk of developing PAS than women aged 30-34 with 2 to 5 years intervals (aRR, 8.44; 95% CI, 1.82-39.26).

CONCLUSIONS

The findings of this study suggested that short inter-pregnancy intervals were associated with increased risks for placenta previa, and placenta accreta spectrum for women under 25 years at first cesarean delivery, which may be partly attributed to obstetrical outcomes.

Factors associated with low birthweight among late preterm singletons in Japan using pregnancy birth registry data

Late preterm (LP, born between 34 0/7 and 36 6/7 weeks of gestation) infants may experience several adverse outcomes, similar to those experienced by low birthweight (LBW, birthweight <2500 g) infants. However, while LP infants are often born with LBW, the association between LP and LBW remains unknown. This study aimed to investigate LBW rate and independent risk factors for LBW in LP singleton neonates. We retrospectively analyzed data of LP singleton neonates, born between 2013 and 2017, from the Japan Society of Obstetrics and Gynecology Successive Pregnancy Birth Registry System. The exclusion criteria included stillbirths and infants with missing data. Logistic regression analyses were performed to investigate maternal and perinatal factors associated with LBW in LP singletons. LBW was observed in 62.5% (n = 35,113) of 56,160 LP singleton births. In the multiple logistic regression analysis, LBW in LP neonates was independently associated with modifiable maternal factors, including pre-pregnancy underweight, inadequate gestational weight gain, and smoking during pregnancy, as well as non-modifiable factors, including younger maternal age, nulliparity, hypertensive disorder of pregnancy, preeclampsia, cesarean section delivery, and female offspring. According to the Japanese pregnancy birth registry data, more than half of LP neonates were LBW. We previously discussed the issue of LBW regarding infants with different backgrounds, as there are many different causes of LBW. Several risk factors should be subdivided and considered for the risk of LP and LBW.

Perinatal Mortality Despite Prenatal Diagnosis of Vasa Previa: A Systematic Review

OBJECTIVE

To determine the causes and potential preventability of perinatal deaths in prenatally identified cases of vasa previa.

DATA SOURCES

Reports of prenatally identified cases of vasa previa published in the English language literature since 2000 were identified in Medline and ClinicalTrials.gov with the search terms "vasa previa," "abnormal cord insertion," "velamentous cord," "marginal cord," "bilobed placenta," and "succenturiate lobe."

METHODS OF STUDY SELECTION

All cases from the above search with an antenatally diagnosed vasa previa present at delivery in singleton or twin gestations with perinatal mortality information were included.

TABULATION, INTEGRATION, AND RESULTS

Cases meeting inclusion criteria were manually abstracted, and multiple antenatal, intrapartum, and outcome variables were recorded. Deaths and cases requiring neonatal transfusion were analyzed in relation to plurality, routine hospitalization, and cervical length monitoring. A total of 1,109 prenatally diagnosed cases (1,000 singletons, 109 twins) were identified with a perinatal mortality rate attributable to vasa previa of 1.1% (95% CI 0.6-1.9%). All perinatal deaths occurred with unscheduled deliveries. The perinatal mortality rate in twin pregnancies was markedly higher than that in singleton pregnancies (9.2% vs 0.2%, P <.001), accounting for 80% of overall mortality despite encompassing only 9.8% of births. Compared with individuals with singleton pregnancies, those with twin pregnancies are more likely to undergo unscheduled delivery (56.4% vs 35.1%, P =.01) despite delivering 2 weeks earlier (33.2 weeks vs 35.1 weeks, P =.006). An institutional policy of routine hospitalization is associated with a reduced need for neonatal transfusion (0.9% vs 6.0%, P <.001) and a reduction in the perinatal mortality rate in twin pregnancies (0% vs 25%, P =.002) but not in singleton pregnancies (0% vs 0.5%, P =.31).

CONCLUSION

Routine hospitalization and earlier delivery of twins may result in a reduction in the perinatal mortality rate. A smaller benefit from routine admission of individuals with singleton pregnancies cannot be excluded. There is currently insufficient evidence to recommend the routine use of cervical length measurements to guide clinical management.

Current practice of placental cord insertion documentation in Australia - A sonographer survey

Introduction

During pregnancy, the umbilical cord attaches to the placenta in a central, eccentric, marginal or velamentous location. Maternal and fetal complications are associated with marginal and velamentous cord insertions, the most clinically significant being perinatal mortality due to undiagnosed vasa praevia. Current literature describes a wide variation regarding regulation of placental cord insertion (PCI) documentation during antenatal ultrasound examinations. This prospective cross-sectional study aimed to assess the current practice of antenatal PCI documentation in Australia.

Methods

Members of the Australian Sonographer Accreditation Registry were invited to participate in an online survey which was distributed between February and March 2022.

Results

Four hundred ninety sonographers met the inclusion criteria for the study of which 330 (67.3%) have more than 10 years' experience as a sonographer and 375 (76.5%) are employed primarily in a public or private setting offering general ultrasound. Most respondents (89.6%) indicated documentation of the PCI site is departmental protocol at the second trimester anatomy scan (17-22 weeks gestation), but PCI documentation is protocol in less than 50% of other obstetric ultrasound examinations listed in the survey. The PCI site is included in the formal ultrasound report at a rate significantly less than inclusion in the departmental protocol and the sonographer's worksheet.

Conclusions

Considering the potential maternal and fetal complications associated with abnormal PCI and the ease at which the PCI site is identified in the first and second trimesters, we believe that standard inclusion of the PCI site in departmental protocol and in the formal ultrasound report from 11 weeks gestation, regardless of whether it is normal or abnormal, would prove invaluable.

In vitro Fertilization: An Alert for the Association of Placenta Previa and Vasa Previa - Ultrasound and Magnetic Resonance Imaging Findings

A 33-year-old woman, gravida 2 para 0, with a history of two previous miscarriages, underwent an investigation for recurrent miscarriage. After genetic counseling, the couple were submitted to the karyotype, which resulted in 45, X/46, XX mosaicism (mosaic Turner syndrome) in the wife result, while the husband chromosomal resulted in 46, XY (normal). After evaluating the options, the couple opted for in vitro fertilization. During prenatal follow-up, placenta and vasa previa were identified, considerably increasing the maternal-fetal mortality rate in this case. However, despite being a delicate and challenging case, the early diagnose was possible due to transvaginal ultrasound using color Doppler. Due to good care in obstetric follow-up, involving a multidisciplinary team, a therapeutic program and a successful outcome were possible. The patient underwent a cesarean section at 35 weeks of pregnancy, without complications, with a newborn in good general condition, despite the prematurity.

Efficacy of distal haemostasis during caesarean delivery in women with placenta accreta spectrum disorders

Pregnancies complicated by the placenta praevia are associated with an increased risk of massive obstetric bleeding and high rates of hysterectomy which are often caused by the placenta accreta. The aim of our study was to identify the risk factors for placenta praevia associated with PAS disorders and the efficacy of distal haemostasis during Cesarean delivery.

METHODS

This was a cohort study carried out between 2014 and 2020 in 532 women with abnormal placental localization and attachment. The placental attachment spectrum (PAS) disorder diagnosis was confirmed during the surgery and by the histology results in 164/532 participants. Depending on the surgical approach during the Cesarean delivery, patients were divided into three groups. In Group 1 (n = 52), patients underwent bilateral uterine artery ligation. In Group 2 (n = 33), we used the combined compression haemostasis approach including the placement of tourniquets and insertion of an intrauterine balloon for controlled tamponade. In Group 3 (n = 79), we used the combination of surgical haemostasis with the controlled intrauterine tamponade using the vaginal and intrauterine Zhukovsky balloon.

RESULTS

PAS was observed in 30.8% of the placenta praevia cases, and in 93.3% was associated with the presence of a uterine scar. Women with the placenta praevia and PAS had a significantly higher number of past deliveries (р = .001). According to the FIGO classification, 53.8% of women with placenta praevia observed during the Cesarean had РА1 and 46.2% PA2. With regards to the PAS disorders observed in 30.8% of patients, 38.4% had PAS3, 34.7% PAS4, 18.3% PAS5 and 8.5% PAS6. The histology analysis showed normal placental attachment in 42.9% of the total number of study participants, placenta accreta in 28.2%, placenta increta in 16.7%, and placenta percreta in 12.2%. In Group 1, we performed the resection of uterine wall with the attached portion of the placenta in 13.5% of women, in Group 2 in 30.3% women, and in Group 3 in 50.6% women. There was a significant 4.8-fold reduction in the number of hysterectomies in Group 3 versus Group 2 (р = .043) and a 4.4-fold reduction in Group 2 versus Group 1 (р = .003). In Group 2, the volume of blood loss was 1.3-fold lower and in Group 3 1.5-fold lower than in Group 1. Conclusion: The techniques of compression distal haemostasis evaluated in this study in women with PAS are efficacious in the reduction of adverse maternal outcomes and should be used more widely in clinical practice.

Longitudinal Proteomic Analysis of Plasma across Healthy Pregnancies Reveals Indicators of Gestational Age

Longitudinal changes in the blood proteome during gestation relate to fetal development and maternal homeostasis. Charting the maternal blood proteome in normal pregnancies is critical for establishing a baseline reference when assessing complications and disease. Using mass spectrometry-based shotgun proteomics, we surveyed the maternal plasma proteome across uncomplicated pregnancies. Results indicate a significant rise in proteins that govern placentation and are vital to the development and health of the fetus. Importantly, we uncovered proteome signatures that strongly correlated with gestational age. Fold increases and correlations between the plasma concentrations of ADAM12 (ρ = 0.973), PSG1 (ρ = 0.936), and/or CSH1/2 (ρ = 0.928) with gestational age were validated with ELISA. Proteomic and validation analyses demonstrate that the maternal plasma concentration of ADAM12, either independently or in combination with either PSG1 or CSH1/2, correlates with gestational age within ±8 days throughout pregnancy. These findings suggest that the gestational age in healthy pregnancies may be determined by referencing the concentration of select plasma proteins.

What fetal medicine specialists should know about the monochorionic placenta

Monochorionic twins are at risk of transfusion imbalances as long as they are connected to the shared placenta during their intrauterine journey. This review article addresses the macroscopic examination of the monochorionic placenta at the time of birth and explains placental dye injection studies to document the vascular anastomoses and placental sharing. We elaborate on the different types of anastomoses, the importance of how the placenta is divided between the twins, and the angioarchitecture in twin-twin transfusion syndrome, twin anemia polycythemia sequence and selective fetal growth restriction.

Timing of birth and adverse pregnancy outcomes in cases of prenatally diagnosed vasa previa: a systematic review and meta-analysis

OBJECTIVE

The ideal time for birth in pregnancies diagnosed with vasa previa remains unclear. We conducted a systematic review aiming to identify the gestational age at delivery that best balances the risks for prematurity with that of pregnancy prolongation in cases with prenatally diagnosed vasa previa.

DATA SOURCES

Ovid MEDLINE, PubMed, CINAHL, Embase, Scopus, and Web of Science were searched from inception to January 2022.

STUDY ELIGIBILITY CRITERIA

The intervention analyzed was delivery at various gestational ages in pregnancies prenatally diagnosed with vasa previa. Cohort studies, case series, and case reports were included in the qualitative synthesis. When summary figures could not be obtained directly from the studies for the quantitative synthesis, authors were contacted and asked to provide a breakdown of perinatal outcomes by gestational age at birth.

METHODS

Study appraisal was completed using the National Institutes of Health quality assessment tool for the respective study types. Statistical analysis was performed using a random-effects meta-analysis of proportions.

RESULTS

The search identified 3435 studies of which 1264 were duplicates. After screening 2171 titles and abstracts, 140 studies proceeded to the full-text screen. A total of 37 studies were included for analysis, 14 of which were included in a quantitative synthesis. Among 490 neonates, there were 2 perinatal deaths (0.4%), both of which were neonatal deaths before 32 weeks' gestation. In general, the rate of neonatal complications decreased steadily from <32 weeks' gestation (4.6% rate of perinatal death, 91.2% respiratory distress, 11.4% 5-minute Apgar score <7, 23.3% neonatal blood transfusion, 100% neonatal intensive care unit admission, and 100% low birthweight) to 36 weeks' gestation (0% perinatal death, 5.3% respiratory distress, 0% 5-minute Apgar score <7, 2.9% neonatal blood transfusion, 29.2% neonatal intensive care unit admission, and 30.9% low birthweight). Complications then increased slightly at 37 weeks' gestation before decreasing again at 38 weeks' gestation.

CONCLUSION

Prolonging pregnancies until 36 weeks' gestation seems to be safe and beneficial in otherwise uncomplicated pregnancies with antenatally diagnosed vasa previa.

Pregnancy and Delivery Outcomes in Women With Persistent Versus Resolved Low-Lying Placenta in the Late Third Trimester

OBJECTIVES

The safest mode of delivery in low-lying placenta is debatable. Little is known about outcomes in low-lying placenta resolved during the late third trimester. We compare outcomes of women with persistent versus resolved low-lying placenta.

METHODS

A retrospective analysis on a prospective cohort of women with low-lying placenta confirmed at 28-30 weeks sonography (01/2009 to 03/2018). Women were followed up serially every 2 to 3 weeks until delivery to assess the placental edge-to-internal os distance (IOD), and included if scan was performed within 28 days before delivery.

RESULTS

There were 86 women: in 21 the low-lying placenta resolved, whereas in 65 persisted (n = 15 IOD 1-10 mm, n = 50 IOD 11-20 mm). Antepartum bleeding associated with higher rates of urgent cesarean delivery in 1-10 mm (P = .041) but not in 11-20 mm (P = 1.000) and >20 mm (P = .333). Among women with IOD >10 mm allowed to labor, vaginal delivery occurred in 76.7% (11-20 mm) and 94.1% (>20 mm) (P = .155), with no difference according to parity (70% and 80% in multiparas, P = .696; 60% and 72.7% in nulliparas, P = .698). Severe PPH (P = .922) and hemoglobin drop (P = .109) were similar among groups. Women with IOD 11-20 mm and >20 mm and vaginal delivery bled less than women with similarly located placenta and cesarean delivery (P = .009 and P = .048).

CONCLUSIONS

Women with IOD >10 mm have high chances of deliver vaginally with no further increase of their hemorrhagic risk. Success of vaginal delivery is independent of parity and antepartum bleeding. Labor should be managed in an adequate hospital setting.

Clinical characteristics of a novel "Type 3" vasa previa: case series at a single center

OBJECTIVE

Vasa previa is a condition in which fetal blood vessels are located on fetal membranes within 2 cm of the internal cervical os. Vasa previa has been classified into two types: Type 1, in which vessels connect a velamentous umbilical cord to the placenta, and Type 2, in which vessels connect the lobes of a bilobed placenta or the placenta to a succenturiate lobe. However, there are also atypical cases that cannot be classified into these two types. These cases are manifested by a center or marginal cord insertion with a normal shaped placenta, and fetal vessels were also located on membranes around the internal cervical os. These cases were recently proposed as Type 3 vasa previa. The present study investigated the incidence of Type 3 vasa previa and elucidated differences in clinical and ultrasonographical characteristics between traditional types and Type 3.

METHODS

This was a single-center observational study using a cohort of all vasa previa cases between January 2010 and April 2020.

RESULTS

Among 8,723 deliveries, there were 14 cases (0.16%) of vasa previa, all of which were diagnosed prenatally by US, not after vaginal delivery or CS. There were 9 (64%), 0, and 5 (36%) cases of Types 1, 2, and 3, respectively. All 5 Type 3 cases had only one fetal aberrant vessel of vasa previa, while 6 out of 9 Type 1 cases (67%) had two or more aberrant vessels. Seven Type 1 cases (78%) possessed two or more known risk factors, such as velamentous cord insertion, whereas all Type 3 cases only had one. Difficulties were associated with diagnosing two out of the 14 cases of vasa previa using routine transvaginal ultrasonography (TVUS). In these cases, the aberrant fetal vessel of vasa previa was only one vein with a thin wall that was not clearly visualized by gray-scale TVUS as well as slow flow that was easily misread by color-Doppler. These cases were ultimately diagnosed as vasa previa based on non-pulsatile flow detected by color and pulsed Doppler.

CONCLUSIONS

The present results suggest that Type 3 may account for a large proportion of vasa previa cases. Most Type 3 cases may present with only one fetal aberrant vessel of vasa previa and fewer risk factors, suggesting that the diagnosis of vasa previa may be more challenging in Type 3 cases than in the other types. Vasa previa with a venous vasa previa needs to be considered because of the difficulties associated with an antenatal diagnosis due to unclear imaging of the vasculature or the lack of specific color Doppler flow patterns. Pulsed Doppler imaging may be helpful for the diagnosis of these cases.

Guideline No. 402: Diagnosis and Management of Placenta Previa

OBJECTIVES

To summarize the current evidence and to make recommendations for diagnosis and classification of placenta previa and for managing the care of women with this diagnosis.

OPTIONS

To manage in hospital or as an outpatient and to perform a cesarean delivery preterm or at term or to allow a trial of labour when a diagnosis of placenta previa or a low-lying placenta is suspected or confirmed.

OUTCOMES

Prolonged hospitalization, preterm birth, rate of cesarean delivery, maternal morbidity and mortality, and postnatal morbidity and mortality.

INTENDED USERS

Family physicians, obstetricians, midwives, and other maternal care providers.

TARGET POPULATION

Pregnant women with placenta previa or low-lying placenta.

EVIDENCE

Medline, PubMed, Embase, and the Cochrane Library were searched from inception to October 2018. Medical Subject Heading (MeSH) terms and key words related to pregnancy, placenta previa, low-lying placenta, antepartum hemorrhage, short cervical length, preterm labour, and cesarean. This document represents an abstraction of the evidence rather than a methodological review.

VALIDATION METHODS

This guideline has been reviewed by the Maternal-Fetal Medicine and Diagnostic Imaging committees of the Society of Obstetricians and Gynaecologists of Canada (SOGC) and approved by the SOGC Board of Directors.

BENEFITS, HARMS, AND/OR COSTS

Women with placenta previa or low-lying placenta are at increased risk of maternal, fetal and postnatal adverse outcomes that include a potentially incorrect diagnosis and possibly unnecessary hospitalization, restriction of activities, early delivery, or cesarean delivery. Optimization of diagnosis and management protocols has potential to improve maternal, fetal and postnatal outcomes.

SUMMARY STATEMENTS (GRADE RATINGS IN PARENTHESES)

RECOMMENDATIONS (GRADE RATINGS IN PARENTHESES).

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.

ACR Appropriateness Criteria® Placenta Accreta Spectrum Disorder

Placenta accreta spectrum disorder (PASD) is the current terminology recommended by the International Federation of Obstetrics and Gynecology (FIGO) and should replace terms such as abnormally adherent/invasive placenta or morbidly adherent placenta. PASD refers to a variety of potential clinical complications, which may result from abnormal placental implantation. More specifically, placenta accreta refers to a defect in the decidua basalis where the chorionic villi adhere directly to the myometrium with trophoblastic invasion. Accurate antenatal diagnosis is needed to plan for an appropriate delivery strategy at an experienced center in order to reduce maternal and potential fetal morbidity and mortality. Obtaining radiologic and clinical data when PASD is first suspected can play a significant role in formulating an appropriate delivery strategy. Depending on the clinical risk factors and initial imaging findings, transabdominal ultrasound of the pregnant uterus with duplex Doppler and transvaginal ultrasound as needed are the most appropriate imaging procedures. 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.

Unique Case of a Tenth Cesarean Section in an Emirati Woman

Cesarean deliveries have risen significantly over the past few decades due to advanced maternal age, defensive obstetric practice, medico-legal concerns, and maternal request. A cesarean section is a life-saving surgical procedure when certain complications arise during pregnancy and labor. However, it is a major surgery and is associated with immediate maternal and perinatal risks and may have implications for future pregnancies as well as long-term effects that are still being investigated. A major obstetric hazard of repeat cesarean section is the increased risk of uterine scar rupture during pregnancy resulting in high fetal and maternal morbidity and mortality. Also, there are increased risks associated with placenta previa and placenta accreta spectrum. We present a unique case of a woman who underwent her 10th cesarean section which was uncomplicated.

Case report: a rapid review approach used by the UK National Screening Committee to inform recommendations on general population screening for vasa praevia

BACKGROUND

The UK National Screening Committee (UK NSC) reviews evidence about existing or potential population screening programmes using rapid review products called evidence summaries. We provide a case report as an example of how rapid reviews are developed within the UK NSC's process, consider how the quality of rapid reviews should be assessed and ask whether the rapid review was an appropriate tool to inform the UK NSC's decision-making process.

METHODS

We present the rapid review approach taken by the commissioner and the reviewers to develop an evidence summary for vasa praevia (VP), which the UK NSC reappraised as part of its 3-yearly cycle for conditions where screening is currently not recommended. We apply the AMSTAR 2 quality appraisal checklist for systematic reviews, the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist and a published checklist of items to consider with a rapid review approach. As UK NSC evidence summaries do not include meta-analyses, any related AMSTAR 2 or PRISMA checklist items were considered inapplicable.

RESULTS

The evidence summary was available within the required timelines and highlighted little change from the previous review in terms of key evidence gaps relating to the epidemiology of VP, the screening test and the management pathway. Therefore, the UK NSC concluded that there was insufficient evidence to support a change in its previous recommendation against screening. The evidence summary scored moderately against the applicable AMSTAR 2 and PRISMA checklist items. Against the published checklist of items to consider with a rapid review approach, the evidence summary performed well.

CONCLUSIONS

In this case report, the use of a rapid review as part of the UK NSC's process enabled a pragmatic approach to assessing the overall volume, quality and direction of literature on key questions relating to the viability of a population screening programme for VP. Based on our assessments of this single evidence summary, systematic review quality appraisal tools may undervalue rapid reviews. The validity of the methods used in this case report, as well as the wider generalisability of our insights relating to rapid review practice, reporting and quality assessment, requires analysis of a larger sample of rapid reviews.

Risk scoring system with MRI for intraoperative massive hemorrhage in placenta previa and accreta

BACKGROUND

Placenta previa and accreta are serious obstetric conditions that are associated with a high risk of intraoperative massive hemorrhage.

PURPOSE

To develop a scoring system for intraoperative massive hemorrhage combining MRI and clinical characteristics to predict the risk of massive hemorrhage in placenta previa and accreta STUDY TYPE: Retrospective cohort study.

SUBJECTS

In all, 374 patients consisting of 259 patients with placenta previa and accreta after previous cesarean section (CS) for the derivation cohort and 115 patients for the validation cohort.

FIELD STRENGTH/SEQUENCE

1.5T single-shot fast spin-echo sequence. [Correction added on October 23, 2019, after first online publication: The field strength in the preceding sentence was corrected.] ASSESSMENT: Using the derivation cohort, clinical and MRI data were collected and multivariable logistic regressions analysis was conducted to develop a scoring system for prediction of intraoperative massive bleeding (blood loss volume > 2000 mL). Finally, the scoring system was validated on 115 patients.

STATISTICAL TESTS

Student's t-test, Mann-Whitney U-test, X ² statistics, multivariable analysis, and receiver operating characteristic (ROC) analysis.

RESULTS

Ten indicators, including clinically maternal age (1 point), preoperative hemoglobin level (1 point), gravidity number (1 point), number of CS (1 point), and MRI T₂ dark intraplacental bands (4 points), cervical canal length (3 points), placenta thickness on the uterine scar area (4 points), empty vascular shadow of the uterus (1 point), low signal discontinuity in the muscular layer of the posterior wall of the bladder (6 points) and attachment position of the placenta (1 point) were imputed. From the ROC analysis, a total score of 7 points was identified as the optimal cutoff value, allowing good differentiation of intraoperative massive bleeding in the derivation cohort (AUC, 0.863; 95% confidence interval [CI]: 0.811-0.916) and in the validation cohort (AUC, 0.933; 95% CI: 0.885-0.980).

DATA CONCLUSION

The scoring system for intraoperative massive hemorrhage consists of MRI and clinical indicators, and using a cutoff value of 7 points for a high risk of massive bleeding, the developed scoring system could accurately assess the risk of intraoperative massive hemorrhage in patients with placenta previa and accreta. This scoring system can potentially reduce the incidence of intraoperative massive bleeding by identifying patients at high risk.

LEVEL OF EVIDENCE

3 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2020;51:947-958.

Vasa previa: prenatal diagnosis and management

PURPOSE OF REVIEW

Vasa previa is a rare disorder of placentation associated with a high rate of perinatal morbidity and mortality when undetected before delivery. We have evaluated the recent evidence for prenatal diagnosis and management of vasa previa.

RECENT FINDINGS

Around 85% of cases of vasa previa have one or more identifiable risk factors including in-vitro fertilization, multiple gestations, bilobed, succenturiate or low-lying placentas, and velamentous cord insertion. The development of standardized prenatal targeted scanning protocols may improve perinatal outcomes. There is no clear consensus on the optimal surveillance strategy including the need for hospitalization, timing of corticosteroids administration and the value of transvaginal cervical length measurements. Outpatient management is possible if there is no evidence of cervical shortening on ultrasound and there are no symptoms of bleeding or uterine contractions. Recent national guidelines and expert reviews have recommended scheduled cesarean section of all asymptomatic women presenting with vasa previa between 34 and 36 weeks' gestation.

SUMMARY

Prenatal diagnosis of vasa previa is pivotal to prevent intrapartum fetal death. Although there is insufficient evidence to support the universal mid-gestation ultrasound screening for vasa previa, recent evidence indicates the need for standardized prenatal targeted screening protocols of pregnancies at high-risk of vasa previa.

Is scanning for vasa previa important for singleton pregnancies that started as multiple conceptions?

OBJECTIVES

Vasa previa (VP) is a congenital placentation disorder in which fetal vessels run across the internal os of the cervix under the fetal presentation. This rare condition is associated with a high rate of perinatal morbidity and mortality when undetected before delivery. Roughly 85% of all cases of VP can be associated with one or more identifiable risk factors including in-vitro fertilization (IVF), multiple gestations, bilobed, succenturiate or low-lying placentas, and velamentous cord insertion (VCI). Recent evidence indicates the need for standardized prenatal targeted scanning protocols of pregnancies at risk of VP. The present study reports on pregnancies that began with multiple gestations but ended with a single fetus diagnosed with VP.

STUDY DESIGN

We retrospectively collected and reviewed medical records from 2006 to 2018 of early multiple pregnancies that ended with a single fetus diagnosed with VP in our medical center, including three cases of twin gestation complicated by a vanishing twin and a case of multifetal reduction in triplet pregnancy. This retrospective cohort study was approved by our Institutional Clinical Research Committee.

RESULTS

The database search identified 50 pregnancies that started as multiple gestations but continued as singletons. Of these, 4 pregnancies were diagnosed with VP, for a prevalence of 8.0%. For two of the four cases, the diagnosis was made during delivery as expressed by a low Apgar score at 1 and 5 min, a low cord blood pH value, newborn resuscitation, blood product transfusion, and NICU supervision. There was a statistically significant difference in the prevalence of VP in pregnancies that started as multiple gestations but continued later as singletons compared to multiple pregnancies (8.0% vs. 0.2% respectively, p < 0.0001). The OR for VP in pregnancies that started as multiple gestations but continued as singletons was 41.1 (95% CI, 12.77-131.94).

CONCLUSIONS

Our findings suggest there is an increased risk of VP in conceptions that started as viable multiple gestations but continued later as singletons. If our findings supported by others, it may be prudent to consider all twins at the beginning of pregnancy to be at risk for VP, irrespective of the actual number of life fetuses at later stages of gestation.

Prenatal planning of placenta previa: diagnostic accuracy of a novel MRI-based prediction model for placenta accreta spectrum (PAS) and clinical outcome

PURPOSE

To investigate the diagnostic accuracy of MRI for placenta accreta spectrum (PAS) and clinical outcome prediction in women with placenta previa, using a novel MRI-based predictive model.

METHODS

Thirty-eight placental MRI exams performed on a 1.5T scanner were retrospectively reviewed by two radiologists in consensus. The presence of T2 dark bands, myometrial thinning, abnormal vascularity, uterine bulging, placental heterogeneity, placental protrusion sign, placental recess, and percretism signs was scored using a 5-point scale. Pathology and clinical intrapartum findings were the standard of reference for PAS, while intrapartum/peripartum bleeding and emergency hysterectomy defined the clinical outcome. Receiver-operating characteristic (ROC) analysis and discriminant function analysis were performed to test the predictive power of MRI findings for both PAS and clinical outcome prediction.

RESULTS

Abnormal vascularity and percretism signs were the two most predictive MRI features of PAS. The area under the curve (AUC) of the predictive function was 0.833 (cutoff 0.39, 67% sensitivity, 100% specificity, p = 0.001). Percretism signs and myometrial thinning were the two most predictive MRI features of poor outcome. AUC of the predictive function was 0.971 (cutoff - 0.55, 100% sensitivity, 77% specificity, p < 0.001).

CONCLUSION

The diagnostic accuracy of MRI, especially considering the combination of the most predictive MRI findings, is higher when the target of the prediction is the clinical outcome rather than the PAS.

Diagnosis and management of placenta previa and low placental implantation

Objective: To evaluate the migration of low-placental implantation (LPI) during the third trimester of pregnancy and its effect on delivery and post-partum hemorrhage.Methods: We conducted a retrospective study at a level 3 maternity center including all cases of placenta previa (PP) and LPI between 1998 and 2014. The distance (d) between cervical internal os (CIO) and placental edge (PE) were measured by vaginal ultrasonography in the third trimester of pregnancy at 32 and 3 weeks after. We analyzed CIO-PE distance, volume of post-partum hemorrhage, delivery decision, and mode of delivery using Kruskall-Wallis test.Results: In total, 319 patients presented with PP or LPI. All complete PP (121) and 90.6% (58 of 64) of the placentas less than 1 cm from the CIO did not migrate. Among the 138 placentas with an initial CIO-PE d greater than 1 cm, only 17 (12.3%) did not migrate above 2 cm. The patients for whom the decision to perform a cesarean section (C-section) was retained and realized had a CIO-PE d significantly lower than those who delivered vaginally (p < .001). The patients who delivered by C-section had a lower CIO-PE d when an emergency C-section was performed, specifically for hemorrhage (p < .001). The mean volume of hemorrhage was significantly higher for patients with a CIO-PE d less than 2 cm.Conclusion: Complete PP and the majority of the placentas less than 1 cm from the CIO did not migrate. Above 1 cm, the majority of the placentas migrated three to four weeks later. For the placentas less than 1 cm from the CIO, a significant risk of hemorrhage at delivery was observed. Thus, prophylactic cesarean section is required for CIO-PE distances <1 cm. For distances between 1 and 2 cm, the volume of blood loss tends to be more important than for distances >3 cm without statistical significance. A vaginal delivery could be tried after information of patients.

Fetal interventional procedures and surgeries: a practical approach

The identification of congenital birth defects and fetal malformations continues to increase during the antenatal period with improved imaging techniques. Understanding of how to treat specific fetal conditions continues to improve outcomes from these treatment modalities. In an effort to further improvement in this field, we provide a review that begins with a brief background of fetal surgery including the history of fetal surgery, ethics surrounding fetal surgery, and considerations of how to treat the fetus during intervention. A synopsis of the most commonly encountered disease processes treated by fetal intervention/surgery including definitions, treatment modalities, and outcomes following fetal intervention/surgery is then provided. Within the sections describing each disease process, methodology is described that has helped with efficiency and success of procedures performed at our institution.

Second trimester marginal cord insertion is associated with adverse perinatal outcomes

Objectives: To determine the feasibility in visualizing placental cord insertion (PCI) during second-trimester fetal anatomical survey and the association between marginal cord insertion (MCI) and preterm delivery (PTD) and low birth weight (LBW). Our secondary objectives were to evaluate the association of MCI with adverse composite obstetrical and neonatal outcomes. Methods: A prospective cohort study was performed over a 28-month period. Women with singleton pregnancies presenting for routine anatomical survey between 18 and 22 weeks' gestation were included. PCI site was visualized on 2D grayscale and color Doppler and the shortest distance from the sagittal and transverse planes to the placental edge were recorded. MCI was diagnosed when any of measured distances was ≤2 cm. Correlations were assessed via bivariate chi-squared, independent t-test analyses and Fisher's exact tests. Regression models evaluated associations between MCI and adverse composite outcomes. Results: Three hundred one women were included and PCI was feasible in all cases. The incidence of MCI was 11.3% (n = 34). Baseline characteristics between those with and without MCI were similar, except for story of prior PTD, which was greater among those with MCI (17.65 versus 7.17%, p = .04). MCI was associated with increased likelihood of LBW (RR four; 95%CI, 1.46-10.99) and PTD (RR 3.2; 95%CI, 1.53-6.68); in multivariate analysis, we found associations between MCI and composite adverse obstetrical (RR 2.33; 95%CI, 1.30-4.19) and neonatal (RR 2.46; 95%CI, 1.26-4.81) outcomes. Conclusions: Evaluation of PCI is feasible in all cases. Second-trimester MCI is associated with increased likelihood for LBW, PTD, and composite adverse obstetrical and neonatal outcomes.

The Rate of Cervical Length Shortening in the Management of Vasa Previa

OBJECTIVES

There is no consensus about the optimal surveillance strategy in women with a diagnosis of vasa previa. The aim of this study was to evaluate the role of the rate of change in cervical length measurements in the management of singleton pregnancies with a diagnosis of vasa previa.

METHODS

We performed a retrospective case-control study of our databases for pregnancies with a prenatal diagnosis of vasa previa that were followed with transvaginal sonography for cervical length and evaluated the impact of the changes in cervical length on the need for emergency cesarean delivery.

RESULTS

The cohort included 29 singleton pregnancies with a prenatal diagnosis of vasa previa in the second trimester. There were 14 and 15 pregnancies that underwent elective and emergency cesarean delivery, respectively. The rate of cervical length shortening was significantly slower for women with elective compared to emergency cesarean delivery (median [range], 0.7 [0.1-2.0] versus 1.5 [0.25-3.0] mm/wk; P = .011). For each additional millimeter-per-week decrease in cervical length, the odds of emergency cesarean delivery increased by 6.50 (95% confidence interval, 1.02-41.20). The receiver operating characteristic curve for the rate of cervical length shortening in the prediction of emergency cesarean delivery yielded an area under the curve of 0.85 (95% confidence interval, 0.69-0.99).

CONCLUSIONS

Our findings indicate an association between the rate of cervical length shortening and the risk of emergency cesarean delivery in pregnancies with a diagnosis of vasa previa in the second trimester. Further multicentric studies are required to validate our data prospectively and, in particular, the role of serial cervical length measurements in determining the optimal delivery time for individual cases.

Handheld ultrasound to avert maternal and neonatal deaths in 2 regions of the Philippines: an iBuntis® intervention study

BACKGROUND

The major causes of maternal and neonatal mortality in the Philippines are hemorrhages and obstructed labor due to placental implantation abnormalities (PIAs), twin pregnancies and fetal malpresentations. All of which are all easily detected by ultrasound. However, women in rural areas and low-income groups do not have access to ultrasound during their prenatal care. We aimed to provide additional evidence on the benefits of handheld ultrasound (HU) for screening pregnancy related abnormalities in order to avert maternal and neonatal deaths.

METHODS

Using a HU, we trained community healthcare workers (CHWs) to identify 5 obstetrical conditions: fetal viability and number, placental localization, amniotic fluid volume (AFV) and fetal presentation. Women, between 20th and 24th weeks age of gestation from 2 regions of the Philippines, were scanned using the HU and the GE Logic 5 Premium ultrasound machine for validation. Maternal and neonatal deaths averted were estimated as health outcome measures of the study.

RESULTS

Four hundred sixty women were scanned of which 146 (31.7%) showed abnormal ultrasound readings consisting of 17 PIAs, 123 fetal malpresentation, 3 twins and 3 AFV abnormalities. The use of HU could have possibly averted 29 (6.3%) maternal deaths and 14.6% neonatal deaths at the time of delivery. Thirty-two out of the 460 women (~7%) delivered at home and 93% in hospitals or birthing facilities/lying-in centers. We observed approximately 95% agreement between the ultrasound readings of the trainees and the trainers, and 99% agreement between the readings made from the HU with the validation machine.

CONCLUSION

CHWs could be trained in the use of HU for scanning 5 obstetrical parameters. Early detection of abnormalities in these 5 obstetrical parameters can lead to early referral to facilities that are better equipped to manage obstetrical emergencies. Prenatal ultrasound can be an excellent point of care test for screening pregnant women at risk for possible complications and even death during labor and delivery.

TRIAL REGISTRATION

Thai Clinical Trial Registry identification number TCTR20171128004 , retrospectively registered November 28, 2017.

Placental implantation abnormalities: a modern approach

PURPOSE OF REVIEW

Placental implantation abnormalities (PIAs) comprise a large group of disorders associated with significant maternal, fetal, and neonatal morbidity.

RECENT FINDINGS

Risk factors include prior uterine surgery/myometrial scarring and the presence of placenta previa with or without prior cesarean delivery. Newly identified risk factors include previous prelabor cesarean delivery and previous postpartum hemorrhage. PIAs contribute substantially to preterm birth with prematurity rates ranging from 38 to 82%. Diagnosis is typically made by ultrasound in the second or third trimester; transvaginal ultrasound and color Doppler are useful in evaluating for placental invasion, placental edge thickness, presence of fetal vessels, and cervical length. Suggestive MRI features include increased vascularity, dark T2 bands, uterine bulging, thin or indistinct myometrium, and loss of dark T2 interface. An important first-trimester finding is the implantation of the gestational sac into prior hysterotomy scar (cesarean scar pregnancy). Recommendations for delivery are universally preterm and based on expert opinion. Proposed management strategies are outlined depending on cervical length, distance between internal cervical os and placenta, and placental edge thickness.

SUMMARY

There has been a recent shift in focus to individualizing management in order to improve delivery timing and in some cases even decrease risks associated with prematurity. There is a need for larger prospective studies or randomized trials to show that individualizing care can improve outcomes.

A new approach to fertility-preserving surgery in patients with placenta accreta

BACKGROUND

The aim of this study was to evaluate the efficacy of a novel combined surgical approach utilising: (1) two autonomous balloon Zhukovsky catheters (vaginal and uterine), (2) bilateral ligation of the descending uterine artery branches, (3) external supraplacental pleated sutures, and (4) either excision of a small area of placenta accreta or full metroplasty, for the management of uterine bleeding associated with placenta accreta of various severity.

MATERIALS AND METHODS

The study included medical records of 92 pregnant women with placenta accreta undergoing a caesarean section. To evaluate the efficacy of the proposed management strategy, study participants were divided into three groups. In Group 1 (controls, n = 47), we utilised the combination of bilateral ligation, Barinov external supraplacental pleated sutures, and either excision of the tightly attached portion of placenta accreta or metroplasty. In Group 2 (n = 20), the abovementioned surgical techniques were additionally combined with balloon tamponade using an intrauterine Zhukovsky catheter. In Group 3 (n = 25), we additionally used an intravaginal Zhukovsky balloon catheter to enhance the efficacy of intrauterine tamponade.

RESULTS

The use of an intrauterine balloon catheter combined with metroplasty was associated with a reduction in blood loss volume and blood transfusion rate by 1.9-fold, while the use of intravaginal balloon catheter reduced blood transfusion rate by 2.4-fold. The uterine balloon catheter reduced the risk of hysterectomy by 11-fold.

CONCLUSION

Simultaneous use of two Zhukovsky balloon catheters (intravaginal and intrauterine) during caesarean section facilitates fertility-preserving surgery in patients with placenta accreta even in the cases of low-segment bleeding, thereby representing a promising approach to management of these patients.

Integrative single-cell and cell-free plasma RNA transcriptomics elucidates placental cellular dynamics

The human placenta is a dynamic and heterogeneous organ critical in the establishment of the fetomaternal interface and the maintenance of gestational well-being. It is also the major source of cell-free fetal nucleic acids in the maternal circulation. Placental dysfunction contributes to significant complications, such as preeclampsia, a potentially lethal hypertensive disorder during pregnancy. Previous studies have identified significant changes in the expression profiles of preeclamptic placentas using whole-tissue analysis. Moreover, studies have shown increased levels of targeted RNA transcripts, overall and placental contributions in maternal cell-free nucleic acids during pregnancy progression and gestational complications, but it remains infeasible to noninvasively delineate placental cellular dynamics and dysfunction at the cellular level using maternal cell-free nucleic acid analysis. In this study, we addressed this issue by first dissecting the cellular heterogeneity of the human placenta and defined individual cell-type-specific gene signatures by analyzing more than 24,000 nonmarker selected cells from full-term and early preeclamptic placentas using large-scale microfluidic single-cell transcriptomic technology. Our dataset identified diverse cellular subtypes in the human placenta and enabled reconstruction of the trophoblast differentiation trajectory. Through integrative analysis with maternal plasma cell-free RNA, we resolved the longitudinal cellular dynamics of hematopoietic and placental cells in pregnancy progression. Furthermore, we were able to noninvasively uncover the cellular dysfunction of extravillous trophoblasts in early preeclamptic placentas. Our work showed the potential of integrating transcriptomic information derived from single cells into the interpretation of cell-free plasma RNA, enabling the noninvasive elucidation of cellular dynamics in complex pathological conditions.

Can 3-dimensional power Doppler indices improve the prenatal diagnosis of a potentially morbidly adherent placenta in patients with placenta previa?

BACKGROUND

Traditionally, 2-dimensional ultrasound parameters have been used for the diagnosis of a suspected morbidly adherent placenta previa. More objective techniques have not been well studied yet.

OBJECTIVE

The objective of the study was to determine the ability of prenatal 3-dimensional power Doppler analysis of flow and vascular indices to predict the morbidly adherent placenta objectively.

STUDY DESIGN

A prospective cohort study was performed in women between 28 and 32 gestational weeks with known placenta previa. Patients underwent a two-dimensional gray-scale ultrasound that determined management decisions. 3-Dimensional power Doppler volumes were obtained during the same examination and vascular, flow, and vascular flow indices were calculated after manual tracing of the viewed placenta in the sweep; data were blinded to obstetricians. Morbidly adherent placenta was confirmed by histology. Severe morbidly adherent placenta was defined as increta/percreta on histology, blood loss >2000 mL, and >2 units of PRBC transfused. Sensitivities, specificities, predictive values, and likelihood ratios were calculated. Student t and χ² tests, logistic regression, receiver-operating characteristic curves, and intra- and interrater agreements using Kappa statistics were performed.

RESULTS

The following results were found: (1) 50 women were studied: 23 had morbidly adherent placenta, of which 12 (52.2%) were severe morbidly adherent placenta; (2) 2-dimensional parameters diagnosed morbidly adherent placenta with a sensitivity of 82.6% (95% confidence interval, 60.4-94.2), a specificity of 88.9% (95% confidence interval, 69.7-97.1), a positive predictive value of 86.3% (95% confidence interval, 64.0-96.4), a negative predictive value of 85.7% (95% confidence interval, 66.4-95.3), a positive likelihood ratio of 7.4 (95% confidence interval, 2.5-21.9), and a negative likelihood ratio of 0.2 (95% confidence interval, 0.08-0.48); (3) mean values of the vascular index (32.8 ± 7.4) and the vascular flow index (14.2 ± 3.8) were higher in morbidly adherent placenta (P < .001); (4) area under the receiver-operating characteristic curve for the vascular and vascular flow indices were 0.99 and 0.97, respectively; (5) the vascular index ≥21 predicted morbidly adherent placenta with a sensitivity and a specificity of 95% (95% confidence interval, 88.2-96.9) and 91%, respectively (95% confidence interval, 87.5-92.4), 92% positive predictive value (95% confidence interval, 85.5-94.3), 90% negative predictive value (95% confidence interval, 79.9-95.3), positive likelihood ratio of 10.55 (95% confidence interval, 7.06-12.75), and negative likelihood ratio of 0.05 (95% confidence interval, 0.03-0.13); and (6) for the severe morbidly adherent placenta, 2-dimensional ultrasound had a sensitivity of 33.3% (95% confidence interval, 11.3-64.6), a specificity of 81.8% (95% confidence interval, 47.8-96.8), a positive predictive value of 66.7% (95% confidence interval, 24.1-94.1), a negative predictive value of 52.9% (95% confidence interval, 28.5-76.1), a positive likelihood ratio of 1.83 (95% confidence interval, 0.41-8.11), and a negative likelihood ratio of 0.81 (95% confidence interval, 0.52-1.26). A vascular index ≥31 predicted the diagnosis of a severe morbidly adherent placenta with a 100% sensitivity (95% confidence interval, 72-100), a 90% specificity (95% confidence interval, 81.7-93.8), an 88% positive predictive value (95% confidence interval, 55.0-91.3), a 100% negative predictive value (95% confidence interval, 90.9-100), a positive likelihood ratio of 10.0 (95% confidence interval, 3.93-16.13), and a negative likelihood ratio of 0 (95% confidence interval, 0-0.34). Intrarater and interrater agreements were 94% (P < .001) and 93% (P < .001), respectively.

CONCLUSION

The vascular index accurately predicts the morbidly adherent placenta in patients with placenta previa. In addition, 3-dimensional power Doppler vascular and vascular flow indices were more predictive of severe cases of morbidly adherent placenta compared with 2-dimensional ultrasound. This objective technique may limit the variations in diagnosing morbidly adherent placenta because of the subjectivity of 2-dimensional ultrasound interpretations.

Cervical Length in Patients at Risk for Placenta Accreta

OBJECTIVES

To evaluate cervical length measurements in women with placenta accreta compared to women with a nonadherent low-lying placenta or placenta previa and evaluate this relationship in terms of vaginal bleeding, preterm labor, and preterm birth.

METHODS

We conducted a retrospective cohort study between 1997 and 2011 of gravidas with more than 1 prior cesarean delivery who had a transvaginal ultrasound examination between 24 and 34 weeks for a low-lying placenta or placenta previa. Cervical length was measured from archived images in accordance with national guidelines by a single investigator, who was blinded to outcomes and ultrasound reports. The diagnosis of placental accreta was based on histologic confirmation. For study purposes, preterm birth was defined as less than 36 weeks, and cervical lengths of 3 cm or less were considered short. Standard statistical analyses were used.

RESULTS

A total of 125 patients met inclusion criteria. The cohort was divided into patients with (n = 43 [34%]) and without (n = 82 [66%]) placenta accreta and stratified by gestational age at the ultrasound examinations. Women with placenta accreta had shorter cervical length measurements during their 32- to 34-week ultrasound examinations (mean ± SD, 3.23 ± 0.98 versus 3.95 ± 1.0 cm; P < .01) and were more likely to have a short cervix of 3 cm or less (P = .001). However, these findings did not correlate with the degree of invasion (P = .3), or higher rates of vaginal bleeding and preterm labor (P = .19) resulting in preterm birth before 36 weeks (P = .64).

CONCLUSIONS

Women with placenta accreta had shorter cervical lengths at 32 to 34 weeks than women with a nonadherent low-lying placenta or placenta previa, but this finding did not correlate with a higher risk of vaginal bleeding or preterm labor resulting in preterm birth before 36 weeks.

Prenatal diagnosis and management of vasa previa in twin pregnancies: a case series and systematic review

BACKGROUND

Twin pregnancies are at higher risks of velamentous cord insertion and vasa previa. In vitro fertilization is an additional risk factor of abnormal cord insertion and thus the incidence of vasa previa is likely to increase over the next decades.

OBJECTIVE

We sought to evaluate the role of ultrasound imaging in optimizing the management of twins diagnosed with vasa previa antenatally.

STUDY DESIGN

We searched our database for twin pregnancies diagnosed with vasa previa and managed antenatally using measurements of cervical length and performed a systematic review of articles that correlated prenatal diagnosis of vasa previa in twins and pregnancy outcome. PubMed and MEDLINE were searched for studies published from 1987 through October 20, 2016, using specific medical subject heading terms, key words, and their combination. The primary eligibility criteria were articles that correlated prenatal ultrasound imaging of vasa previa and pregnancy outcome in twins. The secondary eligibility criteria was the use of cervical length in the management of twin pregnancies diagnosed antenatally with vasa previa. Two authors independently assessed inclusion criteria, data extraction, and analysis. The final selection included 3 case report series, 9 retrospective cohort studies, and 1 retrospective case-control study of vasa previa diagnosed prenatally and confirmed at birth in twin pregnancies.

RESULTS

The search of our databases identified 6 cases of dichorionic-diamniotic twins and 1 case of monochorionic-diamniotic twins diagnosed prenatally with vasa previa between 22-29 weeks and managed using cervical length. Two cases were delivered by emergency because of rapid changes in cervical length in one and bleeding on placenta previa in the other at 33 and 30 weeks, respectively. The systematic review identified data on 56 cases. The incidence of twin pregnancies diagnosed antenatally with vasa previa in the cohort and case-control studies was 11.0%. Data on chorionicity were available in only 34 cases and cervical length measurements were used by only the authors of 2 case reports and 4 cohort studies. Velamentous cord insertion was the most common additional ultrasound findings in twins presenting with vasa previa in both our series and the systematic review.

CONCLUSION

Vasa previa is associated with specific prenatal and obstetric complications with different outcomes in singletons compared to twins. Data on the diagnosis and management of vasa previa in twin pregnancies are limited but there is enough evidence to warrant guidelines for targeted screening. To enable the development of efficient management protocols tailored to the need of individual cases, future studies of the screening, diagnosis, and management of vasa previa should be prospective and multicentric with detailed data on twins including chorionicity and use of cervical length.