Fetal umbilical artery Doppler to predict compromise of fetal/neonatal wellbeing in a high-risk population: systematic review and bivariate meta-analysis

Effects of thalassemia minor on umbilical artery blood flow and perinatal outcomes in pregnancy: A retrospective cohort study

OBJECTIVE

The aim of the present study was to compare the fetal umbilical artery blood flow parameters in the third trimester and perinatal outcomes between pregnant women with and without thalassemia minor in South China.

METHODS

This was a retrospective cohort study. Doppler ultrasound was used to detect fetal umbilical artery hemodynamics in pregnant women with or without thalassemia minor during the third trimester. The main parameters assessed were umbilical artery peak systolic flow velocity/end-diastolic flow velocity (S/D), resistance index (RI), pulsation index (PI), and relevant perinatal outcomes.

RESULTS

This study included 540 pregnant women, 180 with thalassemia minor and 360 being healthy controls. In the third trimester, the thalassemia minor group had higher umbilical artery S/D (P = 0.002), RI (P = 0.002), and PI (P = 0.012) than healthy pregnant women, as well as lower levels of hemoglobin (Hb) (P < 0.001) and higher ferritin levels (P < 0.001). Compared to the non-thalassemia group, neonatal body weight in the thalassemia minor group was significantly lower (P = 0.001). Additionally, the incidence of maternal anemia (odds ratio [OR] 3.92; 95% confidence interval [CI]: 2.57-5.99, P < 0.001), low birth weight (OR 15.35; 95% CI: 1.71-137.93, P = 0.015), fetal distress (OR 2.18; 95% CI: 1.12-4.26, P = 0.023), neonatal asphyxia (OR 12.81; 95% CI: 1.40-117.33, P = 0.024), oligohydramnios (OR 18.25; 95% CI: 2.21-150.36, P = 0.007) and Apgar score <7 at 1 min after birth (OR 7.97; 95% CI: 1.53-41.54, P = 0.014) was significantly higher in the thalassemia minor group.

CONCLUSION

Pregnant women with thalassemia minor have higher umbilical artery S/D, RI and PI during the third trimester and a higher risk of adverse perinatal outcomes.

The association between discordant umbilical arterial resistance in growth-restricted fetuses and adverse outcomes

BACKGROUND

Assessing the umbilical artery pulsatility index via Doppler measurements plays a crucial role in evaluating fetal growth impairment.

OBJECTIVE

This study aimed to investigate perinatal outcomes associated with discordant pulsatility indices of umbilical arteries in fetuses with growth restriction.

STUDY DESIGN

In this retrospective cohort study, all singleton pregnancies were included if their estimated fetal weight and/or abdominal circumference fell below the 10th percentile for gestational age (2017-2022). Eligible cases included singleton pregnancies with concurrent sampling of both umbilical arteries within 14 days of birth at the ultrasound evaluation closest to delivery. The exclusion criteria included births before 22 weeks of gestation, evidence of absent or reverse end-diastolic flow in either umbilical artery, and known fetal genetic or structural anomalies. The study compared cases with discordant umbilical artery pulsatility index values (defined as 1 umbilical artery pulsatility index at ≤95th percentile and the other umbilical artery pulsatility index at >95th percentile for gestational age) to pregnancies where both umbilical artery pulsatility indices had normal pulsatility index values and those with both umbilical arteries displaying abnormal pulsatility index values. The primary outcome assessed was the occurrence of composite adverse neonatal outcomes. Multivariable logistic regressions were performed, adjusting for relevant covariates.

RESULTS

The study encompassed 1014 patients, including 194 patients (19.1%) with discordant umbilical artery pulsatility index values among those who had both umbilical arteries sampled close to delivery, 671 patients (66.2%) with both umbilical arteries having normal pulsatility index values, and 149 patients (14.7%) with both umbilical arteries exhibiting abnormal values. Pregnancies with discordant umbilical artery pulsatility index values displayed compromised sonographic parameters compared with those with both umbilical arteries showing normal pulsatility index values. Similarly, the number of abnormal umbilical artery pulsatility index values was associated with adverse perinatal outcomes in a dose-response manner. Cases with 1 abnormal (discordant) umbilical artery pulsatility index value showed favorable sonographic parameters and perinatal outcomes compared with cases with both abnormal umbilical artery pulsatility index values, and cases with both abnormal umbilical artery pulsatility index values showed worse sonographic parameters and perinatal outcomes compared with cases with discordant UA PI values. Multivariate analysis revealed that discordant umbilical artery pulsatility indices were significantly and independently associated with composite adverse perinatal outcomes, with an adjusted odds ratio of 1.75 (95% confidence interval, 1.24-2.47; P = .002).

CONCLUSION

Evaluating the resistance indices of both umbilical arteries may provide useful data and assist in assessing adverse perinatal outcomes among fetuses with growth restriction.

Fetal Growth Restriction: A Comprehensive Review of Major Guidelines

Importance

Fetal growth restriction (FGR) is a common pregnancy complication and a significant contributor of fetal and neonatal morbidity and mortality, mainly due to the lack of effective screening, prevention, and management policies.

Objective

The aim of this study was to review and compare the most recently published influential guidelines on the management of pregnancies complicated by FGR.

Evidence Acquisition

A descriptive review of guidelines from the American College of Obstetricians and Gynecologists (ACOG), the Society for Maternal-Fetal Medicine, the International Federation of Gynecology and Obstetrics, the International Society of Ultrasound in Obstetrics and Gynecology, the Royal College of Obstetricians and Gynecologists, the Society of Obstetricians and Gynecologists of Canada (SOGC), the Perinatal Society of Australia and New Zealand, the Royal College of Physicians of Ireland, the French College of Gynecologists and Obstetricians (FCGO), and the German Society of Gynecology and Obstetrics on FGR was carried out.

Results

Several discrepancies were identified regarding the definition of FGR and small-for-gestational-age fetuses, the diagnostic criteria, and the need of testing for congenital infections. On the contrary, there is an overall agreement among the reviewed guidelines regarding the importance of early universal risk stratification for FGR to accordingly modify the surveillance protocols. Low-risk pregnancies should unanimously be evaluated by serial symphysis fundal height measurement, whereas the high-risk ones warrant increased sonographic surveillance. Following FGR diagnosis, all medical societies agree that umbilical artery Doppler assessment is required to further guide management, whereas amniotic fluid volume evaluation is also recommended by the ACOG, the SOGC, the Perinatal Society of Australia and New Zealand, the FCGO, and the German Society of Gynecology and Obstetrics. In case of early, severe FGR or FGR accompanied by structural abnormalities, the ACOG, the Society for Maternal-Fetal Medicine, the International Federation of Gynecology and Obstetrics, the Royal College of Obstetricians and Gynecologists, the SOGC, and the FCGO support the performance of prenatal diagnostic testing. Consistent protocols also exist on the optimal timing and mode of delivery, the importance of continuous fetal heart rate monitoring during labor, and the need for histopathological examination of the placenta after delivery. On the other hand, guidelines concerning the frequency of fetal growth and Doppler velocimetry evaluation lack uniformity, although most of the reviewed medical societies recommend an average interval of 2 weeks, reduced to weekly or less when umbilical artery abnormalities are detected. Moreover, there is a discrepancy on the appropriate timing for corticosteroids and magnesium sulfate administration, as well as the administration of aspirin as a preventive measure. Cessation of smoking, alcohol consumption, and illicit drug use are proposed as preventive measures to reduce the incidence of FGR.

Conclusions

Fetal growth restriction is a clinical entity associated with numerous adverse antenatal and postnatal events, but currently, it has no definitive cure apart from delivery. Thus, the development of uniform international protocols for the early recognition, the adequate surveillance, and the optimal management of growth-restricted fetuses seem of paramount importance to safely guide clinical practice, thereby improving perinatal outcomes of such pregnancies.

Maternal PlGF and umbilical Dopplers predict pregnancy outcomes at diagnosis of early-onset fetal growth restriction

BACKGROUNDSevere, early-onset fetal growth restriction (FGR) causes significant fetal and neonatal mortality and morbidity. Predicting the outcome of affected pregnancies at the time of diagnosis is difficult, thus preventing accurate patient counseling. We investigated the use of maternal serum protein and ultrasound measurements at diagnosis to predict fetal or neonatal death and 3 secondary outcomes: fetal death or delivery at or before 28+0 weeks, development of abnormal umbilical artery (UmA) Doppler velocimetry, and slow fetal growth.METHODSWomen with singleton pregnancies (n = 142, estimated fetal weights [EFWs] below the third centile, less than 600 g, 20+0 to 26+6 weeks of gestation, no known chromosomal, genetic, or major structural abnormalities) were recruited from 4 European centers. Maternal serum from the discovery set (n = 63) was analyzed for 7 proteins linked to angiogenesis, 90 additional proteins associated with cardiovascular disease, and 5 proteins identified through pooled liquid chromatography and tandem mass spectrometry. Patient and clinician stakeholder priorities were used to select models tested in the validation set (n = 60), with final models calculated from combined data.RESULTSThe most discriminative model for fetal or neonatal death included the EFW z score (Hadlock 3 formula/Marsal chart), gestational age, and UmA Doppler category (AUC, 0.91; 95% CI, 0.86-0.97) but was less well calibrated than the model containing only the EFW z score (Hadlock 3/Marsal). The most discriminative model for fetal death or delivery at or before 28+0 weeks included maternal serum placental growth factor (PlGF) concentration and UmA Doppler category (AUC, 0.89; 95% CI, 0.83-0.94).CONCLUSIONUltrasound measurements and maternal serum PlGF concentration at diagnosis of severe, early-onset FGR predicted pregnancy outcomes of importance to patients and clinicians.TRIAL REGISTRATIONClinicalTrials.gov NCT02097667.FUNDINGThe European Union, Rosetrees Trust, Mitchell Charitable Trust.

Comparison of ductus venosus Doppler and cerebroplacental ratio for the prediction of adverse perinatal outcome in high-risk pregnancies before and after 34 weeks

INTRODUCTION

The objective of the study was to compare the accuracy of the ductus venosus pulsatility index (DV PI) with that of the cerebroplacental ratio (CPR) for the prediction of adverse perinatal outcome at two gestational ages: <34 and ≥34 weeks' gestation.

MATERIAL AND METHODS

This was a retrospective study of 169 high-risk pregnancies (72 < 34 and 97 ≥ 34 weeks) that underwent an ultrasound examination of CPR, DV Doppler and estimated fetal weight at 22-40 weeks. The CPR and DV PI were converted into multiples of the median, and the estimated fetal weight into centiles according to local references. Adverse perinatal outcome was defined as a composite of abnormal cardiotocogram, intrapartum pH requiring cesarean delivery, 5' Apgar score <7, neonatal pH <7.10 and admission to neonatal intensive care unit. Values were plotted according to the interval to labor to evaluate progression of abnormal Doppler values, and their accuracy was evaluated at both gestational periods, alone and combined with clinical data, by means of univariable and multivariable models, using the Akaike information criteria (AIC) and the area under the curve (AUC).

RESULTS

Prior to 34 weeks' gestation, DV PI was the latest parameter to become abnormal. However, it was a poor predictor of adverse perinatal outcome (AUC 0.56, 95% CI: 0.40-0.71, AIC 76.2, p > 0.05), and did not improve the predictive accuracy of CPR for adverse perinatal outcome (AUC 0.88, 95% CI: 0.79-0.97, AIC 52.9, p < 0.0001). After 34 weeks' gestation, the chronology of the DV PI and CPR anomalies overlapped, but again DV PI was a poor predictor for adverse perinatal outcome (AUC 0.62, 95% CI: 0.49-0.74, AIC 120.6, p > 0.05), that did not improve the CPR ability to predict adverse perinatal outcome (AUC 0.80, 95% CI: 0.67-0.92, AIC 106.8, p < 0.0001). The predictive accuracy of CPR prior to 34 weeks persisted when the gestational age at delivery was included in the model (AUC 0.91, 95% CI: 0.81-1.00, AIC 46.3, p < 0.0001, versus AUC 0.86, 95% CI: 0.72-1, AIC 56.1, p < 0.0001), and therefore was not determined by prematurity.

CONCLUSIONS

CPR predicts adverse perinatal outcome better than DV PI, regardless of gestational age. Larger prospective studies are needed to delineate the role of ultrasound tools of fetal wellbeing assessment in predicting and preventing adverse perinatal outcome.

Doppler Ultrasound of the Umbilical Artery: Clinical Application

OBJECTIVE

 To provide a survey of relevant literature on umbilical artery Doppler ultrasound use in clinical practice, technical considerations and limitations, and future perspectives.

METHODS

 Literature searches were conducted in PubMed and Medline, restricted to articles written in English. Additionally, the references of all analyzed studies were searched to obtain necessary information.

RESULTS

 The use of this technique as a routine surveillance method is only recommended for high-risk pregnancies with impaired placentation. Meta-analyses of randomized trials have established that obstetric management guided by umbilical artery Doppler findings can improve perinatal mortality and morbidity. The values of the indices of Umbilical artery Doppler decrease with advancing gestational age; however, a lack of consensus on reference ranges prevails.

CONCLUSION

 Important clinical decisions are based on the information obtained with umbilical artery Doppler ultrasound. Future efforts in research are imperative to overcome the current limitations of the technique.

Interpretation of wave reflections in the umbilical arterial segment of the feto-placental circulation: computational modeling of the feto-placental arterial tree

Placental vascular abnormalities are associated with a host of pregnancy complications including placenta mediated fetal growth restriction (FGR). Umbilical arterial (UA) Doppler ultrasound velocity waveforms are widely used in the diagnosis of underlying placental vascular abnormalities in pregnancies with suspected FGR, which greatly help prevent stillbirth via ongoing fetal monitoring and timely delivery. However, the sensitivity of UA Doppler diagnosis diminishes late in gestation. Our goal was to present a generalized wave decomposition method to compute forward and reflected components from UA waveforms. A detailed anatomical based model was also developed to explain observed UA flow waveform and to explore how vascular properties affect the shape of flow wave components. Using pregnant mice and high frequency ultrasound microscopy, we obtained in utero Doppler and M- mode ultrasound measurements in 15 fetuses UA. Following ultrasound, the placentas were collected and perfused with contrast agent to obtain high-resolution 3D images of the feto-placental arteries. Model results indicate the significant role of terminal load impedance (capillary and/or veins) in creating positive or negative reflected waveforms. A negative reflected waveform is obtained when terminal impedance increases. This is consistent with the elongated and non-branching terminal villi that are proposed cause the highly abnormal UA waveforms found in early-onset FGR. The significance of these findings for the diagnostic utility of UA Doppler in human pregnancy is that the identification and measurement of wave reflections may aid in discriminating between healthy and abnormal placental vasculature in pregnancies with suspected late-onset FGR.

Fetal umbilical artery Doppler as a tool for universal third trimester screening: A systematic review and meta-analysis of diagnostic test accuracy

The objective of this study was to investigate the accuracy of universal third trimester umbilical artery (UA) Doppler to predict adverse pregnancy outcome at term. We searched Medline, EMBASE, the Cochrane library and ClinicalTrials.gov from inception to October 2020 and we also analyzed previously unpublished data from a prospective cohort study of nulliparous women, the Pregnancy Outcome Prediction (POP) study. We included studies that performed a third-trimester ultrasound scan in unselected, low or mixed risk populations, excluding studies which only included high risk pregnancies. Meta-analysis was performed using the hierarchal summary receiver operating characteristic curve (HSROC) analysis and bivariate logit-normal models. We identified 13 studies (including the POP study) involving 67,764 pregnancies which met our inclusion criteria. The overall quality was variable and only six studies (N = 5777 patients) blinded clinicians to the UA Doppler result. The summary sensitivity and positive likelihood ratio (LR) for small for gestational age (SGA; birthweight <10th centile) were 21.7% (95% CI 13.2-33.6%) and 2.65 (95% CI 1.89-3.72) respectively. The summary positive LR for NICU admission and metabolic acidosis were 1.35 (95% CI 0.93-1.97) and 1.34 (95% CI 0.86-2.08) respectively. The results were similar in the POP study: associations with SGA (positive LR 2.66 [95% CI 2.11-3.36]) and severe SGA (birthweight <3rd centile; positive LR 3.27 [95% CI 2.29-4.68]) but no statistically significant association with neonatal morbidity. We conclude that third trimester UA Doppler has moderate predictive accuracy for small for gestational age but not for indicators of neonatal morbidity in unselected and low risk pregnancies.

Fetal Growth Restriction: ACOG Practice Bulletin, Number 227

Fetal growth restriction, also known as intrauterine growth restriction, is a common complication of pregnancy that has been associated with a variety of adverse perinatal outcomes. There is a lack of consensus regarding terminology, etiology, and diagnostic criteria for fetal growth restriction, with uncertainty surrounding the optimal management and timing of delivery for the growth-restricted fetus. An additional challenge is the difficulty in differentiating between the fetus that is constitutionally small and fulfilling its growth potential and the small fetus that is not fulfilling its growth potential because of an underlying pathologic condition. The purpose of this document is to review the topic of fetal growth restriction with a focus on terminology, etiology, diagnostic and surveillance tools, and guidance for management and timing of delivery.

FIGO (international Federation of Gynecology and obstetrics) initiative on fetal growth: best practice advice for screening, diagnosis, and management of fetal growth restriction

Fetal growth restriction (FGR) is defined as the failure of the fetus to meet its growth potential due to a pathological factor, most commonly placental dysfunction. Worldwide, FGR is a leading cause of stillbirth, neonatal mortality, and short- and long-term morbidity. Ongoing advances in clinical care, especially in definitions, diagnosis, and management of FGR, require efforts to effectively translate these changes to the wide range of obstetric care providers. This article highlights agreements based on current research in the diagnosis and management of FGR, and the areas that need more research to provide further clarification of recommendations. The purpose of this article is to provide a comprehensive summary of available evidence along with practical recommendations concerning the care of pregnancies at risk of or complicated by FGR, with the overall goal to decrease the risk of stillbirth and neonatal mortality and morbidity associated with this condition. To achieve these goals, FIGO (the International Federation of Gynecology and Obstetrics) brought together international experts to review and summarize current knowledge of FGR. This summary is directed at multiple stakeholders, including healthcare providers, healthcare delivery organizations and providers, FIGO member societies, and professional organizations. Recognizing the variation in the resources and expertise available for the management of FGR in different countries or regions, this article attempts to take into consideration the unique aspects of antenatal care in low-resource settings (labelled “LRS” in the recommendations). This was achieved by collaboration with authors and FIGO member societies from low-resource settings such as India, Sub-Saharan Africa, the Middle East, and Latin America.

Study of the Development of Placental Microvascularity by Doppler SMI (Superb Microvascular Imaging): A Reality Today

Our objective was to evaluate the development of placental vascularization in normal gestation by using Doppler superb microvascular imaging (SMI). The fetal and maternal parameters of 20 pregnant women without pathology were evaluated at weeks 12, 16, 20-22, 24-26, 28-30, 32-34, 36-38 and 40-42. Doppler SMI was used to evaluate the placental vascularization (pulsatile index and peak systolic velocity) of the primary, secondary and tertiary (third) villi, and qualitative placental descriptions and anatomic-pathologic studies of these placentas were performed. The number of cotyledons identified by Doppler SMI increased from two between weeks 16 and 18 to 24 between weeks 28 and 38. The secondary and tertiary villi began developing at 20 wk of gestation. The pulsatile index of the primary villi remained constant (0.8-0.9 in all pregnancies). The pulsatile index of the secondary and tertiary villi increased from 1.1 to 1.53 and from 1.4 to 1.68, respectively. The peak systolic velocity underwent a significant increase throughout gestation in the secondary and tertiary villi (9.2 to 34.9 cm/s and 7.5 to 52.9 cm/s, respectively). We evaluated the development of placental microvascularization using Doppler SMI in pregnancies without pathology and describe normal placental Doppler SMI findings.

Quantification of Wave Reflection in the Human Umbilical Artery From Asynchronous Doppler Ultrasound Measurements

Elevated umbilical artery pulsatility is a widely used biomarker for placental pathology leading to intra-uterine growth restriction and, in severe cases, still-birth. It has been hypothesized that placental pathology modifies umbilical artery pulsatility by altering the degree to which the pulse pressure wave, which originates from the fetal heart, is reflected from the placental vasculature to interfere with the incident wave. Here we present a method for estimating the reflected pulse wave in the umbilical artery of human fetuses using asynchronously acquired Doppler ultrasound measurements from the two ends of the umbilical cord. This approach assumes non-dispersive and loss-less propagation of the waves along the artery and models the reflection process as a linear system with a parameterized impulse response. Model parameters are determined from the measured Doppler waveforms by constrained optimization. Velocity waveforms were obtained from 142 pregnant volunteers where 123 met data quality criteria in at least one umbilical artery. The reflection model was consistent with the measured waveforms in 183 of 212 arteries that were analyzed. The analysis method was validated by applying it to simulated datasets and comparing solutions to ground-truth. With measurement noise levels typical of clinical ultrasound, parameters describing the reflected wave were accurately determined.

Advances in imaging feto-placental vasculature: new tools to elucidate the early life origins of health and disease

Optimal placental function is critical for fetal development, and therefore a crucial consideration for understanding the developmental origins of health and disease (DOHaD). The structure of the fetal side of the placental vasculature is an important determinant of fetal growth and cardiovascular development. There are several imaging modalities for assessing feto-placental structure including stereology, electron microscopy, confocal microscopy, micro-computed tomography, light-sheet microscopy, ultrasonography and magnetic resonance imaging. In this review, we present current methodologies for imaging feto-placental vasculature morphology ex vivo and in vivo in human and experimental models, their advantages and limitations and how these provide insight into placental function and fetal outcomes. These imaging approaches add important perspective to our understanding of placental biology and have potential to be new tools to elucidate a deeper understanding of DOHaD.

Does Uterine Doppler Add Information to the Cerebroplacental Ratio for the Prediction of Adverse Perinatal Outcome at the End of Pregnancy?

OBJECTIVE

To evaluate whether the addition of the mean uterine arteries pulsatility index (mUtA PI) to the cerebroplacental ratio (CPR) improves its ability to predict adverse perinatal outcome (APO) at the end of pregnancy.

METHODS

This was a prospective study of 891 fetuses that underwent an ultrasound examination at 34-41 weeks. The CPR and the mUtA PI were converted into multiples of the median (MoM) and the estimated fetal weight (EFW) into centiles according to local references. APO was defined as a composite of abnormal cardiotocogram, intrapartum pH requiring cesarean section, 5' Apgar score <7, neonatal pH <7.10 and admission to pediatric care units. The accuracies of the different parameters were evaluated alone and in combination with gestational characteristics using univariate and multivariate analyses by means of the Akaike Information Criteria (AIC) and the area under the curve (AUC). Finally, a comparison was similarly performed between the CPR and the cerebro-placental-uterine ratio (CPUR; CPR/mUtA PI) for the prediction of APO.

RESULTS

The univariate analysis showed that CPR MoM was the best parameter predicting APO (AIC 615.71, AUC 0.675). The multivariate analysis including clinical data showed that the best prediction was also achieved with the CPR MoM (AIC 599.39, AUC 0.718). Moreover, when EFW centiles were considered, the addition of UtA PI MoM did not improve the prediction already obtained with CPR MoM (AIC 591.36, AUC 0.729 vs. AIC 589.86, AUC 0.731). Finally, the prediction by means of CPUR did not improve that of CPR alone (AIC 623.38, AUC 0.674 vs. AIC 623.27, AUC 0.66).

CONCLUSION

The best prediction of APO at the end of pregnancy is obtained with CPR whatever is the combination of parameters. The addition of uterine Doppler to the information yielded by CPR does not result in any prediction improvement.

Biochemical tests of placental function versus ultrasound assessment of fetal size for stillbirth and small-for-gestational-age infants

BACKGROUND

Stillbirth affects 2.6 million pregnancies worldwide each year. Whilst the majority of cases occur in low- and middle-income countries, stillbirth remains an important clinical issue for high-income countries (HICs) - with both the UK and the USA reporting rates above the mean for HICs. In HICs, the most frequently reported association with stillbirth is placental dysfunction. Placental dysfunction may be evident clinically as fetal growth restriction (FGR) and small-for-dates infants. It can be caused by placental abruption or hypertensive disorders of pregnancy and many other disorders and factorsPlacental abnormalities are noted in 11% to 65% of stillbirths. Identification of FGA is difficult in utero. Small-for-gestational age (SGA), as assessed after birth, is the most commonly used surrogate measure for this outcome. The degree of SGA is associated with the likelihood of FGR; 30% of infants with a birthweight < 10th centile are thought to be FGR, while 70% of infants with a birthweight < 3rd centile are thought to be FGR. Critically, SGA is the most significant antenatal risk factor for a stillborn infant. Correct identification of SGA infants is associated with a reduction in the perinatal mortality rate. However, currently used tests, such as measurement of symphysis-fundal height, have a low reported sensitivity and specificity for the identification of SGA infants.

OBJECTIVES

The primary objective was to assess and compare the diagnostic accuracy of ultrasound assessment of fetal growth by estimated fetal weight (EFW) and placental biomarkers alone and in any combination used after 24 weeks of pregnancy in the identification of placental dysfunction as evidenced by either stillbirth, or birth of a SGA infant. Secondary objectives were to investigate the effect of clinical and methodological factors on test performance.

SEARCH METHODS

We developed full search strategies with no language or date restrictions. The following sources were searched: MEDLINE, MEDLINE In Process and Embase via Ovid, Cochrane (Wiley) CENTRAL, Science Citation Index (Web of Science), CINAHL (EBSCO) with search strategies adapted for each database as required; ISRCTN Registry, UK Clinical Trials Gateway, WHO International Clinical Trials Portal and ClinicalTrials.gov for ongoing studies; specialist abstract and conference proceeding resources (British Library's ZETOC and Web of Science Conference Proceedings Citation Index). Search last conducted in Ocober 2016.

SELECTION CRITERIA

We included studies of pregnant women of any age with a gestation of at least 24 weeks if relevant outcomes of pregnancy (live birth/stillbirth; SGA infant) were assessed. Studies were included irrespective of whether pregnant women were deemed to be low or high risk for complications or were of mixed populations (low and high risk). Pregnancies complicated by fetal abnormalities and multi-fetal pregnancies were excluded as they have a higher risk of stillbirth from non-placental causes. With regard to biochemical tests, we included assays performed using any technique and at any threshold used to determine test positivity.

DATA COLLECTION AND ANALYSIS

We extracted the numbers of true positive, false positive, false negative, and true negative test results from each study. We assessed risk of bias and applicability using the QUADAS-2 tool. Meta-analyses were performed using the hierarchical summary ROC model to estimate and compare test accuracy.

MAIN RESULTS

We included 91 studies that evaluated seven tests - blood tests for human placental lactogen (hPL), oestriol, placental growth factor (PlGF) and uric acid, ultrasound EFW and placental grading and urinary oestriol - in a total of 175,426 pregnant women, in which 15,471 pregnancies ended in the birth of a small baby and 740 pregnancies which ended in stillbirth. The quality of included studies was variable with most domains at low risk of bias although 59% of studies were deemed to be of unclear risk of bias for the reference standard domain. Fifty-three per cent of studies were of high concern for applicability due to inclusion of only high- or low-risk women.Using all available data for SGA (86 studies; 159,490 pregnancies involving 15,471 SGA infants), there was evidence of a difference in accuracy (P < 0.0001) between the seven tests for detecting pregnancies that are SGA at birth. Ultrasound EFW was the most accurate test for detecting SGA at birth with a diagnostic odds ratio (DOR) of 21.3 (95% CI 13.1 to 34.6); hPL was the most accurate biochemical test with a DOR of 4.78 (95% CI 3.21 to 7.13). In a hypothetical cohort of 1000 pregnant women, at the median specificity of 0.88 and median prevalence of 19%, EFW, hPL, oestriol, urinary oestriol, uric acid, PlGF and placental grading will miss 50 (95% CI 32 to 68), 116 (97 to 133), 124 (108 to 137), 127 (95 to 152), 139 (118 to 154), 144 (118 to 161), and 144 (122 to 161) SGA infants, respectively. For the detection of pregnancies ending in stillbirth (21 studies; 100,687 pregnancies involving 740 stillbirths), in an indirect comparison of the four biochemical tests, PlGF was the most accurate test with a DOR of 49.2 (95% CI 12.7 to 191). In a hypothetical cohort of 1000 pregnant women, at the median specificity of 0.78 and median prevalence of 1.7%, PlGF, hPL, urinary oestriol and uric acid will miss 2 (95% CI 0 to 4), 4 (2 to 8), 6 (6 to 7) and 8 (3 to 13) stillbirths, respectively. No studies assessed the accuracy of ultrasound EFW for detection of pregnancy ending in stillbirth.

AUTHORS' CONCLUSIONS

Biochemical markers of placental dysfunction used alone have insufficient accuracy to identify pregnancies ending in SGA or stillbirth. Studies combining U and placental biomarkers are needed to determine whether this approach improves diagnostic accuracy over the use of ultrasound estimation of fetal size or biochemical markers of placental dysfunction used alone. Many of the studies included in this review were carried out between 1974 and 2016. Studies of placental substances were mostly carried out before 1991 and after 2013; earlier studies may not reflect developments in test technology.

Placental vascular abnormalities in the mouse alter umbilical artery wave reflections

Current methods to detect placental vascular pathologies that monitor Doppler ultrasound changes in umbilical artery (UA) pulsatility have only moderate diagnostic utility, particularly in late gestation. In fetal mice, we recently demonstrated that reflected pressure waves propagate counter to the direction of flow in the UA and proposed the measurement of these reflections as a means to detect abnormalities in the placental circulation. In the present study, we used this approach in combination with microcomputed tomography to investigate the relationship between altered placental vascular architecture and changes in UA wave reflection metrics. Fetuses were assessed at embryonic day (E) 15.5 and E17.5 in control C57BL6/J mice and dams treated with combination antiretroviral therapy (cART), a known model of fetal growth restriction. Whereas the reflection coefficient was not different between groups at E15.5, it was 27% higher at E17.5 in cART-treated mice compared with control mice. This increase in reflection coefficient corresponded to a 36% increase in the total number of vessel segments, a measure of overall architectural complexity. Interestingly, there was no difference in UA pulsatility index between groups, suggesting that the wave reflections convey information about vascular architecture that is not captured by conventional ultrasound metrics. The wave reflection parameters were found to be associated with the morphology of the fetoplacental arterial tree, with the area ratio between the UA and first branch points correlating with the reflection coefficient. This study highlights the potential for wave reflection to aid in the noninvasive clinical assessment of placental vascular pathology. NEW & NOTEWORTHY We used a novel ultrasound methodology based on detecting pulse pressure waves that propagate along the umbilical artery to investigate the relationship between changes in wave reflection metrics and altered placental vascular architecture visualized by microcomputed tomography. Using pregnant mice treated with combination antiretroviral therapy, a model of fetal growth restriction, we demonstrated that reflections in the umbilical artery are sensitive to placental vascular abnormalities and associated with the geometry of the fetoplacental tree.

Fetal dynamic phase-contrast MR angiography using ultrasound gating and comparison with Doppler ultrasound measurements

OBJECTIVES

To investigate the feasibility of fetal phase-contrast (PC)-MR angiography of the descending aorta (AoD) using an MR-compatible Doppler ultrasound sensor (DUS) for fetal cardiac gating and to compare velocimetry with Doppler ultrasound measurements.

METHODS

In this prospective study, 2D PC-MR angiography was performed in 12 human fetuses (mean gestational age 32.8 weeks) using an MR-compatible DUS for gating of the fetal heart at 1.5 T. Peak flow velocities in the fetal AoD were compared with Doppler ultrasound measurements performed on the same day. Reproducibility of PC-MR measurements was tested by repeated PC-MR in five fetuses.

RESULTS

Dynamic PC-MR angiography in the AoD was successfully performed in all fetuses using the DUS, with an average fetal heart rate of 140 bpm (range 129-163). Time-velocity curves revealed typical arterial blood flow patterns. PC-MR mean flow velocity and mean flux were 21.2 cm/s (range 8.6-36.8) and 8.4 ml/s (range 3.2-14.6), respectively. A positive association between PC-MR mean flux and stroke volume with gestational age was obtained (r = 0.66, p = 0.02 and r = 0.63, p = 0.03). PC-MR and Doppler ultrasound peak velocities revealed a highly significant correlation (r = 0.8, p < 0.002). Peak velocities were lower for PC-MR with 69.1 cm/s (range 39-125) compared with 96.7 cm/s (range 60-142) for Doppler ultrasound (p < 0.001). Reproducibility of PC-MR was high (p > 0.05).

CONCLUSION

The MR-compatible DUS for fetal cardiac gating allows for PC-MR angiography in the fetal AoD. Comparison with Doppler ultrasound revealed a highly significant correlation of peak velocities with underestimation of PC-MR velocities. This new technique for direct fetal cardiac gating indicates the potential of PC-MR angiography for assessing fetal hemodynamics.

KEY POINTS

• The developed MR-compatible Doppler ultrasound sensor allows direct fetal cardiac gating and can be used for prenatal dynamic cardiovascular MRI. • The MR-compatible Doppler ultrasound sensor was successfully applied to perform intrauterine phase-contrast MR angiography of the fetal aorta, which revealed a highly significant correlation with Doppler ultrasound measurements. • As fetal flow hemodynamics is an important parameter in the diagnosis and management of fetal pathologies, fetal phase-contrast MR angiography may offer an alternative imaging method in addition to Doppler ultrasound and develop as a second line tool in the evaluation of fetal flow hemodynamics.

Doppler measurements of both umbilical arteries do not improve predictive value for adverse perinatal outcomes in small-for-gestational age fetuses

OBJECTIVE

To assess agreement of Doppler ultrasound measurements of the two umbilical arteries in small-for gestational age (SGA) fetuses, and to compare discriminative ability between the two arteries for adverse perinatal outcome.

STUDY DESIGN

We analysed a prospective cohort of singleton SGA pregnancies, in which the pulsatility index (PI) of both umbilical arteries was standardly measured by Doppler ultrasound in the free-floating umbilical cord. The outcome of interest was a composite adverse outcome, defined as perinatal death, Apgar score <7 at 5 min, cesarean section for fetal distress, and neonatal intensive care unit admission.

RESULTS

A total of 531 measurements were performed in 124 patients. Mean absolute difference between PI measured in the two umbilical arteries was 0.14 (95% CI: 0.12 to 0.15), showing good agreement with an ICC of 0.830 (95% CI: 0.801 to 0.854). Perinatal outcomes were available for 101 patients, of which 48 patients (48%) had a composite adverse perinatal outcome. We found no significant differences between AUCs for prediction of an adverse outcome based on lowest, highest and mean PI values in the two umbilical arteries (AUCs = 0.75, 0.74, 0.75 with p = 0.91). As a comparison, the AUC of a PI value obtained in a single, randomly selected umbilical artery was 0.74.

CONCLUSION

The two umbilical arteries show good agreement in terms of their PI values in the free-floating umbilical cord, and do not differ in terms of their discriminative ability for adverse perinatal outcome in SGA fetuses. We found no evidence of an added value of standard Doppler measurement of both umbilical arteries.

Predictive accuracy of cerebroplacental ratio for adverse perinatal and neurodevelopmental outcomes in suspected fetal growth restriction: systematic review and meta-analysis

OBJECTIVE

The cerebroplacental ratio (CPR) has been proposed for the routine surveillance of pregnancies with suspected fetal growth restriction (FGR), but the predictive performance of this test is unclear. The aim of this study was to determine the accuracy of CPR for predicting adverse perinatal and neurodevelopmental outcomes in suspected FGR.

METHODS

PubMed, EMBASE, CINAHL and Lilacs were searched from inception to 31 July 2017 for cohort or cross-sectional studies reporting on the accuracy of CPR for predicting adverse perinatal and/or neurodevelopmental outcomes in singleton pregnancies with FGR suspected antenatally based on sonographic parameters. Summary receiver-operating characteristics (ROC) curves, pooled sensitivities and specificities, and summary likelihood ratios (LRs) were generated.

RESULTS

Twenty-two studies (including 4301 women) met the inclusion criteria. Summary ROC curves showed that the best predictive accuracy of CPR was for perinatal death and the worst was for neonatal acidosis, with areas under the summary ROC curves of 0.83 and 0.57, respectively. The predictive accuracy of CPR was moderate to high for perinatal death (pooled sensitivity and specificity of 93% and 76%, respectively, and summary positive and negative LRs of 3.9 and 0.09, respectively) and low for composite of adverse perinatal outcomes, Cesarean section for non-reassuring fetal status, 5-min Apgar score < 7, admission to the neonatal intensive care unit, neonatal acidosis and neonatal morbidity, with summary positive and negative LRs ranging from 1.1 to 2.5 and 0.3 to 0.9, respectively. An abnormal CPR result had moderate accuracy for predicting small-for-gestational age at birth (summary positive LR of 7.4). CPR had a higher predictive accuracy in pregnancies with suspected early-onset FGR. No study provided data for assessing the predictive accuracy of CPR for adverse neurodevelopmental outcome.

CONCLUSION

CPR appears to be useful in predicting perinatal death in pregnancies with suspected FGR. Nevertheless, before incorporating CPR into the routine clinical management of suspected FGR, randomized controlled trials should assess whether the use of CPR reduces perinatal death or other adverse perinatal outcomes. Copyright © 2018 ISUOG. Published by John Wiley & Sons Ltd.

Fetal myocardial performance index in assessment and management of small-for-gestational-age fetus: a cohort and nested case-control study

OBJECTIVE

To assess the clinical utility of the fetal myocardial performance index (MPI) in assessment and management of the small-for-gestational-age (SGA) fetus/growth-restricted fetus (FGR).

METHODS

This was a prospective cohort study in metropolitan Australia of patients referred in the period June 2012 to March 2015 to fetal medicine services at 24-38 weeks' gestation for suspected singleton SGA/FGR (estimated fetal weight (EFW) < 10^th centile with or without abnormal umbilical artery (UA) Doppler) pregnancy. Patients had MPI assessed in addition to routine measures, and were followed through to birth. We compared MPI values against those of a local reference population and gestational age-matched controls, and assessed the correlation with perinatal outcome and other Doppler measures.

RESULTS

Fifty-two cases were included, 38 diagnosed < 32 weeks and 14 diagnosed ≥ 32 weeks. None demonstrated significantly elevated left, right or delta MPI compared with the reference population or with gestational age-matched controls at the time of first MPI evaluation. There were no consistent longitudinal patterns in MPI that would suggest its clinical utility. The mean ± SD gestational age at delivery was 34.6 ± 3.8 weeks and birth weight was 1.7 ± 0.6 kg, and the median neonatal hospital admission time was 27 days, confirming a pathological cohort. There were no significant correlations between left, right or delta-MPI and perinatal outcome, although there were significant correlations between UA, middle cerebral artery (MCA) and ductus venosus (DV) Doppler and perinatal outcome (birth weight, gestational age at birth and length of neonatal hospital stay). Exploratory subgroup comparisons (EFW < 3^rd vs 3^rd -10^th centile; early- vs late-onset; abnormal vs normal UA Doppler) found only minor differences in MPI, reaching statistical, but not clinical, significance, only in the EFW < 3^rd vs 3^rd -10^th centile comparison.

CONCLUSIONS

MPI did not demonstrate clinical utility in either triage or longitudinal follow-up of an SGA/FGR cohort presenting to fetal medicine services. Given that prior research suggesting its utility originates from single-center cohorts, while multicenter, large cohorts have suggested little utility or no additional utility if routine UA/MCA/DV Doppler is performed, publication bias may have affected previous reports. It seems unlikely that MPI has clinical utility in assessment and management of SGA/FGR fetuses. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Multidisciplinary consensus on screening for, diagnosis and management of fetal growth restriction in the Netherlands

BACKGROUND

Screening for, diagnosis and management of intrauterine growth restriction (IUGR) is often performed in multidisciplinary collaboration. However, variation in screening methods, diagnosis and management of IUGR may lead to confusion. In the Netherlands two monodisciplinary guidelines on IUGR do not fully align. To facilitate effective collaboration between different professionals in perinatal care, we undertook a Delphi study with uniform recommendations as our primary result, focusing on issues that are not aligned or for which specifications are lacking in the current guidelines.

METHODS

We conducted a Delphi study in three rounds. A purposively sampled selection of 56 panellists participated: 27 representing midwife-led care and 29 obstetrician-led care. Consensus was defined as agreement between the professional groups on the same answer and among at least 70% of the panellists within groups.

RESULTS

Per round 51 or 52 (91% - 93%) panellists responded. This has led to consensus on 27 issues, leading to four consensus based recommendations on screening for IUGR in midwife-led care and eight consensus based recommendations on diagnosis and eight on management in obstetrician-led care. The multidisciplinary project group decided on four additional recommendations as no consensus was reached by the panel. No recommendations could be made about induction of labour versus expectant monitoring, nor about the choice for a primary caesarean section.

CONCLUSIONS

We reached consensus on recommendations for care for IUGR within a multidisciplinary panel. These will be implemented in a study on the effectiveness and cost-effectiveness of routine third trimester ultrasound for monitoring fetal growth. Research is needed to evaluate the effects of implementation of these recommendations on perinatal outcomes.

TRIAL REGISTRATION

NTR4367 .

A Low Cerebroplacental Ratio at 20-24 Weeks of Gestation Can Predict Reduced Fetal Size Later in Pregnancy or at Birth

AIM

To determine whether Doppler evaluation at 20-24 weeks of gestation can predict reduced fetal size later in pregnancy or at birth.

METHODS

Fetal biometry and Doppler velocimetry were performed in 2,986 women with a singleton pregnancy at 20-24 weeks of gestation. Predictive performances of the umbilical artery pulsatility index (UA-PI) or the mean uterine artery pulsatility index (UtA-PI) >95th percentile, middle cerebral artery pulsatility index, or cerebroplacental ratio (CPR) <5th percentile for early small for gestational age (SGA; <34 weeks of gestation), late SGA (≥34 weeks of gestation), or SGA at birth (birthweight <10th percentile) were analyzed.

RESULTS

The prevalence of early SGA, late SGA, and SGA at birth was 1.1, 9.6, and 14.7%, respectively. A CPR <5th percentile had a positive likelihood ratio (LR+) of 8.2 (95% confidence interval [CI] 5.7-12.0) for early SGA, a LR+ of 1.6 (95% CI 1.1-1.2) for late SGA, and a LR+ of 1.9 (95% CI 1.4-2.6) for SGA at birth. A UtA-PI >95th percentile was associated with late SGA and SGA at birth, while an UA-PI >95th percentile was associated with early SGA. Associations were higher in fetuses with an estimated fetal weight <10th percentile.

CONCLUSION

Fetal biometry and Doppler evaluation at 20-24 weeks of gestation can predict early and late SGA as well as SGA at birth.

Use of Doppler velocimetry in diagnosis and prognosis of intrauterine growth restriction (IUGR): A Review

Intrauterine growth restriction (IUGR) is a condition which has been difficult to assess at an early stage, resulting in the delivery of children who have poor genetic growth potential. Currently, IUGR classification is based upon the system of ultrasound biometry. Doppler velocimetry allows the measurement of hemodynamic flow of major fetal vessels, comparing the flow indices and patterns of normal and IUGR cases. In this review, the effectiveness of Doppler velocimetry in assessing blood flow in major vessels including the umbilical artery, ductus venosus, and middle cerebral artery was studied for both diagnostic and prognostic screening of IUGR. The umbilical artery is the most frequently studied vessel in Doppler velocimetry due to its accessibility and the strength of its associations with fetal outcomes. Abnormalities in the ductus venosus waveform can be indicative of increased resistance in the right atrium due to placental abnormalities. The middle cerebral artery is the most studied fetal cerebral artery and can detect cerebral blood flow and direction, which is why these three vessels were selected to be examined in this context. A potential mathematical model could be developed to incorporate these Doppler measurements which are indicative of IUGR, in order to reduce perinatal mortality. The purpose of the proposed algorithm is to integrate Doppler velocimetry with biophysical profiling in order to determine the optimal timing of delivery, thus reducing the risks of adverse perinatal outcomes.

Ultrasound detection of altered placental vascular morphology based on hemodynamic pulse wave reflection

Abnormally pulsatile umbilical artery (UA) Doppler ultrasound velocity waveforms are a hallmark of severe or early onset placental-mediated intrauterine growth restriction (IUGR), whereas milder late onset IUGR pregnancies typically have normal UA pulsatility. The diagnostic utility of these waveforms to detect placental pathology is thus limited and hampered by factors outside of the placental circulation, including fetal cardiac output. In view of these limitations, we hypothesized that these Doppler waveforms could be more clearly understood as a reflection phenomenon and that a reflected pulse pressure wave is present in the UA that originates from the placenta and propagates backward along the UA. To investigate this, we developed a new ultrasound approach to isolate that portion of the UA Doppler waveform that arises from a pulse pressure wave propagating backward along the UA. Ultrasound measurements of UA lumen diameter and flow waveforms were used to decompose the observed flow waveform into its forward and reflected components. Evaluation of CD1 and C57BL/6 mice at embryonic day (E)15.5 and E17.5 demonstrated that the reflected waveforms diverged between the strains at E17.5, mirroring known changes in the fractal geometry of fetoplacental arteries at these ages. These experiments demonstrate the feasibility of noninvasively measuring wave reflections that originate from the fetoplacental circulation. The observed reflections were consistent with theoretical predictions based on the area ratio of parent to daughters at bifurcations in fetoplacental arteries suggesting that this approach could be used in the diagnosis of fetoplacental vascular pathology that is prevalent in human IUGR. Given that the proposed measurements represent a subset of those currently used in human fetal surveillance, the adaptation of this technology could extend the diagnostic utility of Doppler ultrasound in the detection of placental vascular pathologies that cause IUGR.NEW & NOTEWORTHY Here, we describe a novel approach to noninvasively detect microvascular changes in the fetoplacental circulation using ultrasound. The technique is based on detecting reflection pulse pressure waves that travel along the umbilical artery. Using a proof-of-principle study, we demonstrate the feasibility of the technique in two strains of experimental mice.

The use of angiogenic biomarkers in maternal blood to identify which SGA fetuses will require a preterm delivery and mothers who will develop pre-eclampsia

OBJECTIVE

To determine (1) whether maternal plasma concentrations of angiogenic and anti-angiogenic factors can predict which mothers diagnosed with "suspected small for gestational age fetuses (sSGA)" will develop pre-eclampsia (PE) or require an indicated early preterm delivery (≤ 34 weeks of gestation); and (2) whether risk assessment performance is improved using these proteins in addition to clinical factors and Doppler parameters.

METHODS

This prospective cohort study included women with singleton pregnancies diagnosed with sSGA (estimated fetal weight <10th percentile) between 24 and 34 weeks of gestation (n = 314). Plasma concentrations of soluble vascular endothelial growth factor receptor-1 (sVEGFR-1), soluble endoglin (sEng) and placental growth factor (PlGF) were determined in maternal blood obtained at the time of diagnosis. Doppler velocimetry of the umbilical (Umb) and uterine (UT) arteries was performed. The outcomes were (1) subsequent development of PE; and (2) indicated preterm delivery at ≤ 34 weeks of gestation (excluding deliveries as a result of spontaneous preterm labor, preterm pre-labor rupture of membranes or chorioamnionitis).

RESULTS

(1) The prevalence of PE and indicated preterm delivery was 9.2% (n = 29/314) and 7.3% (n = 23/314), respectively; (2) the area under the receiver operating characteristic curve (AUC) for the identification of patients who developed PE and/or required indicated preterm delivery was greater than 80% for the UT artery pulsatility index (PI) z-score and each biochemical marker (including their ratios) except sVEGFR-1 MoM; (3) using cutoffs at a false positive rate of 15%, women with abnormal plasma concentrations of angiogenic/anti-angiogenic factors were 7-13 times more likely to develop PE, and 12-22 times more likely to require preterm delivery than those with normal plasma MoM concentrations of these factors; (4) sEng, PlGF, PIGF/sEng and PIGF/sVEGFR-1 ratios MoM, each contributed significant information about the risk of PE beyond that provided by clinical factors and/or Doppler parameters: women who had low MoM values for these biomarkers were at 5-9 times greater risk of developing PE than women who had normal values, adjusting for clinical factors and Doppler parameters (adjusted odds ratio for PlGF: 9.1, PlGF/sEng: 5.6); (5) the concentrations of sVEGFR-1 and PlGF/sVEGFR-1 ratio MoM, each contributed significant information about the risk of indicated preterm delivery beyond that provided by clinical factors and/or Doppler parameters: women who had abnormal values were at 8-9 times greater risk for indicated preterm delivery, adjusting for clinical factors and Doppler parameters; and (6) for a two-stage risk assessment (Umb artery Doppler followed by Ut artery Doppler plus biochemical markers), among women who had normal Umb artery Doppler velocimetry (n = 279), 21 (7.5%) developed PE and 11 (52%) of these women were identified by an abnormal UT artery Doppler mean PI z-score (>2SD): a combination of PlGF/sEng ratio MoM concentration and abnormal UT artery Doppler velocimetry increased the sensitivity of abnormal UT artery Doppler velocimetry to 76% (16/21) at a fixed false-positive rate of 10% (p = 0.06).

CONCLUSION

Angiogenic and anti-angiogenic factors measured in maternal blood between 24 and 34 weeks of gestation can identify the majority of mothers diagnosed with "suspected SGA" who subsequently developed PE or those who later required preterm delivery ≤ 34 weeks of gestation. Moreover, incorporation of these biochemical markers significantly improves risk assessment performance for these outcomes beyond that of clinical factors and uterine and umbilical artery Doppler velocimetry.

Associations of maternal personal exposure to air pollution on fetal weight and fetoplacental Doppler: A prospective cohort study

We determined the influence of maternal air pollution exposure during each trimester of pregnancy on fetal and birth weight and fetoplacental hemodynamics. In total, 366 women with singleton pregnancies were prospectively followed in the city of São Paulo, Brazil. Nitrogen dioxide (NO2) and ozone (O3) were measured during each trimester using passive personal samplers. We evaluated fetal weight and Doppler velocimetry data from the umbilical, middle cerebral, and uterine arteries in the 3rd trimester, and birth weight. Multivariate analysis was performed, controlling for known determinants of fetal weight. Exposure to higher levels of O3 during the 2nd trimester was associated with higher umbilical artery pulsatility indices (PIs) [p=0.013; beta=0.017: standard error (SE)=0.007]. Exposure to higher levels of O3 during the 3rd trimester was associated with lower umbilical artery PIs (p=0.011; beta=-0.021; SE=0.008). Our results suggest that in the environment of São Paulo, O3 may affects placental vascular resistance.

Diagnosis and Treatment of Hypertensive Pregnancy Disorders. Guideline of DGGG (S1-Level, AWMF Registry No. 015/018, December 2013)

Purpose: Official guideline published and coordinated by the German Society of Gynecology and Obstetrics (DGGG). Hypertensive pregnancy disorders contribute significantly to perinatal as well as maternal morbidity and mortality worldwide. Also in Germany these diseases are a major course for hospitalization during pregnancy, iatrogenic preterm birth and long-term cardiovascular morbidity. Methods: This S1-guideline is the work of an interdisciplinary group of experts from a range of different professions who were commissioned by DGGG to carry out a systematic literature search of positioning injuries. Members of the participating scientific societies develop a consensus in an informal procedure. Afterwards the directorate of the scientific society approves the consensus. Recommendations: This guideline summarizes the state-of-art for classification, risk stratification, diagnostic, treatment of hypertensive pregnancy disorders.

The role of preterm placental calcification on assessing risks of stillbirth

INTRODUCTION

Stillbirth is an important issue in antenatal care and much remains unknown. This cohort study aims to explore the previously un-identified risk factor of third-trimester stillbirth to determine if Grade III preterm placental calcification (PPC) is associated with stillbirth.

METHODS

At a tertiary teaching hospital, obstetric ultrasonography was performed at 28 weeks' gestation to establish a diagnosis of PPC. Pregnancies with multifetal gestations, major fetal congenital anomalies, termination, cord accidents, apparent intrauterine infection, and antepartum complications were excluded.

RESULTS

15,122 eligible pregnancies were categorized as stillbirth (n = 99) and livebirth (n = 15,023) groups. Between these two groups, there were no significant differences in maternal age, BMI, and parity, but significant differences in smoking and in PPC (35.4% vs 6.3%, p < 0.001) were observed. The peak occurrence of stillbirths was at 30 and 37 weeks' gestation, with a bimodal distribution of 11 and 17 stillbirths, respectively. For pregnancies with or without PPC, the incidences of stillbirths per-1000-births were 35.9 and 4.5, respectively. Using Kaplan-Meier survival analysis, at 40 weeks' gestation the cumulative stillbirth risk for pregnancies with PPC was higher compared to those without PPC. Logistic regression revealed that after adjusting for the effects of smoking and demographic factors, the risk of stillbirth (adjusted OR:7.62; 95% CI:5.00-11.62) was much higher when PPC was present.

DISCUSSION

Grade III PPC is associated with a higher incidence of stillbirth, and identified an independent risk factor. Being a pathologic implication, it may precede this negative outcome and can serve as a warning sign or marker when noted on ultrasonography.

Antenatal tests of fetal wellbeing

In current obstetric practice, there is frequently a need to assess fetal wellbeing. This is particularly so in those fetuses at risk, including the small-for-gestational-age fetus or the fetus of a mother who presents with reduced fetal movements or who has an obstetric complication such as pre-eclampsia. It is important that the clinician is able to assess fetal wellbeing in such cases, especially in preterm gestations, when inappropriate delivery could have serious adverse consequences. In this paper, we review the current evidence for the use and the limitations of widely used methods of antenatal monitoring including the use of cardiotocography, biophysical profile, and ultrasound-derived parameters including umbilical artery, middle cerebral artery, and ductus venosus Doppler flow.

IFPA Gábor Than Award Lecture: Recognition of placental failure is key to saving babies' lives

In high-income countries, placental failure is implicated in up to 65% of cases of stillbirth. Placental failure describes the situation where the placenta cannot meet the fetus' needs and may be the end-result of a variety of underlying pathological processes evident in the placental disc, membranes and umbilical cord. These include lesions with genetic, environmental, infectious, inflammatory, mechanical, metabolic, traumatic or vascular origin. Investigation of placental tissue from stillbirths and from pregnancies at an increased risk of stillbirth has demonstrated changes in macroscopic and microscopic structure which are themselves related to abnormal placental function. A better understanding and identification of placental failure may improve the management of pregnancy complications and of pregnancies after stillbirth (which have a 5-fold increased risk of stillbirth). The majority of current antenatal tests focus on the fetus and its response to the intrauterine environment; few of these investigations reduce stillbirths in low-risk pregnancies. However, some currently used investigations reflect placental development, structure and vascular function, while other investigations employed in clinical research settings such as the evaluation of placental structure and shape have a good predictive value for adverse fetal outcome. In addition, recent studies suggest that biomarkers of placental inflammation and deteriorating placental function can be detected in maternal blood suggesting that holistic evaluation of placental structure and function is possible. We anticipate that development of reliable tests of placental structure and function, coupled to assessment of fetal wellbeing offer a new opportunity to identify pregnancies at risk of stillbirth and to direct novel therapeutic strategies to prevent it.

Fetal middle cerebral artery and umbilical artery pulsatility index: effects of maternal characteristics and medical history

OBJECTIVE

To define the contribution of maternal variables which influence the measured fetal middle cerebral artery (MCA) and umbilical artery (UA) pulsatility index (PI) in the assessment of fetal wellbeing.

METHODS

Maternal characteristics and medical history were recorded and fetal MCA-PI and UA-PI (n = 36,818) were measured in women with singleton pregnancies attending a routine hospital visit at 30 + 0 to 37 + 6 weeks' gestation. For pregnancies delivering phenotypically normal live births or stillbirths ≥ 30 weeks' gestation, variables among maternal demographic characteristics and medical history that are important in the prediction of MCA-PI and UA-PI were determined by multiple linear regression analysis.

RESULTS

Significant independent contributions to MCA-PI were provided by gestational age at assessment, East Asian racial origin, being parous and birth-weight Z-score of the neonate of the previous pregnancy. Significant independent contributions to UA-PI were provided by gestational age at assessment, Afro-Caribbean, East Asian and mixed racial origin, cigarette smoking, being parous and birth-weight Z-score of the neonate of the previous pregnancy. Multiple linear regression analysis was used to define the contribution of maternal variables that influence the measured MCA-PI and UA-PI and express the values as multiples of the median (MoMs). The cerebroplacental ratio (CPR) MoM was calculated by dividing MCA-PI MoM by UA-PI MoM. The model was shown to provide an adequate fit of MoM values for all covariates, both in pregnancies that delivered small-for-gestational-age neonates and in those without this pregnancy complication.

CONCLUSIONS

A model was fitted to express MCA-PI, UA-PI and CPR as MoMs after adjusting for variables from maternal characteristics and medical history that affect this measurement.

Is quality and completeness of reporting of systematic reviews and meta-analyses published in high impact radiology journals associated with citation rates?

Purpose

The purpose of this study is to determine whether study quality and completeness of reporting of systematic reviews (SR) and meta-analyses (MA) published in high impact factor (IF) radiology journals is associated with citation rates.

Methods

All SR and MA published in English between Jan 2007–Dec 2011, in radiology journals with an IF >2.75, were identified on Ovid MEDLINE. The Assessing the Methodologic Quality of Systematic Reviews (AMSTAR) checklist for study quality, and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist for study completeness, was applied to each SR & MA. Each SR & MA was then searched in Google Scholar to yield a citation rate. Spearman correlation coefficients were used to assess the relationship between AMSTAR and PRISMA results with citation rate. Multivariate analyses were performed to account for the effect of journal IF and journal 5-year IF on correlation with citation rate. Values were reported as medians with interquartile range (IQR) provided.

Results

129 studies from 11 journals were included (50 SR and 79 MA). Median AMSTAR result was 8.0/11 (IQR: 5–9) and median PRISMA result was 23.0/27 (IQR: 21–25). The median citation rate for SR & MA was 0.73 citations/month post-publication (IQR: 0.40–1.17). There was a positive correlation between both AMSTAR and PRISMA results and SR & MA citation rate; ρ=0.323 (P=0.0002) and ρ=0.327 (P=0.0002) respectively. Positive correlation persisted for AMSTAR and PRISMA results after journal IF was partialed out; ρ=0.243 (P=0.006) and ρ=0.256 (P=0.004), and after journal 5-year IF was partialed out; ρ=0.235 (P=0.008) and ρ=0.243 (P=0.006) respectively.

Conclusion

There is a positive correlation between the quality and the completeness of a reported SR or MA with citation rate which persists when adjusted for journal IF and journal 5-year IF.

UNDERSTANDING THE PLACENTAL AETIOLOGY OF FETAL GROWTH RESTRICTION; COULD THIS LEAD TO PERSONALIZED MANAGEMENT STRATEGIES?

Fetal growth restriction (FGR) is defined as the failure of a fetus to attain its full genetic growth potential. It is a leading cause of stillbirth, prematurity, cerebral palsy and perinatal mortality. Small size at birth increases surviving infants’ lifelong risk of adverse health outcomes associated with the metabolic syndrome. The pathophysiology of abnormal fetal growth is extremely complex and incompletely understood, with a plethora of genetic, signalling and metabolic candidates under investigation, many of which may result in abnormal structure and function of the placenta. In contrast to, or maybe because of, the underlying complexities of FGR, the strategies clinicians have for identifying and managing this outcome are conspicuously limited. Current clinical practice is restricted to identifying pregnancies at risk of FGR, and when FGR is detected, using intensive monitoring to guide the timing of delivery to optimise fetal outcomes. Abnormal Doppler indices in the umbilical artery are strongly associated with poor perinatal outcomes and are currently the “gold standard” for clinical surveillance of the growth-restricted fetus.

The challenge of pregnancy for patients with SLE

Pregnancy poses an important challenge for doctors looking after women with systemic lupus erythematosus. Knowledge about safety of medications, the effect of pregnancy on such disease, and vice versa, together with multidisciplinary team care, are basic cornerstones needed to provide the best obstetric and medical care to these women. Pre-conceptional counselling constitutes the ideal scenario where a patient's previous obstetric history, organ damage, disease activity, serological profile and additional medical history can be summarized. Important issues regarding medication adjustment, planned scans and visits, and main risks discussion should also be raised at this stage. Planned pregnancies lead to better outcomes for both mothers and babies. Close surveillance throughout pregnancy and the puerperium, and tailored management approach guarantee the highest rates of successful pregnancies in these women.

Brain sparing in fetal mice: BOLD MRI and Doppler ultrasound show blood redistribution during hypoxia

Mice reproduce many features of human pregnancy and have been widely used to model disorders of pregnancy. However, it has not been known whether fetal mice reproduce the physiologic response to hypoxia known as brain sparing, where blood flow is redistributed to preserve oxygenation of the brain at the expense of other fetal organs. In the present study, blood oxygen level-dependent (BOLD) magnetic resonance imaging (MRI) and Doppler ultrasound were used to determine the effect of acute hypoxia on the fetal blood flow in healthy, pregnant mice. As the maternal inspired gas mixture was varied between 100% and 8% oxygen on the timescale of minutes, the BOLD signal intensity decreased by 44±18% in the fetal liver and by 12±7% in the fetal brain. Using Doppler ultrasound measurements, mean cerebral blood velocity was observed to rise by 15±8% under hypoxic conditions relative to hyperoxia. These findings are consistent with active regulation of cerebral oxygenation and clearly show brain sparing in fetal mice.

Added value of umbilical vein flow as a predictor of perinatal outcome in term small-for-gestational-age fetuses

OBJECTIVE

To compare umbilical vein (UV) flow with standard Doppler parameters in prediction of adverse perinatal outcome in late-onset small-for-gestational age (SGA) fetuses.

METHODS

Umbilical, uterine and middle cerebral arteries, and UV blood flow were evaluated by Doppler before delivery in a cohort of 193 term SGA fetuses. The value of the Doppler parameters to predict risk of emergency delivery for non-reassuring fetal status and neonatal metabolic acidosis was analyzed.

RESULTS

Fifty-three (27%) fetuses had non-reassuring fetal status requiring emergency delivery, whereas 21 (11%) newborns developed neonatal metabolic acidosis. Multivariable analysis showed that significant contributions to prediction of emergency delivery for non-reassuring fetal status and neonatal metabolic acidosis were provided by middle cerebral artery (MCA) pulsatility index (PI) and UV blood flow normalized by fetal weight. Decision tree analysis defined three groups with increasing risk of need for emergency delivery for non-reassuring fetal status: MCA-PI > 1.46 (risk 15.6%); MCA-PI ≤ 1.46 and UV blood flow > 68 mL/min/kg (risk 25%); and MCA-PI ≤ 1.46 and UV flow ≤ 68 mL/min/kg (risk 53.1%); and two groups with different risks of neonatal metabolic acidosis: UV flow > 68 mL/min/kg or UV flow ≤ 68 mL/min/kg and MCA-PI > 1.23 (risk ≤ 10%); and UV flow ≤ 68 mL/min/kg and MCA-PI ≤ 1.23 (risk 39.1%).

CONCLUSION

The evaluation of UV blood flow with spectral brain Doppler allows better identification of SGA fetuses with late-onset intrauterine growth restriction at risk of adverse perinatal outcome.