Added value of cerebro-placental ratio and uterine artery Doppler at routine third trimester screening as a predictor of SGA and FGR in non-selected pregnancies

Diagnostic performance of 32 vs 36 weeks ultrasound in predicting late-onset fetal growth restriction and small-for-gestational-age neonates: a systematic review and meta-analysis

OBJECTIVE

Fetal growth restriction is an independent risk factor for fetal death and adverse neonatal outcomes. The main aim of this study was to investigate the diagnostic performance of 32 vs 36 weeks ultrasound of fetal biometry in detecting late-onset fetal growth restriction and predicting small-for-gestational-age neonates.

DATA SOURCES

A systematic search was performed to identify relevant studies published until June 2022, using the databases PubMed, Web of Science, and Scopus.

STUDY ELIGIBILITY CRITERIA

Cohort studies in low-risk or unselected singleton pregnancies with screening ultrasound performed at ≥32 weeks of gestation were used.

METHODS

The estimated fetal weight and abdominal circumference were assessed as index tests for the prediction of small for gestational age (birthweight of <10th percentile) and detecting fetal growth restriction (estimated fetal weight of <10th percentile and/or abdominal circumference of <10th percentile). The quality of the included studies was independently assessed by 2 reviewers using the Quality Assessment of Diagnostic Accuracy Studies 2 tool. For the meta-analysis, hierarchical summary area under the receiver operating characteristic curves were constructed, and quantitative data synthesis was performed using random-effects models.

RESULTS

The analysis included 25 studies encompassing 73,981 low-risk pregnancies undergoing third-trimester ultrasound assessment for growth, of which 5380 neonates (7.3%) were small for gestational age at birth. The pooled sensitivities for estimated fetal weight of <10th percentile and abdominal circumference of <10th percentile in predicting small for gestational age were 36% (95% confidence interval, 27%-46%) and 37% (95% confidence interval, 19%-60%), respectively, at 32 weeks ultrasound and 48% (95% confidence interval, 41%-56%) and 50% (95% confidence interval, 25%-74%), respectively, at 36 weeks ultrasound. The pooled specificities for estimated fetal weight of <10th percentile and abdominal circumference of <10th percentile in detecting small for gestational age were 93% (95% confidence interval, 91%-95%) and 95% (95% confidence interval, 85%-98%), respectively, at 32 weeks ultrasound and 93% (95% confidence interval, 91%-95%) and 97% (95% confidence interval, 85%-98%), respectively, at 36 weeks ultrasound. The observed diagnostic odds ratios for an estimated fetal weight of <10th percentile and an abdominal circumference of <10th percentile in detecting small for gestational age were 8.8 (95% confidence interval, 5.4-14.4) and 11.6 (95% confidence interval, 6.2-21.6), respectively, at 32 weeks ultrasound and 13.3 (95% confidence interval, 10.4-16.9) and 36.0 (95% confidence interval, 4.9-260.0), respectively, at 36 weeks ultrasound. The pooled sensitivity, specificity, and diagnostic odds ratio in predicting fetal growth restriction were 71% (95% confidence interval, 52%-85%), 90% (95% confidence interval, 79%-95%), and 25.8 (95% confidence interval, 14.5-45.8), respectively, at 32 weeks ultrasound and 48% (95% confidence interval, 41%-55%), 94% (95% confidence interval, 93%-96%), and 16.9 (95% confidence interval, 10.8-26.6), respectively, at 36 weeks ultrasound. Abdominal circumference of <10th percentile seemed to have comparable sensitivity to estimated fetal weight of <10th percentile in predicting small-for-gestational-age neonates.

CONCLUSION

An ultrasound assessment of the fetal biometry at 36 weeks of gestation seemed to have better predictive accuracy for small-for-gestational-age neonates than an ultrasound assessment at 32 weeks of gestation. However, an opposite trend was noted when the outcome was fetal growth restriction. Fetal abdominal circumference had a similar predictive accuracy to that of estimated fetal weight in detecting small-for-gestational-age neonates.

Efficiency of the Cerebroplacental Ratio in Identifying High-Risk Late-Term Pregnancies

Background and Objectives: Over the last few years, great interest has arisen in the role of the cerebroplacental ratio (CPR) to identify low-risk pregnancies at higher risk of adverse pregnancy outcomes. This study aimed to assess the predictive capacity of the CPR for adverse perinatal outcomes in all uncomplicated singleton pregnancies attending an appointment at 40-42 weeks. Materials and Methods: This is a retrospective cohort study including all consecutive singleton pregnancies undergoing a routine prenatal care appointment after 40 weeks in three maternity units in Spain and the United Kingdom from January 2017 to December 2019. The primary outcome was adverse perinatal outcomes defined as stillbirth or neonatal death, cesarean section or instrumental delivery due to fetal distress during labor, umbilical arterial cord blood pH < 7.0, umbilical venous cord blood pH < 7.1, Apgar score at 5 min < 7, and admission to the neonatal unit. Logistic mixed models and ROC curve analyses were used to analyze the data. Results: A total of 3143 pregnancies were analyzed, including 537 (17.1%) with an adverse perinatal outcome. Maternal age (odds ratio (OR) 1.03, 95% confidence interval (CI) 1.01 to 1.04), body mass index (OR 1.04, 95% CI 1.03 to 1.06), racial origin (OR 2.80, 95% CI 1.90 to 4.12), parity (OR 0.36, 95% CI 0.29 to 0.45), and labor induction (OR 1.79, 95% CI 1.36 to 2.35) were significant predictors of adverse perinatal outcomes with an area under the ROC curve of 0.743 (95% CI 0.720 to 0.766). The addition of the CPR to the previous model did not improve performance. Additionally, the CPR alone achieved a detection rate of only 11.9% (95% CI 9.3 to 15) when using the 10th centile as the screen-positive cutoff. Conclusions: Our data on late-term unselected pregnancies suggest that the CPR is a poor predictor of adverse perinatal outcomes.

Association between transabdominal uterine artery Doppler and small-for-gestational-age: a systematic review and meta-analysis

BACKGROUND

The association between uterine artery Doppler (UtA) measurements and small for gestational age (SGA) has not been quantitatively analyzed throughout the whole pregnancy. This systematic review and meta-analysis aims to comprehensively explore the association between UtA measurements and SGA in the first, second, and third trimesters.

METHODS

Studies were searched from Pubmed, Embase, Cochrane Library, and Web of Science. Weighted mean difference (WMD), odds ratio (OR), and relative risk (RR) with 95% confidence interval (CI) were used as the effect size. Heterogeneity of all effect sizes was tested and quantified using I2 statistics. Sensitivity analysis was conducted for all outcomes, and publication bias was evaluated using Begg's test.

RESULTS

A total of 41 studies were finally included in our meta-analysis. In the first trimester, mean PI was significantly higher in the SGA group than the non-SGA group (WMD: 0.31, 95%CI: 0.19-0.44). In the second trimester, odds of notch presence (OR: 2.54, 95%CI: 2.10-3.08), mean PI (WMD: 0.21, 95%CI: 0.12-0.30), and mean RI (WMD: 0.05, 95%CI: 0.05-0.06) were higher in the SGA group. Also, abnormal UtA measurements were associated with the increased odds of SGA (all P < 0.05). In the third trimester, PI z-score (WMD: 0.62, 95%CI: 0.33-0.91) and PI MoM (WMD: 0.08, 95%CI: 0.06-0.09) showed a significant increase in the SGA group. The odds of SGA were higher in the women with mean PI > 95% (OR: 6.03, 95%CI: 3.24-11.24).

CONCLUSIONS

Abnormal UtA measurements were associated with high odds of SGA, suggesting that UtA might be an adjunctive screening method for SGA in the whole pregnancy.

Perinatal Outcome and its Prediction Using Longitudinal Feto-Maternal Doppler Follow-Up in Late Onset Small for Gestational Age Fetuses - A Prospective Cohort Study

PURPOSE

 To describe the perinatal outcome of a prospective cohort of late-onset small-for-gestational-age (SGA) fetuses and to test adverse perinatal outcome (APO) prediction using Doppler measurements.

METHODS

 Singleton pregnancies from 32 weeks with suspicion of SGA (followed-up each 2 weeks) and randomly selected healthy controls at a university hospital were included. The whole SGA group was divided into the FGR subgroup or SGA percentile 3-10 subgroup. The following Doppler measurements were evaluated prospectively: umbilical artery (UA) pulsatility index (PI), middle cerebral artery (MCA) PI, cerebro-placental ratio (CPR), and mean uterine artery (mUtA) PI. APO was defined as arterial cord blood pH ≤ 7.15 and/or 5-minute Apgar ≤ 7 and/or emergency operative delivery and/or admission to the neonatal unit. Induction of labor was indicated according to a stage-based protocol.

RESULTS

 A total of 149 SGA and 143 control fetuses were included. The number of operative deliveries was similar between both groups (control: 29 %, SGA: 28 %), especially the cesarean delivery rate after the onset of labor (11 % vs. 10 %). Most SGA cases ended up in induction of labor (61 % vs. 31 %, p < 0.001). The areas under the curve (AUC) for APO prediction were similar using the last UA PI, MCA PI, CPR, and mUtA PI and barely reached 0.60. The AUC was best for the FGR subgroup, using the minimal CPR or maximum mUtA PI z-score of all longitudinal measurements (AUC = 0.63).

CONCLUSION

 SGA fetuses do not have a higher rate of operative delivery if managed according to a risk stratification protocol. Prediction of APO is best for SGA and FGR using the "worst" CPR or mUtA PI but it remains moderate.

Middle cerebral artery to uterine artery pulsatility index ratios in pregnancy with fetal growth restriction regarding negative perinatal outcomes

Background/Aim: Fetal growth restriction (FGR) causes a high risk of perinatal morbidity and mortality, and the timing of the correct delivery time decision remains controversial. Cerebroplacental ratio (CPR), umbilical artery, uterine artery (UA) and middle cerebral artery (MCA) Doppler studies are used to predict adverse perinatal outcomes in FGR. However, since there is insufficient reliability for each separately and together, the search for new methods continues. This retrospective study was conducted to determine the degree of neonatal morbidity in fetuses suspected of having FGR by evaluating the MCA to UA pulsatility index (PI) ratios together with frequently used Doppler examinations. Methods: This was a retrospective cohort study conducted in a single-center hospital with the approval of the Medical Institutional Ethics Committee. A total of 424 pregnant women admitted to a tertiary hospital and diagnosed with FGR between July 2020 and December 2021 who were informed and approved were included in the study. Gestational age was confirmed by first trimester sonographic measurements of pregnancy. All pregnant women were examined by Doppler USG and umbilical artery, mean UA, fetal MCA, ductus venosus, CPR (MCA/umbilical artery pulsatility index ratio) and cerebrouterine ratio (MCA/UA) PI values were measured. Negative perinatal outcomes were recorded as blood gas level of the newborn at 7.2 and below, Apgar score of 7 and below at the fifth minute, and needing neonatal intensive care (NICU). Adverse perinatal and postnatal outcomes were recorded and compared with Doppler findings. If there were no signs of a negative perinatal outcome, it was considered a positive outcome. If at least one of the symptoms of adverse perinatal outcomes was present, it was considered a negative outcome Results: Decreased CPR and decreased MCA to UA PI were significantly and positively associated with an increased likelihood of exhibiting negative perinatal outcomes in pregnancies with FGR (P < 0.001, P < 0.001, respectively). The receiver operating characteristic (ROC) curve analysis showed that the optimal cut-off value for MCA to uterine artery PI was 1.41 to predict FGR with 57.37% sensitivity and 62.50% specificity (AUC: 0.629; 95% CI: 0.581–0.675). When the CPR cut-off value was taken as 1.2069, the sensitivity was 42.86% and the specificity 83.93% in predicting negative perinatal outcomes in CPR values below this value (P < 0.001). Conclusion: CPR is the most successful criterion in distinguishing between positive and negative perinatal outcomes. It has been demonstrated that the MCA to uterine artery PI ratio values after CPR can also be used for this distinction. MCA to UA PI ratio sensitivity was higher than CPR and umbilical artery. This situation shows that MCA to uterine artery PI ratio (alone or when evaluated together with PPV and NPV ratios) is a criterion that can be added to other Doppler examinations in predicting negative perinatal outcomes.

Severe smallness as predictor of adverse perinatal outcome in suspected late small-for-gestational-age fetuses: systematic review and meta-analysis

OBJECTIVE

To investigate the performance of severe smallness in the prediction of adverse perinatal outcome among fetuses with suspected late-onset small-for-gestational age (SGA).

METHODS

A systematic search was performed to identify relevant studies in PubMed, Web of Science and Scopus. Late-onset SGA was defined as estimated fetal weight (EFW) or abdominal circumference (AC) < 10^th percentile diagnosed at or after 32 weeks' gestation, while severe SGA was defined as EFW or AC < 3^rd percentile or < 2 SD. Random-effects modeling was used to generate hierarchical summary receiver-operating-characteristics (HSROC) curves. The performance of severe SGA (as a presumptive diagnosis) in predicting adverse perinatal outcome among singleton pregnancies with suspected late-onset SGA was expressed as area under the HSROC curve (AUC), sensitivity, specificity and positive/negative likelihood ratios. The association between suspected severe SGA and adverse perinatal outcome was also assessed by random-effects modeling using the Mantel-Haenszel method and presented as odds ratio (OR). The non-exposed group was defined as non-severe SGA (EFW ≥ 3^rd centile).

RESULTS

Twelve cohort studies were included in this systematic review and meta-analysis. The studies included a total of 3639 fetuses with suspected late-onset SGA, of which 1246 had suspected severe SGA. Significant associations were found between suspected severe SGA and composite adverse perinatal outcome (OR, 1.97 (95% CI, 1.33-2.92)), neonatal intensive care unit admission (OR, 2.87 (95% CI, 1.84-4.47)) and perinatal death (OR, 4.26 (95% CI, 1.07-16.93)). However, summary ROC curves showed limited performance of suspected severe SGA in predicting perinatal outcomes, with AUCs of 60.9%, 66.9%, 53.6%, 57.2%, 54.6% and 64.9% for composite adverse perinatal outcome, neonatal intensive care unit admission, neonatal acidosis, Cesarean section for intrapartum fetal compromise, low Apgar score and perinatal death, respectively.

CONCLUSION

Although suspected severe SGA was associated with a higher risk of perinatal complications, it performed poorly as a standalone parameter in predicting adverse perinatal outcome. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Prenatal prediction of very late onset small-for-gestational age newborns in low-risk pregnancies

OBJECTIVE

To find a multivariate model for predicting small-for-gestational age newborns at 36 weeks' gestation by using clinical, biochemical and ultrasound measurements.

MATERIALS AND METHODS

We evaluated 564 low-risk pregnant women and recorded maternal age, maternal body mass index, maternal mean blood pressure, soluble fms-like tyrosine kinase-1 (multiples of the median), placental growth factor (multiples of the median), soluble fms-like tyrosine kinase-1/placental growth factor ratio, estimated fetal weight centile and mean uterine artery pulsatility index at 36 weeks. Binary logistic regression was used. Statistical significance was set at 95% level (p < 0.05).

RESULTS

We found three multivariate models showing relatively small differences in predictive capability. Model 1 only included estimated fetal weight centiles (area under the curve [AUC] 0.86; R2 = 0.42; p < 0.0001), Model 2 estimated fetal weight centiles and placental growth factor (multiples of the median) (AUC 0.87; R2 = 0.44; p < 0.0001) and Model 3 estimated fetal weight centiles, placental growth factor (multiples of the median) and mean uterine artery pulsatility index (AUC 0.88; R2 = 0.45; p < 0.0001).

CONCLUSION

Small-for-gestational age at delivery may be predicted by using a multivariate formula. The inclusion of parameters other than estimated fetal weight centile at 36 weeks' gestation modestly improves the predictive capability of the model. Clinical decisions should consider whether or not these slight differences deserve a change in current strategies.

The utility of foetal splenic artery Doppler measurement in the diagnosis of late-onset foetal growth restriction

We aimed to examine the contribution of splenic artery (SA) Doppler parameters in the detection of foetuses with late-onset foetal growth restriction (LO-FGR) and to evaluate its power in predicting adverse perinatal outcomes. Within the study's scope, 52 cases in the LO-FGR group and 92 cases in the control group were evaluated. The criteria determined in the Delphi procedure by an international consensus were used to define the LO-FGR. Middle cerebral artery (MCA) pulsatility index (PI) and SA PI were significantly lower in the LO-FGR group (p: .002, p<.001, respectively). Likewise, cerebroplacental ratio (CPR) was significantly lower in the LO-FGR group (p<.001). Decreased CPR and decreased SA PI were significantly and positively associated with an increased likelihood of exhibiting adverse obstetric outcome (p<.001, p: .012, respectively). The receiver operating characteristic (ROC) curve analysis showed that the optimal cut-off value for SA PI was 1.41 to predict LO-FGR with 70.7% sensitivity and 61.5% specificity (AUC = 0.684; 95% CI, 0.594-0.774).Impact StatementWhat is already known on this subject? The main clinical difficulty in late-onset foetal growth restriction (LO-FGR) is the detection of the disease.What do the results of this study add? The splenic artery (SA) pulsatility index (PI) may contribute to both diagnostic and the prediction of adverse perinatal outcomes in LO-FGR cases. Our results showed that the SA PI value, as well as cerebroplacental ratio (CPR), can be a useful parameter in predicting negative outcomes.What are the implications of these findings for clinical practice and/or further research? Various degrees of uteroplacental insufficiency in foetuses with LO-FGR may be associated with abnormalities in SA Doppler velocimetry. Splenic artery Doppler velocimetry can be used for the clinical management of LO-FGR.

Pre- and postnatal brain hemodynamics in pregnancies at term: correlation with Doppler ultrasound, birthweight, and adverse perinatal outcome

PURPOSE

To elucidate the correlation between pre- and postnatal cerebral Doppler in pregnancies close to term and to explore whether they are associated with perinatal outcome.

MATERIALS AND METHODS

Prospective study on singleton pregnancies at 36-37 weeks of gestation. The primary outcome was a composite score of perinatal morbidity, while secondary outcomes were adverse intra-partum outcome and abnormal acid-base status. All pregnancies underwent ultrasound assessment of umbilical artery (UA), middle cerebral artery (MCA), uterine arteries (UtAs) pulsatility index (PI), and cerebroplacental ratio (CPR). At birth, neonatal MCA PI was measured 72 h from delivery and correlated with prenatal Doppler, primary and secondary outcomes. Fisher's test and multivariate logistic regression analysis were used to analyze the data.

RESULTS

One hundred and sixty-six fetuses with both pre- and postnatal Doppler assessment of the MCA were included in the study. The risk of composite perinatal morbidity was higher in fetuses (OR: 5.7, 95% CI 2.2-14.6) and newborns (OR: 4.1, 95% CI 1.8-9.6) with fetal MCA PI < 10th centile. Likewise, the incidence of abnormal acid-base status was higher both in fetuses (20 versus 4.2%, p = .026) and newborns (17.1 versus 3.2%, p = .001) with a low MCA PI before and at birth, respectively. At logistic regression analysis, fetal and neonatal MCAPI were independently associated with composite perinatal morbidity and abnormal acid-base status, but not with adverse intra-partum outcome. In small for gestational age (SGA) fetuses, the incidence of composite perinatal morbidity was higher in fetuses and new-borns presenting compared to those not presenting with an MCA PI < 10th centile (61.5 versus 20%, p = .003 and 52.6% versus 7.1%, p = .008, respectively), while such association was lost when considering non-SGA fetuses.

CONCLUSION

A low MCA PI is associated with adverse perinatal outcome in pregnancies at term and tends to persist after birth.

Routine third-trimester ultrasound for the detection of small-for-gestational age in low-risk pregnancies (ROTTUS study): randomized controlled trial

OBJECTIVE

To compare the proportion of small-for-gestational-age (SGA) infants detected by routine third-trimester ultrasound vs those detected by selective ultrasound based on serial symphysis-fundus height (SFH) measurements (standard care) in low-risk pregnancy.

METHODS

This was an open-label randomized controlled trial conducted at a hospital in Kenya between May 2018 and February 2020. Low-risk pregnant women were randomly allocated (ratio of 1:1) to routine ultrasound for fetal growth assessment between 36 + 0 and 37 + 6 weeks' gestation (intervention group) or to standard care, which involved a selective growth scan on clinical suspicion of fetal growth abnormality based on serial SFH measurements (control group). During ultrasound examination, fetal growth was assessed by measurement of the abdominal circumference (AC), and AC < 10^th centile was used to diagnose a SGA fetus. The main prespecified outcomes were the detection of neonatal SGA, defined as birth weight < 10^th centile, and of severe neonatal SGA, defined as birth weight < 3^rd centile. The predictive performance of routine third-trimester ultrasound and selective ultrasound based on serial SFH measurements was determined using receiver-operating-characteristics (ROC)-curve analysis.

RESULTS

Of 566 women assessed for eligibility, 508 (89.8%) were randomized, of whom 253 were allocated to the intervention group and 255 to the control group. Thirty-six babies in the intervention group and 26 in the control group had a birth weight < 10^th centile. The detection rate of SGA infants by routine third-trimester ultrasound vs that by standard care was 52.8% (19/36) vs 7.7% (2/26) (P < 0.001) and the specificity was 95.5% (191/200) and 97.9% (191/195), respectively (P = 0.08). The detection rate of severe SGA was 66.7% (12/18) by routine ultrasound vs 8.3% (1/12) by selective ultrasound based on SFH measurements (P < 0.001), with specificities of 91.7% (200/218) and 98.1% (205/209), respectively (P = 0.006). The area under the ROC curve of routine third-trimester ultrasound in prediction of SGA was significantly greater than that of selective ultrasound based on SFH measurements (0.92 (95% CI, 0.87-0.96) vs 0.68 (95% CI, 0.58-0.77); P < 0.001).

CONCLUSIONS

In low-risk pregnancy, routine ultrasound performed between 36 + 0 and 37 + 6 weeks is superior to selective ultrasound based on serial SFH measurements for the detection of true SGA, with high specificity. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Use of the Renal Artery Doppler to Identify Small for Gestational Age Fetuses at Risk for Adverse Neonatal Outcomes

Objective: To measure the sensitivity and positive predictive value (PPV) for an adverse neonatal outcome among growth-restricted fetuses (FGR) comparing the cerebral–placental ratio (CPR) with the cerebral–renal ratio (CRR). Methods: Retrospective analysis of 92 women who underwent prenatal ultrasound at the University of Maryland and the University of Padua. Renal, middle cerebral and umbilical artery Doppler waveforms were recorded for all scans during the third trimester. The last scan prior to delivery was included for analysis. We calculated the test characteristics of the pulsatility indices (PI) of the umbilical and renal arteries in addition to the derived CPR and CRR to detect a composite adverse neonatal outcome. Results: The test characteristics of the four Doppler ratios to detect increased risk for the composite neonatal outcome demonstrated that the umbilical artery pulsatility index had the best test performance (sensitivity 64% (95% CI: 47–82%), PPV 24% (95% CI: 21–27), and positive likelihood ratio 2.7 (95% CI: 1.4–5.2)). There was no benefit to using the CRR compared with the CPR. The agreement between tests was moderate to poor (Kappa value CPR compared with CRR: 0.5 (95%CI 0.4–0.70), renal artery PI:−0.1 (95% CI −0.2–0.0), umbilical artery PI: 0.5 (95% CI 0.4–0.7)). Only the umbilical artery had an area under the receiver operating curve that was significantly better compared with the CPR as a reference (p-value < 0.01). Conclusions: The data that we present do not support the use of renal artery Doppler as a useful clinical test to identify a fetus at risk for an adverse neonatal outcome. Within the various indices applied to this population, umbilical artery Doppler performed the best in identifying the fetuses at risk for an adverse perinatal outcome.

Universal late pregnancy ultrasound screening to predict adverse outcomes in nulliparous women: a systematic review and cost-effectiveness analysis

BACKGROUND

Currently, pregnant women are screened using ultrasound to perform gestational aging, typically at around 12 weeks' gestation, and around the middle of pregnancy. Ultrasound scans thereafter are performed for clinical indications only.

OBJECTIVES

We sought to assess the case for offering universal late pregnancy ultrasound to all nulliparous women in the UK. The main questions addressed were the diagnostic effectiveness of universal late pregnancy ultrasound to predict adverse outcomes and the cost-effectiveness of either implementing universal ultrasound or conducting further research in this area.

DESIGN

We performed diagnostic test accuracy reviews of five ultrasonic measurements in late pregnancy. We conducted cost-effectiveness and value-of-information analyses of screening for fetal presentation, screening for small for gestational age fetuses and screening for large for gestational age fetuses. Finally, we conducted a survey and a focus group to determine the willingness of women to participate in a future randomised controlled trial.

DATA SOURCES

We searched MEDLINE, EMBASE and the Cochrane Library from inception to June 2019.

REVIEW METHODS

The protocol for the review was designed a priori and registered. Eligible studies were identified using keywords, with no restrictions for language or location. The risk of bias in studies was assessed using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) tool. Health economic modelling employed a decision tree analysed via Monte Carlo simulation. Health outcomes were from the fetal perspective and presented as quality-adjusted life-years. Costs were from the perspective of the public sector, defined as NHS England, and the costs of special educational needs. All costs and quality-adjusted life-years were discounted by 3.5% per annum and the reference case time horizon was 20 years.

RESULTS

Umbilical artery Doppler flow velocimetry, cerebroplacental ratio, severe oligohydramnios and borderline oligohydramnios were all either non-predictive or weakly predictive of the risk of neonatal morbidity (summary positive likelihood ratios between 1 and 2) and were all weakly predictive of the risk of delivering a small for gestational age infant (summary positive likelihood ratios between 2 and 4). Suspicion of fetal macrosomia is strongly predictive of the risk of delivering a large infant, but it is only weakly, albeit statistically significantly, predictive of the risk of shoulder dystocia. Very few studies blinded the result of the ultrasound scan and most studies were rated as being at a high risk of bias as a result of treatment paradox, ascertainment bias or iatrogenic harm. Health economic analysis indicated that universal ultrasound for fetal presentation only may be both clinically and economically justified on the basis of existing evidence. Universal ultrasound including fetal biometry was of borderline cost-effectiveness and was sensitive to assumptions. Value-of-information analysis indicated that the parameter that had the largest impact on decision uncertainty was the net difference in cost between an induced delivery and expectant management.

LIMITATIONS

The primary literature on the diagnostic effectiveness of ultrasound in late pregnancy is weak. Value-of-information analysis may have underestimated the uncertainty in the literature as it was focused on the internal validity of parameters, which is quantified, whereas the greatest uncertainty may be in the external validity to the research question, which is unquantified.

CONCLUSIONS

Universal screening for presentation at term may be justified on the basis of current knowledge. The current literature does not support universal ultrasonic screening for fetal growth disorders.

FUTURE WORK

We describe proof-of-principle randomised controlled trials that could better inform the case for screening using ultrasound in late pregnancy.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42017064093.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 25, No. 15. See the NIHR Journals Library website for further project information.

Fetal Growth Restriction - Diagnostic Work-up, Management and Delivery

Fetal or intrauterine growth restriction (FGR/IUGR) affects approximately 5 – 8% of all pregnancies and refers to a fetus not exploiting its genetically determined growth potential. Not only a major cause of perinatal morbidity and mortality, it also predisposes these fetuses to the development of chronic disorders in later life. Apart from the timely diagnosis and identification of the causes of FGR, the obstetric challenge primarily entails continued antenatal management with optimum timing of delivery. In order to minimise premature birth morbidity, intensive fetal monitoring aims to prolong the pregnancy and at the same time intervene, i.e. deliver, before the fetus is threatened or harmed. It is important to note that early-onset FGR (< 32 + 0 weeks of gestation [wks]) should be assessed differently than late-onset FGR (≥ 32 + 0 wks). In early-onset FGR progressive deterioration is reflected in abnormal venous Doppler parameters, while in late-onset FGR this manifests primarily in abnormal cerebral Doppler ultrasound. According to our current understanding, the “optimum” approach for monitoring and timing of delivery in early-onset FGR combines computerized CTG with the ductus venosus Doppler, while in late-onset FGR assessment of the cerebral Doppler parameters becomes more important.

Third-trimester uterine artery Doppler for prediction of adverse outcome in late small-for-gestational-age fetuses: systematic review and meta-analysis

OBJECTIVE

To investigate the predictive ability for adverse perinatal outcome of abnormal third-trimester uterine artery Doppler in late small-for-gestational-age (SGA) fetuses.

METHODS

A systematic search was performed to identify relevant observational studies and randomized controlled trials evaluating the performance of abnormal third-trimester uterine artery Doppler for the prediction of adverse perinatal outcome in suspected SGA fetuses and SGA neonates. Abnormal uterine artery Doppler was defined as uterine artery pulsatility index > 95^th percentile or ≥ 2 SD above the mean, or bilateral uterine artery notching. Hierarchical summary receiver-operating-characteristics (ROC) curves were constructed using random-effects modeling. Bayesian analysis was used to calculate the posterior probability of adverse perinatal outcome following an abnormal or normal uterine artery Doppler assessment.

RESULTS

Seventeen observational studies (including 7552 fetuses either diagnosed with suspected SGA (n = 3461) or later diagnosed as a SGA neonate (n = 4091)) met the inclusion criteria; no randomized-controlled trials met the inclusion criteria. Summary ROC curves showed that, among suspected SGA fetuses, the best predictive accuracy of abnormal third-trimester uterine artery Doppler was for perinatal mortality and the worst was for composite adverse perinatal outcome, with areas under the summary ROC curves of 0.90 and 0.66, respectively. The corresponding positive and negative likelihood ratios were 16.5 and 0.6 for perinatal mortality and 2.82 and 0.65 for composite adverse perinatal outcome, respectively. Following an abnormal vs normal uterine artery Doppler assessment, the posterior risks for composite adverse perinatal outcome, admission to the neonatal intensive care unit, Cesarean section for intrapartum fetal compromise, 5-min Apgar score < 7, neonatal acidosis and perinatal death were: 52.3% vs 20.2%, 48.6% vs 18.7%, 23.1% vs 15.2%, 3.59% vs 1.32%, 9.15% vs 5.12% and 31.4% vs 1.64%, respectively.

CONCLUSION

Abnormal uterine artery Doppler in the third trimester appears to be moderately useful in predicting perinatal death in pregnancies with suspected SGA. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Local cerebroplacental ratio reference ranges are better predictors for adverse delivery outcomes in normal weight fetuses during pregnancy

Objective: To evaluate the predictive value of local versus external cerebroplacental ratio (CPR) reference ranges for delivery outcomes in low-risk pregnancies.Methods: A retrospective analysis of all feto-maternal demographic and biometric data in fetuses with normal estimated fetal weight (EFW) and a CPR examination between the years 2014-2019, in a university medical center. The study group included healthy singleton pregnancies from 32-week gestation, with an examination-to-delivery interval of <31 days. The three models compared two thresholds: <5th percentile (CPR 1, CPR 3) and <10th percentile (CPR2). The CPR1 and CPR2 models both use local CPR reference ranges, while the CPR3 model uses an external CPR reference range. The main outcome was predictive accuracy for urgent cesarean delivery (CD), operative delivery (OD), and composite outcome (CO), defined as an Apgar score of <7, fetal blood pH < 7.1 or admission to the neonatal intensive care unit (NICU).Results: Overall, 410 low-risk pregnancies with normal weight fetuses were enrolled in the study. All three CPR models turned out to be significant predictors of CD, with an odds ratio (OR) of 9, 95% CI (2.7-27), p < .001 for CPR1, and an OR of 2.9, 95% CI (1.1-7.4), p < .04 for CPR2, and an OR of 3.4, 95% CI (1.7-6.8), p < .001 for CPR3. All the three models were also found to be predictors of OD, and an OR of 6.9, 95% CI (2.1-22) p < .04 for CPR1, and an OR of 2.8, 95% CI (1.2-6.7), p < .04 for CPR2, and an OR of 2.8, 95% CI (1.4-5.3) p < .01 for CPR3. The positive predictive values (PPV) for CD and OD were both 50% for CPR1, versus 28% and 26% in CPR2, and 24% and 25% in CPR3. The negative predictive value (NPV) was similar, around 88% in all three models. None of the models were found to be significant predictors for CO.Conclusions: A CPR model based on local reference ranges and <5th percentile cutoffs showed the highest PPV for CD and OD. The calculation of local references for CPR should be encouraged.

Third-trimester Reference Ranges for Cerebroplacental Ratio and Pulsatility Index for Middle Cerebral Artery and Umbilical Artery in Normal-growth Singleton Fetuses in the Israeli Population

BACKGROUND

The ratio between the fetal umbilical artery pulsatility index (UA-PI) and the middle cerebral artery pulsatility index (MCA-PI) is termed the cerebroplacental ratio (CPR). The CPR represents fetal blood flow redistribution at the early stages of placental insufficiency; moreover, it has predictive value for adverse intrapartum and neonatal outcomes. However, internationally accepted reference ranges for CPR are lacking.

OBJECTIVE

This study sought to establish UA-PI, MCA-PI, and CPR reference ranges in low-risk, normal-growth singleton fetuses during the third trimester of pregnancy.

METHODS

A retrospective cohort cross-sectional study was performed in the obstetrics ultrasound unit of a university hospital in Israel. We reviewed all fetal and maternal electronic records of pregnant women referred for ultrasound assessment during the third trimester between January 2014 and January 2019. We included only singleton pregnancies with normal anatomy scans and a normal third-trimester estimated fetal weight. The UA-PI, MCA-PI, and CPR reference ranges were reconstructed for each of the vessels for each gestational age between 29 and 41 weeks.

RESULTS

A total of 560 pregnancies met the inclusion criteria. Satisfactory waveforms and measurements were obtained in all cases. At least 18 women enrolled at each gestational week. The MCA-PI and CPR values showed a similar parabolic curve during the third trimester of pregnancy, with a peak value at 32 and 33 gestational weeks, respectively. The UA-PI showed a linear and gradual decrease over the gestational age.

CONCLUSIONS

In this study we established UA-PI, MCA-PI, and CPR reference ranges in low-risk, normal-growth singleton fetuses during the third trimester based on the Israeli population.

Renal artery Doppler compared with the cerebral placental ratio to identify fetuses at risk for adverse neonatal outcome

Background: Current clinical practice incorporates an umbilical artery resistance index or a ratio of the middle cerebral artery (MCA PI) to the umbilical artery pulsatility index (UA PI) known as the cerebral placental ratio (CPR) to assess wellbeing in the small for gestational age fetus. Previous reports using the renal artery Doppler indices have not been consistent in regards to their design and clinical use. Our objective is to develop reference values for renal artery Doppler indices and validate their use compared with the UA PI or CPR to identify fetuses that will develop a composite neonatal outcome.Methods: We performed 9700 ultrasounds among 2852 women at 20-40 weeks of gestation at the University of Maryland between 1 June 2016 and 1 December 2016. Nomograms were first developed using one randomly selected scan from each of a subgroup of 860 women without any comorbidities. The nomograms were validated among a cohort of 550 women who subsequently delivered at the University of Maryland Medical Center. We compared the area under the receiver operating characteristic curve (AUROC) between the CPR and UA PI, and the renal artery Doppler parameters (renal artery pulsatility index (RA PI), systolic diastolic ratio (RA SDR), and peak systolic velocity (RA PSV)). The primary outcome was the development any one of the composite neonatal outcome components (death, intensive care unit admission, ventilator for more than 6 h, hypoxic ischemic encephalopathy or necrotizing enterocolitis) or admission to the neonatal intensive care unit (NICU) for any indication.Results: The renal artery Doppler indices did not improve identification of fetuses that would subsequently develop one of the components of the composite neonatal outcome (AUROC for CPR 0.54, 95% CI (0.49-0.59), versus the UA PI: 0.59 (0.54-0.64) p = .07, the RA PI: 0.51 (0.48-0.55) p = .41, RA SDR 0.54 (0.49-0.58) p = .99, or RA PSV 0.51 (0.47-0.55) p = .37). There was no difference when comparing AUROC to detect NICU admission (AUROC for CPR 0.53, 95% CI (0.49-0.58), versus the UA PI: 0.57 (0.52-0.62) p = .14, the RA PI: 0.50 (0.47-0.54) p = .44, RA SDR: 0.54 (0.50-0.59) p = .62 or RAPSV: 0.51 (0.47-0.55) p = .54).Conclusion: The renal artery indices do not improve detection of fetuses at risk for adverse neonatal outcomes compared with the CPR or the UA PI.