Screening for the compromised fetus: a randomized trial of umbilical artery velocimetry in unselected pregnancies

[Fetal death: Expert consensus from the College of French Gynecologists and Obstetricians]

Fetal death is defined as the spontaneous cessation of cardiac activity after fourteen weeks of amenorrhea. In France, the prevalence of fetal death after 22 weeks is between 3.2 and 4.4/1000 births. Regarding the prevention of fetal death in the general population, it is not recommended to counsel for rest and not to prescribe vitamin A, vitamin D nor micronutrient supplementation for the sole purpose of reducing the risk of fetal death (Weak recommendations; Low quality of evidence). It is not recommended to prescribe aspirin (Weak recommendation; Very low quality of evidence). It is recommended to offer vaccination against influenza in epidemic periods and against SARS-CoV-2 (Strong recommendations; Low quality of evidence). It is not recommended to systematically look for nuchal cord encirclements during prenatal screening ultrasounds (Strong Recommendation; Low Quality of Evidence) and not to perform systematic antepartum monitoring by cardiotocography (Weak Recommendation; Very Low Quality of Evidence). It is not recommended to ask women to perform an active fetal movement count to reduce the risk of fetal death (Strong Recommendation; High Quality of Evidence). Regarding evaluation in the event of fetal death, it is suggested that an external fetal examination be systematically offered (Expert opinion). It is recommended that a fetopathological and anatomopathological examination of the placenta be carried out to participate in cause identification (Strong Recommendation. Moderate quality of evidence). It is recommended that chromosomal analysis by microarray testing be performed rather than conventional karyotype, in order to be able to identify a potentially causal anomaly more frequently (Strong Recommendation, moderate quality of evidence); to this end, it is suggested that postnatal sampling of the placental fetal surface for genetic purposes be preferred (Expert Opinion). It is suggested to test for antiphospholipid antibodies and systematically perform a Kleihauer test and a test for irregular agglutinins (Expert opinion). It is suggested to offer a summary consultation, with the aim of assessing the physical and psychological status of the parents, reporting the results, discussing the cause and providing information on monitoring for a subsequent pregnancy (Expert opinion). Regarding announcement and support, it is suggested to announce fetal death without ambiguity, using simple words and adapting to each situation, and then to support couples with empathy in the various stages of their care (Expert opinion). Regarding management, it is suggested that, in the absence of a situation at risk of disseminated intravascular coagulation or maternal vitality, the patient's wishes should be taken into account when determining the time between the diagnosis of fetal death and induction of birth. Returning home is possible if it's the patient wish (Expert opinion). In all situations excluding maternal life-threatening emergencies, the preferred mode of delivery is vaginal delivery, regardless the history of cesarean section(s) history (Expert opinion). In the event of fetal death, it is recommended that mifepristone 200mg be prescribed at least 24hours before induction, to reduce the delay between induction and delivery (Low recommendation. Low quality of evidence). There are insufficient data in the literature to make a recommendation regarding the route of administration (vaginal or oral) of misoprostol, neither the type of prostaglandin to reduce induction-delivery time or maternal morbidity. It is suggested that perimedullary analgesia be introduced at the start of induction if the patient asks, regardless of gestational age. It is suggested to prescribe cabergoline immediately in the postpartum period in order to avoid lactation, whatever the gestational age, after discussing the side effects of the treatment with the patient (Expert opinion). The risk of recurrence of fetal death after unexplained fetal death does not appear to be increased in subsequent pregnancies, and data from the literature are insufficient to make a recommendation on the prescription of aspirin. In the event of a history of fetal death due to vascular issues, low-dose aspirin is recommended to reduce perinatal morbidity, and should not be combined with heparin therapy (Low recommendation, very low quality of evidence). It is suggested not to recommend an optimal delay before initiating another pregnancy just because of the history of fetal death. It is suggested that the woman and co-parent be informed of the possibility of psychological support. Fetal heart rate monitoring is not indicated solely because of a history of fetal death. It is suggested that delivery not be systematically induced. However, induction can be considered depending on the context and parental request. The gestational age will be discussed, taking into account the benefits and risks, especially before 39 weeks. If a cause of fetal death is identified, management will be adapted on a case-by-case basis (expert opinion). In the event of fetal death occurring in a twin pregnancy, it is suggested that the surviving twin be evaluated as soon as the diagnosis of fetal death is made. In the case of dichorionic pregnancy, it is suggested to offer ultrasound monitoring on a monthly basis. It is suggested not to deliver prematurely following fetal death of a twin. If fetal death occurs in a monochorionic twin pregnancy, it is suggested to contact the referral competence center, in order to urgently look for signs of acute fetal anemia on ultrasound in the surviving twin, and to carry out weekly ultrasound monitoring for the first month. It is suggested not to induce birth immediately.

Fetal and umbilical Doppler ultrasound in high-risk pregnancies

BACKGROUND

Abnormal blood flow patterns in fetal circulation detected by Doppler ultrasound may indicate poor fetal prognosis. It is also possible that false positive Doppler ultrasound findings could lead to adverse outcomes from unnecessary interventions, including preterm delivery.

OBJECTIVES

The objective of this review was to assess the effects of Doppler ultrasound used to assess fetal well-being in high-risk pregnancies on obstetric care and fetal outcomes.

SEARCH METHODS

We updated the search of Cochrane Pregnancy and Childbirth's Trials Register on 31 March 2017 and checked reference lists of retrieved studies.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials of Doppler ultrasound for the investigation of umbilical and fetal vessels waveforms in high-risk pregnancies compared with no Doppler ultrasound. Cluster-randomised trials were eligible for inclusion but none were identified.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the studies for inclusion, assessed risk of bias and carried out data extraction. Data entry was checked. We assessed the quality of evidence using the GRADE approach.

MAIN RESULTS

Nineteen trials involving 10,667 women were included. Risk of bias in trials was difficult to assess accurately due to incomplete reporting. None of the evidence relating to our main outcomes was graded as high quality. The quality of evidence was downgraded due to missing information on trial methods, imprecision in risk estimates and heterogeneity. Eighteen of these studies compared the use of Doppler ultrasound of the umbilical artery of the unborn baby with no Doppler or with cardiotocography (CTG). One more recent trial compared Doppler examination of other fetal blood vessels (ductus venosus) with computerised CTG.The use of Doppler ultrasound of the umbilical artery in high-risk pregnancy was associated with fewer perinatal deaths (risk ratio (RR) 0.71, 95% confidence interval (CI) 0.52 to 0.98, 16 studies, 10,225 babies, 1.2% versus 1.7 %, number needed to treat (NNT) = 203; 95% CI 103 to 4352, evidence graded moderate). The results for stillbirths were consistent with the overall rate of perinatal deaths, although there was no clear difference between groups for this outcome (RR 0.65, 95% CI 0.41 to 1.04; 15 studies, 9560 babies, evidence graded low). Where Doppler ultrasound was used, there were fewer inductions of labour (average RR 0.89, 95% CI 0.80 to 0.99, 10 studies, 5633 women, random-effects, evidence graded moderate) and fewer caesarean sections (RR 0.90, 95% CI 0.84 to 0.97, 14 studies, 7918 women, evidence graded moderate). There was no comparative long-term follow-up of babies exposed to Doppler ultrasound in pregnancy in women at increased risk of complications.No difference was found in operative vaginal births (RR 0.95, 95% CI 0.80 to 1.14, four studies, 2813 women), nor in Apgar scores less than seven at five minutes (RR 0.92, 95% CI 0.69 to 1.24, seven studies, 6321 babies, evidence graded low). Data for serious neonatal morbidity were not pooled due to high heterogeneity between the three studies that reported it (1098 babies) (evidence graded very low).The use of Doppler to evaluate early and late changes in ductus venosus in early fetal growth restriction was not associated with significant differences in any perinatal death after randomisation. However, there was an improvement in long-term neurological outcome in the cohort of babies in whom the trigger for delivery was either late changes in ductus venosus or abnormalities seen on computerised CTG.

AUTHORS' CONCLUSIONS

Current evidence suggests that the use of Doppler ultrasound on the umbilical artery in high-risk pregnancies reduces the risk of perinatal deaths and may result in fewer obstetric interventions. The results should be interpreted with caution, as the evidence is not of high quality. Serial monitoring of Doppler changes in ductus venosus may be beneficial, but more studies of high quality with follow-up including neurological development are needed for evidence to be conclusive.

Role of the fetoplacental endothelium in fetal growth restriction with abnormal umbilical artery Doppler velocimetry

Growth-restricted fetuses with absent or reversed end-diastolic velocities in the umbilical artery are at substantially increased risk for adverse perinatal and long-term outcome, even in comparison to growth-restricted fetuses with preserved end-diastolic velocities. Translational studies show that this Doppler velocimetry correlates with fetoplacental blood flow, with absent or reversed end-diastolic velocities signifying abnormally elevated resistance within the placental vasculature. The fetoplacental vasculature is unique in that it is not subject to autonomic regulation, unlike other vascular beds. Instead, humoral mediators, many of which are synthesized by local endothelial cells, regulate placental vascular resistance. Existing data demonstrate that in growth-restricted pregnancies complicated by absent or reversed umbilical artery end-diastolic velocities, an imbalance in production of these vasoactive substances occurs, favoring vasoconstriction. Morphologically, placentas from these pregnancies also demonstrate impaired angiogenesis, whereby vessels within the terminal villi are sparsely branched, abnormally thin, and elongated. This structural deviation from normal placental angiogenesis restricts blood flow and further contributes to elevated fetoplacental vascular resistance. Although considerable work has been done in the field of fetoplacental vascular development and function, much remains unknown about the mechanisms underlying impaired development and function of the human fetoplacental vasculature, especially in the context of severe fetal growth restriction with absent or reversed umbilical artery end-diastolic velocities. Fetoplacental endothelial cells are key regulators of angiogenesis and vasomotor tone. A thorough understanding of their role in placental vascular biology carries the significant potential of discovering clinically relevant and innovative approaches to prevention and treatment of fetal growth restriction with compromised umbilical artery end-diastolic velocities.

Fetal and umbilical Doppler ultrasound in normal pregnancy

BACKGROUND

One of the main aims of routine antenatal care is to identify the 'at risk' fetus in order to apply clinical interventions which could result in reduced perinatal morbidity and mortality. Doppler ultrasound study of umbilical artery waveforms helps to identify the compromised fetus in 'high-risk' pregnancies and, therefore, deserves assessment as a screening test in 'low-risk' pregnancies.

OBJECTIVES

To assess the effects on obstetric practice and pregnancy outcome of routine fetal and umbilical Doppler ultrasound in unselected and low-risk pregnancies.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group Trials Register (28 February 2015) and reference lists of retrieved studies.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials of Doppler ultrasound for the investigation of umbilical and fetal vessels waveforms in unselected pregnancies compared with no Doppler ultrasound. Studies where uterine vessels have been assessed together with fetal and umbilical vessels have been included.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the studies for inclusion, assessed risk of bias and carried out data extraction. In addition to standard meta-analysis, the two primary outcomes and five of the secondary outcomes were assessed using GRADE software and methodology.

MAIN RESULTS

We included five trials that recruited 14,624 women, with data analysed for 14,185 women. All trials had adequate allocation concealment, but none had adequate blinding of participants, staff or outcome assessors. Overall and apart from lack of blinding, the risk of bias for the included trials was considered to be low.Overall, routine fetal and umbilical Doppler ultrasound examination in low-risk or unselected populations did not result in increased antenatal, obstetric and neonatal interventions. There were no group differences noted for the review's primary outcomes of perinatal death and neonatal morbidity. Results for perinatal death were as follows: (average risk ratio (RR) 0.80, 95% confidence interval (CI) 0.35 to 1.83; four studies, 11,183 participants). Only one included trial assessed serious neonatal morbidity and found no evidence of group differences (RR 0.99, 95% CI 0.06 to 15.75; one study, 2016 participants).For the comparison of a single Doppler assessment versus no Doppler, evidence for group differences in perinatal death was detected (RR 0.36, 95% CI 0.13 to 0.99; one study, 3891 participants). However, these results are based on a single trial, and we would recommend caution when interpreting this finding.There was no evidence of group differences for the outcomes of caesarean section, neonatal intensive care admissions or preterm birth less than 37 weeks.When the quality of the evidence for the main comparison of 'All Doppler versus no Doppler' was assessed with GRADE software, the outcomes of perinatal death and serious neonatal morbidity data were graded as of low quality. Evidence for the outcome of stillbirth was graded according to regimen subgroups - with a moderate quality rating for stillbirth (fetal/umbilical vessels only) and a low quality rating for stillbirth (fetal/umbilical vessels + uterine artery vessels). Evidence for admission to neonatal intensive care unit was assessed as of moderate quality, and evidence for the outcomes of caesarean section and preterm birth less than 37 weeks was graded as of high quality.There is no available evidence to assess the effect on substantive long-term outcomes such as childhood neurodevelopment and no data to assess maternal outcomes, particularly maternal satisfaction.

AUTHORS' CONCLUSIONS

Existing evidence does not provide conclusive evidence that the use of routine umbilical artery Doppler ultrasound, or combination of umbilical and uterine artery Doppler ultrasound in low-risk or unselected populations benefits either mother or baby. Future studies should be designed to address small changes in perinatal outcome, and should focus on potentially preventable deaths.

Fetal and umbilical Doppler ultrasound in high-risk pregnancies

BACKGROUND

Abnormal blood flow patterns in fetal circulation detected by Doppler ultrasound may indicate poor fetal prognosis. It is also possible false positive Doppler ultrasound findings could encourage inappropriate early delivery.

OBJECTIVES

The objective of this review was to assess the effects of Doppler ultrasound used to assess fetal well-being in high-risk pregnancies on obstetric care and fetal outcomes.

SEARCH METHODS

We updated the search of the Cochrane Pregnancy and Childbirth Group's Trials Register on 30 September 2013.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials of Doppler ultrasound for the investigation of umbilical and fetal vessels waveforms in high-risk pregnancies compared with no Doppler ultrasound.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the studies for inclusion, assessed risk of bias and carried out data extraction. Data entry was checked.

MAIN RESULTS

Eighteen completed studies involving just over 10,000 women were included. The trials were generally of unclear quality with some evidence of possible publication bias. The use of Doppler ultrasound in high-risk pregnancy was associated with a reduction in perinatal deaths (risk ratio (RR) 0.71, 95% confidence interval (CI) 0.52 to 0.98, 16 studies, 10,225 babies, 1.2% versus 1.7 %, number needed to treat (NNT) = 203; 95% CI 103 to 4352). There were also fewer inductions of labour (average RR 0.89, 95% CI 0.80 to 0.99, 10 studies, 5633 women, random-effects) and fewer caesarean sections (RR 0.90, 95% CI 0.84 to 0.97, 14 studies, 7918 women). No difference was found in operative vaginal births (RR 0.95, 95% CI 0.80 to 1.14, four studies, 2813 women), nor in Apgar scores less than seven at five minutes (RR 0.92, 95% CI 0.69 to 1.24, seven studies, 6321 babies).

AUTHORS' CONCLUSIONS

Current evidence suggests that the use of Doppler ultrasound in high-risk pregnancies reduced the risk of perinatal deaths and resulted in less obstetric interventions. The quality of the current evidence was not of high quality, therefore, the results should be interpreted with some caution. Studies of high quality with follow-up studies on neurological development are needed.

Two-dimensional and three-dimensional Doppler assessment of fetal growth restriction with different severity and onset

OBJECTIVES

To investigate the role of three-dimensional (3D) power Doppler ultrasonography in the assessment of fetal growth-restriction (FGR) with various degrees of severity and onset, and compare the results with the analysis of two-dimensional (2D) Doppler.

STUDY DESIGN

Vascular indices extracted from 3D Doppler measurements of the placenta were compared with indices of flow-velocity waveforms extracted from 2D Doppler measurements of the major sites of the fetal circulation between FGR (study group) and uncomplicated pregnancies (control group) from 25 to 38 weeks' gestation.

RESULTS

Three-dimensional indices were significantly lower in pregnancies complicated by FGR compared with uncomplicated pregnancies. When measured in placental periphery, vascularization index was 9.4 ± 9.6 in FGR pregnancies compared with 16 ± 14.7, P = 0.04. Flow index was 33.9 ± 6.9 compared with 38.7 ± 4.9, P = 0.03 and the vascularization-flow index was 3.8 ± 4.3 compared with 6.5 ± 6, respectively, P = 0.03. Among the conventional 2D indices, umbilical artery and middle cerebral artery pulsatility indices were not significantly different between the FGR and control groups. Higher rate of maternal or fetal compartment vascular lesions were detected in the FGR group.

CONCLUSIONS

Three-dimensional Doppler was found to be more strongly associated with placental vascular compromise than conventional 2D Doppler, regardless of severity and onset of fetal growth restriction.

Screening and triage of intrauterine growth restriction (IUGR) in general population and high risk pregnancies: a systematic review with a focus on reduction of IUGR related stillbirths

BACKGROUND

There is a strong association between stillbirth and fetal growth restriction. Early detection and management of IUGR can lead to reduce related morbidity and mortality. In this paper we have reviewed effectiveness of fetal movement monitoring and Doppler velocimetry for the detection and surveillance of high risk pregnancies and the effect of this on prevention of stillbirths. We have also reviewed effect of maternal body mass index (BMI) screening, symphysial-fundal height measurement and targeted ultrasound in detection and triage of IUGR in the community.

METHODS

We systematically reviewed all published literature to identify studies related to our interventions. We searched PubMed, Cochrane Library, and all World Health Organization Regional Databases and included publications in any language. Quality of available evidence was assessed using GRADE criteria. Recommendations were made for the Lives Saved Tool (LiST) based on rules developed by the Child Health Epidemiology Group. Given the paucity of evidence related to the effect of detection and management of IUGR on stillbirths, we undertook Delphi based evaluation from experts in the field.

RESULTS

There was insufficient evidence to recommend against or in favor of routine use of fetal movement monitoring for fetal well being. (1) Detection and triage of IUGR with the help of (1a) maternal BMI screening, (1b) symphysial-fundal height measurement and (1c) targeted ultrasound can be an effective method of reducing IUGR related perinatal morbidity and mortality. Pooled results from sixteen studies shows that Doppler velocimetry of umbilical and fetal arteries in 'high risk' pregnancies, coupled with the appropriate intervention, can reduce perinatal mortality by 29 % [RR 0.71, 95 % CI 0.52-0.98]. Pooled results for impact on stillbirth showed a reduction of 35 % [RR 0.65, 95 % CI 0.41-1.04]; however, the results did not reach the conventional limits of statistical significance. This intervention could be potentially recommended for high income settings or middle income countries with improving rates and standards of facility based care. Based on the Delphi, a combination of screening with maternal BMI, Symphysis fundal height and targeted ultrasound followed by the appropriate management could potentially reduce antepartum and intrapartum stillbirth by 20% respectively. This estimate is presently being recommended for inclusion in the LiST.

CONCLUSION

There is insufficient evidence to recommend in favor or against fetal movement counting for routine use for testing fetal well being. Doppler velocimetry of umbilical and fetal arteries and appropriate intervention is associated with 29 % (95 % CI 2% to 48 %) reduction in perinatal mortality. Expert opinion suggests that detection and management of IUGR with the help of maternal BMI, symphysial-fundal height measurement and targeted ultrasound could be effective in reducing IUGR related stillbirths by 20%.

Umbilical artery Doppler in the assessment of fetal growth restriction

Antepartum fetal surveillance with Doppler ultrasound of umbilical artery has shown significant diagnostic efficacy in identifying fetal compromise in pregnancies complicated with fetal growth restriction (FGR). Its effectiveness in decreasing perinatal mortality has been shown by randomized clinical trials (Level I evidence). This test is the only antepartum fetal test that has shown this level of effectiveness and should be the standard of practice in managing FGR (Level A recommendation). The overall management considerations should encompass other standard fetal monitoring tests (Level B and C recommendations).

Utero-placental Doppler ultrasound for improving pregnancy outcome

BACKGROUND

Impaired placentation can cause some of the most important obstetrical complications such as pre-eclampsia and intrauterine growth restriction and has been linked to increased fetal morbidity and mortality. The failure to undergo physiological trophoblastic vascular changes is reflected by the high impedance to the blood flow at the level of the uterine arteries. Doppler ultrasound study of utero-placental blood vessels, using waveform indices or notching, may help to identify the 'at-risk' women in the first and second trimester of pregnancy, such that interventions might be used to reduce maternal and fetal morbidity and/or mortality.

OBJECTIVES

To assess the effects on pregnancy outcome, and obstetric practice, of routine utero-placental Doppler ultrasound in first and second trimester of pregnancy in pregnant women at high and low risk of hypertensive complications.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (June 2010) and the reference lists of identified studies.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials of Doppler ultrasound for the investigation of utero-placental vessel waveforms in first and second trimester compared with no Doppler ultrasound. We have excluded studies where uterine vessels have been assessed together with fetal and umbilical vessels.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the studies for inclusion, assessed risk of bias and carried out data extraction. We checked data entry.

MAIN RESULTS

We found two studies involving 4993 participants. The methodological quality of the trials was good. Both studies included women at low risk for hypertensive disorders, with Doppler ultrasound of the uterine arteries performed in the second trimester of pregnancy. In both studies, pathological finding of uterine arteries was followed by low-dose aspirin administration.We identified no difference in short-term maternal and fetal clinical outcomes.We identified no randomised studies assessing the utero-placental vessels in the first trimester or in women at high risk for hypertensive disorders.

AUTHORS' CONCLUSIONS

Present evidence failed to show any benefit to either the baby or the mother when utero-placental Doppler ultrasound was used in the second trimester of pregnancy in women at low risk for hypertensive disorders. Nevertheless, this evidence cannot be considered conclusive with only two studies included. There were no randomised studies in the first trimester, or in women at high risk. More research is needed to investigate whether the use of utero-placental Doppler ultrasound may improve pregnancy outcome.

Fetal and umbilical Doppler ultrasound in normal pregnancy

BACKGROUND

One of the main aims of routine antenatal care is to identify the 'at risk' fetus in order to apply clinical interventions which could result in reduced perinatal morbidity and mortality. Doppler ultrasound study of umbilical artery waveforms helps to identify the compromised fetus in 'high-risk' pregnancies and, therefore, deserves assessment as a screening test in 'low-risk' pregnancies.

OBJECTIVES

To assess the effects on obstetric practice and pregnancy outcome of routine fetal and umbilical Doppler ultrasound in unselected and low-risk pregnancies.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group Trials Register (May 2010).

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials of Doppler ultrasound for the investigation of umbilical and fetal vessels waveforms in unselected pregnancies compared to no Doppler ultrasound. Studies where uterine vessels have been assessed together with fetal and umbilical vessels have been included.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the studies for inclusion, assessed risk of bias and carried out data extraction.

MAIN RESULTS

We included five trials involving 14,185 women. The methodological quality of the trials was generally unclear because of insufficient data included in the reports.Routine fetal and umbilical Doppler ultrasound examination in low-risk or unselected populations did not result in increased antenatal, obstetric and neonatal interventions, and no overall differences were detected for substantive short term clinical outcomes such as perinatal mortality. There is no available evidence to assess the effect on substantive long term outcomes such as childhood neurodevelopment and no data to assess maternal outcomes, particularly psychological effects.

AUTHORS' CONCLUSIONS

Existing evidence does not provide conclusive evidence that the use of routine umbilical artery Doppler ultrasound, or combination of umbilical and uterine artery Doppler ultrasound in low-risk or unselected populations benefits either mother or baby. Future studies should be designed to address small changes in perinatal outcome, and should focus on potentially preventable deaths.

Fetal and umbilical Doppler ultrasound in high-risk pregnancies

BACKGROUND

Abnormal blood flow patterns in fetal circulation detected by Doppler ultrasound may indicate poor fetal prognosis. It is also possible false positive Doppler ultrasound findings could encourage inappropriate early delivery.

OBJECTIVES

The objective of this review was to assess the effects of Doppler ultrasound used to assess fetal well-being in high-risk pregnancies on obstetric care and fetal outcomes.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (September 2009) and the reference lists of identified studies.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials of Doppler ultrasound for the investigation of umbilical and fetal vessels waveforms in high-risk pregnancies compared to no Doppler ultrasound.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the studies for inclusion, assessed risk of bias and carried out data extraction. Data entry was checked.

MAIN RESULTS

Eighteen completed studies involving just over 10,000 women were included. The trials were generally of unclear quality with some evidence of possible publication bias. The use of Doppler ultrasound in high-risk pregnancy was associated a reduction in perinatal deaths (risk ratio (RR) 0.71, 95% confidence interval (CI) 0.52 to 0.98, 16 studies, 10,225 babies, 1.2% versus 1.7 %, numbers needed to treat = 203; 95%CI 103 to 4352). There were also fewer inductions of labour (average RR 0.89, 95% CI 0.80 to 0.99, 10 studies, 5633 women, random effects) and fewer caesarean sections (RR 0.90, 95% CI 0.84 to 0.97, 14 studies, 7918 women). No difference was found in operative vaginal births (RR 0.95, 95% CI 0.80 to 1.14, four studies, 2813 women) nor in Apgar scores less than seven at five minutes (RR 0.92, 95% CI 0.69 to 1.24, seven studies, 6321 babies).

AUTHORS' CONCLUSIONS

Current evidence suggests that the use of Doppler ultrasound in high-risk pregnancies reduced the risk of perinatal deaths and resulted in less obstetric interventions. The quality of the current evidence was not of high quality, therefore, the results should be interpreted with some caution. Studies of high quality with follow-up studies on neurological development are needed.

WITHDRAWN. Doppler ultrasound for fetal assessment in high risk pregnancies

BACKGROUND

Abnormal waveforms from Doppler ultrasound may indicate poor fetal prognosis. It is also possible that Doppler ultrasound could encourage inappropriate early delivery.

OBJECTIVES

The objective of this review was to assess the effects of Doppler ultrasound in high risk pregnancies on obstetric care and fetal outcomes.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group trials register. Date of last search: June 2001.

SELECTION CRITERIA

Randomised trials of Doppler ultrasound for the investigation of umbilical artery waveforms in high risk pregnancies compared to no Doppler ultrasound.

DATA COLLECTION AND ANALYSIS

Trial quality was assessed and data were extracted by both reviewers. Study authors were contacted for additional information.

MAIN RESULTS

Eleven studies involving nearly 7000 women were included. The trials were generally of good quality. Compared to no Doppler ultrasound, Doppler ultrasound in high risk pregnancy (especially those complicated by hypertension or presumed impaired fetal growth) was associated with a trend to a reduction in perinatal deaths (odds ratio 0.71, 95% confidence interval 0.50 to 1.01). The use of Doppler ultrasound was also associated with fewer inductions of labour (odds ratio 0.83, 95% confidence interval 0.74 to 0.93) and fewer admissions to hospital (odds ratio 0.56, 95% 0.43 to 0.72), without reports of adverse effects. No difference was found for fetal distress in labour (odds ratio 0.81, 95% confidence interval 0.59 to 1.13) or caesarean delivery (odds ratio 0.94, 95% 0.82 to 1.06).

AUTHORS' CONCLUSIONS

The use of Doppler ultrasound in high risk pregnancies appears to improve a number of obstetric care outcomes and appears promising in helping to reducing perinatal deaths.

Morphological and functional evaluation of normal and abnormal fetal growth by ultrasonography

Correction or estimation of gestational age is essential for the evaluation of fetal growth. When necessary, an appropriate fetal biometric parameter should be selected depending on fetal size. In the first trimester, crown-rump length (CRL) is appropriate, especially when the CRL is 20-40 mm. In the second trimester, biparietal diameter (BPD), head circumference (HC), and femur length (FL) are of equal predictability. Fetal weight estimation is still the basis of evaluation of fetal growth. The most predictable formula currently available includes the parameters BPD (or HC), abdominal circumference (AC), and FL. Serial measurements of AC are useful for diagnosis of intrauterine growth restriction (IUGR) and macrosomia. Quantitative evaluation of soft tissue deposition may be informative for macrosomia. Functional evaluation using Doppler velocimetry is essential in IUGR cases associated with uteroplacental insufficiency. Analysis of blood velocity waveforms of the umbilical and intracranial arteries, predominantly the middle cerebral artery, is widely performed. An increase in the pulsatility index (PI) or resistance index (RI) of the umbilical artery and/or a decrease in the PI or RI of the middle cerebral artery are highly predictable for fetal hypoxia and/or acidosis.

Reducing stillbirths: screening and monitoring during pregnancy and labour

BACKGROUND

Screening and monitoring in pregnancy are strategies used by healthcare providers to identify high-risk pregnancies so that they can provide more targeted and appropriate treatment and follow-up care, and to monitor fetal well-being in both low- and high-risk pregnancies. The use of many of these techniques is controversial and their ability to detect fetal compromise often unknown. Theoretically, appropriate management of maternal and fetal risk factors and complications that are detected in pregnancy and labour could prevent a large proportion of the world's 3.2 million estimated annual stillbirths, as well as minimise maternal and neonatal morbidity and mortality.

METHODS

The fourth in a series of papers assessing the evidence base for prevention of stillbirths, this paper reviews available published evidence for the impact of 14 screening and monitoring interventions in pregnancy on stillbirth, including identification and management of high-risk pregnancies, advanced monitoring techniques, and monitoring of labour. Using broad and specific strategies to search PubMed and the Cochrane Library, we identified 221 relevant reviews and studies testing screening and monitoring interventions during the antenatal and intrapartum periods and reporting stillbirth or perinatal mortality as an outcome.

RESULTS

We found a dearth of rigorous evidence of direct impact of any of these screening procedures and interventions on stillbirth incidence. Observational studies testing some interventions, including fetal movement monitoring and Doppler monitoring, showed some evidence of impact on stillbirths in selected high-risk populations, but require larger rigourous trials to confirm impact. Other interventions, such as amniotic fluid assessment for oligohydramnios, appear predictive of stillbirth risk, but studies are lacking which assess the impact on perinatal mortality of subsequent intervention based on test findings. Few rigorous studies of cardiotocography have reported stillbirth outcomes, but steep declines in stillbirth rates have been observed in high-income settings such as the U.S., where cardiotocography is used in conjunction with Caesarean section for fetal distress.

CONCLUSION

There are numerous research gaps and large, adequately controlled trials are still needed for most of the interventions we considered. The impact of monitoring interventions on stillbirth relies on use of effective and timely intervention should problems be detected. Numerous studies indicated that positive tests were associated with increased perinatal mortality, but while some tests had good sensitivity in detecting distress, false-positive rates were high for most tests, and questions remain about optimal timing, frequency, and implications of testing. Few studies included assessments of impact of subsequent intervention needed before recommending particular monitoring strategies as a means to decrease stillbirth incidence. In high-income countries such as the US, observational evidence suggests that widespread use of cardiotocography with Caesarean section for fetal distress has led to significant declines in stillbirth rates. Efforts to increase availability of Caesarean section in low-/middle-income countries should be coupled with intrapartum monitoring technologies where resources and provider skills permit.

WITHDRAWN: Routine Doppler ultrasound in pregnancy

BACKGROUND

Doppler ultrasound study of umbilical artery waveforms helps identify the compromised fetus in 'high risk' pregnancies and, therefore, deserves assessment as a screening test in 'low risk' pregnancies. One of the main aims of routine antenatal care is to identify the 'at risk' fetus in order to apply clinical interventions which could result in reduced perinatal morbidity and mortality.

OBJECTIVES

To assess the effects on obstetric practice and pregnancy outcome of routine Doppler ultrasound in unselected and low risk pregnancies.

SEARCH STRATEGY

The Cochrane Pregnancy and Childbirth Group Specialised Register of Controlled Trials and the Cochrane Controlled Trials Register were searched. Date of last search: September 1999

SELECTION CRITERIA

Acceptably controlled trials of routine Doppler ultrasound (umbilical circulation and/or uterine circulation) in unselected or low risk pregnancies.

DATA COLLECTION AND ANALYSIS

Both reviewers assessed trial quality and extracted data. Authors of two trials were contacted for additional information.

MAIN RESULTS

Five trials were included which recruited 14,338 women. The methodological quality of the trials was generally good. Based on existing evidence, routine Doppler ultrasound examination in low risk or unselected populations did not result in increased antenatal, obstetric and neonatal interventions, and no overall differences were detected for substantive short term clinical outcomes such as perinatal mortality. There is no available evidence to assess the effect on substantive long term outcomes such as childhood neurodevelopment. There is no available evidence to assess maternal outcomes, particularly psychological effects. In two studies there were unexpected findings suggesting possible harmful effects, but the explanation for this is not clear, and further evaluation regarding the safety of Doppler ultrasound is required.

AUTHORS' CONCLUSIONS

Based on existing evidence, routine Doppler ultrasound in low risk or unselected populations does not confer benefit on mother or baby. Future research should be powerful enough to address small changes in perinatal outcome, and should include evaluation of maternal psychological effects, long term outcomes such as neurodevelopment, and issues of safety.

Management of Fetal Growth Restriction: An Evidence-Based Approach

This review provides an evidence-based approach to the management of fetal growth restriction (FGR). The management consists of the following components: appropriate fetal surveillance, timely intervention, and selective etiological management. Umbilical arterial (UA) Doppler sonography is the primary test. Supplementary tests include nonstress test (NST), amniotic fluid assessment, biophysical profile (BPP), and selective venous Doppler sonography. Ominous signs include UA absent or reverse end-diastolic flow, non-assuring NST, low BPP, and abnormal fetal venous flow patterns. An evidence-based clinical management guideline is included and individualization of care is recommended.

Normative values of Doppler velocimetry of five major fetal arteries as determined by color power angiography

OBJECTIVE

To produce normograms of Doppler indices of major fetal arteries and their ratios relative to the ascending aorta in a cohort of appropriately grown for gestational age fetuses.

METHODS

Prospective longitudinal study of 70 women with appropriately grown for gestational age fetuses between 24 and 38 weeks' gestation attending the Fetal Growth Clinic of a large UK teaching hospital. Doppler velocimetry of the middle cerebral (MCA), umbilical (UmA) and renal arteries (RA) and the ascending (AAO) and descending (DAO) aortas were studied using color power angiography. Ratios of the Doppler indices [pulsatility index (PI), resistance index (RI), systolic/diastolic (S/D) ratio] were then calculated using the ascending aorta as the reference numerator for the other four vessels to produce normograms. Regression analysis was performed to determined the significance, if any, of the changes in these ratios with gestation.

RESULTS

The normograms of the various Doppler indices were similar for the middle cerebral artery, ascending and descending aortas. There was an initial rise to a peak between 30 and 32 weeks and then a gradual return to values at 38 weeks similar to those at 24 weeks' gestation. In the renal artery, the indices showed very little variation with gestation. However, there was a gradual fall in the indices with gestation in the umbilical artery. The ratios of the various indices relative to that of the ascending aorta demonstrated an increase with gestation. The changes with gestation were statistically significant for the ratios of the indices from the ascending aorta to those of the middle cerebral, renal and umbilical arteries but not for those of the descending aorta.

CONCLUSIONS

The vascular resistance in the five fetal arteries decreased towards the end of pregnancy and the ratios of their indices relative to those of the ascending aorta decreased from 24 to 38 weeks' gestation. Early subtle changes in circulation in compromised fetuses may be identified early from deviations in these normograms.

Umbilical arterial Doppler sonography for fetal surveillance in pregnancies complicated by pregestational diabetes mellitus

Antepartum fetal surveillance constitutes an essential component of the standards of care in managing pregnancies complicated by pregestational diabetes mellitus. Fetal hyperglycemia is associated with increased oxidative metabolism, hypoxemia and increased brain and renal perfusion without any significant changes in fetoplacental perfusion. Human cordocentesis data show that fetal hypoxemia and acidemia are associated with changes in the umbilical arterial Doppler indices in maternal diabetes mellitus complicated by fetal growth restriction or pre-eclampsia. Consistent with this, observational studies suggest significant diagnostic efficacy of the Doppler method in diabetic pregnancies complicated by vasculopathy, and in the presence of fetal growth restriction or hypertension. However, the relationship between abnormal umbilical arterial Doppler indices and the quality of glycemic control remains unproved. Although there are no randomized trials specifically addressing this issue, existing evidence suggests that Doppler velocimetry of the umbilical artery may be beneficial for antepartum fetal surveillance in diabetic pregnancies complicated by vasculopathy, fetal growth restriction or hypertension.

Estimation of the Doppler ultrasound umbilical maximal waveform envelope: II. Prediction of fetal distress

Blood flow variables obtained via Doppler ultrasound (US) waveform estimation have been investigated for prediction of fetal distress. The umbilical flow was assessed using a number of waveform summary statistics in addition to the currently used resistance indices. We examined the relationship between umbilical artery waveform patterns and intrauterine growth restriction, preterm delivery and hypertensive disorders. To enhance prediction, we defined waveform skewness profiles based on pivotal points of the umbilical waveform that appeared to be related to the incidence of preterm delivery and that facilitated construction of IUGR prediction models. The data comprised 204 unselected pregnancies with the umbilical artery images recorded at 18 pregnancy weeks. The sample was divided into 114 pregnancies used to estimate model parameters and 90 pregnancies to validate the model. Logistic prediction models for detection of abnormal velocity waveforms associated with intrauterine growth restriction were derived, based on the waveform information. The estimated model sensitivity and specificity on the training data were 74% and 84%, respectively. Validation of the model on independent data yielded a sensitivity of 57% and specificity of 84%. The logistic IUGR prediction model appears to have significant predictive ability and potential for clinical use, even at this early gestational age. Our data suggest that prediction of IUGR at 18 pregnancy weeks can be much improved when the waveform shape is captured with a number of summary statistics in addition to resistance indices.

Fetal cerebral blood flow redistribution in late gestation: identification of compromise in small fetuses with normal umbilical artery Doppler

OBJECTIVE

To evaluate the role of middle cerebral artery Doppler in small fetuses during the late third trimester.

DESIGN

Prospective observational study of structurally normal fetuses with an estimated fetal weight < 5th percentile for gestation. Perinatal outcome was determined using a structured datasheet sent to each referring obstetrician.

SUBJECTS

Structurally normal fetuses at 35 or more weeks of gestation referred during a 2-year period to the fetal growth clinic of a regional fetal medicine unit in North London. Fetuses with aneuploidy and/or major structural abnormalities were excluded.

METHODS

Umbilical artery and middle cerebral artery (MCA) Doppler waveforms were recorded and considered abnormal if above 95th or below 5th percentiles, respectively. Amniotic fluid was considered reduced if the maximum vertical cord-free pool was < 2 cm. The placenta was considered mature if the Grannum grade was II or III. The head circumference (HC)/abdominal circumference (AC) ratio was considered abnormal if > 95th percentile for gestation. Fetal growth, amniotic fluid, biophysical profile score and umbilical artery Doppler were used to advise the referring obstetrician about fetal well-being and he/she independently decided both the timing and mode of delivery.

RESULTS

Forty-seven fetuses fulfilled the entry criteria. Thirty-four (72%) demonstrated normal umbilical artery Doppler waveforms. Sixteen (34%) demonstrated middle cerebral artery redistribution, of which nine (56%) had normal umbilical artery Doppler waveforms. MCA blood flow redistribution was associated with an increased incidence of cesarean delivery and need for neonatal admission. Of all gray-scale parameters, an elevated HC/AC ratio has the strongest association with MCA blood flow redistribution (15/16 vs. 1/31; P < 0.01).

CONCLUSIONS

MCA Doppler may be a useful tool to assess the health of small fetuses in the late third trimester. Redistribution may occur in the presence of normal umbilical artery Doppler and should be suspected when the HC/AC ratio is elevated.

Routine doppler ultrasound in pregnancy

BACKGROUND

Doppler ultrasound study of umbilical artery waveforms helps identify the compromised fetus in 'high risk' pregnancies and, therefore, deserves assessment as a screening test in 'low risk' pregnancies. One of the main aims of routine antenatal care is to identify the 'at risk' fetus in order to apply clinical interventions which could result in reduced perinatal morbidity and mortality.

OBJECTIVES

To assess the effects on obstetric practice and pregnancy outcome of routine Doppler ultrasound in unselected and low risk pregnancies.

SEARCH STRATEGY

The Cochrane Pregnancy and Childbirth Group Specialised Register of Controlled Trials and the Cochrane Controlled Trials Register were searched. Date of last search: September 1999

SELECTION CRITERIA

Acceptably controlled trials of routine Doppler ultrasound (umbilical circulation and/or uterine circulation) in unselected or low risk pregnancies.

DATA COLLECTION AND ANALYSIS

Both reviewers assessed trial quality and extracted data. Authors of two trials were contacted for additional information.

MAIN RESULTS

Five trials were included which recruited 14,338 women. The methodological quality of the trials was generally good. Based on existing evidence, routine Doppler ultrasound examination in low risk or unselected populations did not result in increased antenatal, obstetric and neonatal interventions, and no overall differences were detected for substantive short term clinical outcomes such as perinatal mortality. There is no available evidence to assess the effect on substantive long term outcomes such as childhood neurodevelopment. There is no available evidence to assess maternal outcomes, particularly psychological effects. In two studies there were unexpected findings suggesting possible harmful effects, but the explanation for this is not clear, and further evaluation regarding the safety of Doppler ultrasound is required.

REVIEWER'S CONCLUSIONS

Based on existing evidence, routine Doppler ultrasound in low risk or unselected populations does not confer benefit on mother or baby. Future research should be powerful enough to address small changes in perinatal outcome, and should include evaluation of maternal psychological effects, long term outcomes such as neurodevelopment, and issues of safety.

Doppler ultrasound for fetal assessment in high risk pregnancies

BACKGROUND

Abnormal waveforms from Doppler ultrasound may indicate poor fetal prognosis. It is also possible that Doppler ultrasound could encourage inappropriate early delivery.

OBJECTIVES

The objective of this review was to assess the effects of Doppler ultrasound in high risk pregnancies on obstetric care and fetal outcomes.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group trials register.

SELECTION CRITERIA

Randomised trials of Doppler ultrasound for the investigation of umbilical artery waveforms in high risk pregnancies compared to no Doppler ultrasound.

DATA COLLECTION AND ANALYSIS

Trial quality was assessed and data were extracted by both reviewers. Study authors were contacted for additional information.

MAIN RESULTS

Eleven studies involving nearly 7000 women were included. The trials were generally of good quality. Compared to no Doppler ultrasound, Doppler ultrasound in high risk pregnancy (especially those complicated by hypertension or presumed impaired fetal growth) was associated with a trend to a reduction in perinatal deaths (odds ratio 0.71, 95% confidence interval 0.50 to 1.01). The use of Doppler ultrasound was also associated with fewer inductions of labour (odds ratio 0.83, 95% confidence interval 0.74 to 0.93) and fewer admissions to hospital (odds ratio 0.56, 95% 0.43 to 0.72), without reports of adverse effects. No difference was found for fetal distress in labour (odds ratio 0.81, 95% confidence interval 0.59 to 1.13) or caesarean delivery (odds ratio 0.94, 95% 0.82 to 1.06).

REVIEWER'S CONCLUSIONS

The use of Doppler ultrasound in high risk pregnancies appears to improve a number of obstetric care outcomes and appears promising in helping to reducing perinatal deaths.

Intrapartum umbilical artery Doppler velocimetry as a predictor of adverse perinatal outcome: a systematic review

OBJECTIVE

To evaluate the diagnostic prediction of intrapartum umbilical artery Doppler velocimetry for adverse perinatal outcomes using systematic quantitative overview of the available literature.

DESIGN

Online searching of MEDLINE database (January 1966-September 1997), scanning of bibliography of known primary and review articles, review of recent journal issues and that from personal files. Study selection, assessment of study quality and data extraction were all performed in duplicate under masked conditions.

PARTICIPANTS

2700 women (unselected, low, high, and combined low and high obstetric risk populations) included in eight studies selected for meta-analyses.

MAIN OUTCOME MEASURES

Likelihood ratios (LRs) for positive and negative test results were generated for the following outcome measures: Apgar scores < 7 at 1 and 5 minute following delivery, small for gestational age fetus; intrapartum fetal heart rate abnormality, umbilical arterial acidosis at delivery; and caesarean section for fetal distress.

RESULTS

For Apgar score < 7 at 1 minute following delivery, the pooled LR was 2.5 (95% CI 1.7-3.7) for a positive test and 1.0 (95% CI 0.9-1.1) for a negative test result. A positive test predicted an Apgar score < 7 at 5 minute following delivery with a pooled LR of 1.3 (95% CI 0.4-4.1) while a negative test had a pooled LR of 1.0 (95% CI 0.8-1.2). For the prediction of a small for gestational age fetus, the pooled LR was 3.4 (95% CI 2.3-5.1) for a positive test and 0.9 (95% CI 0.8-1.0) for a negative test. The prediction for fetal heart rate abnormality during labour was similarly disappointing: the pooled LR for a positive test result was 1.4 (95% CI 0.9-1.2) whereas a negative test result generated a pooled LR of 0.9 (95% CI 0.9-1.0). With umbilical acidosis at delivery, the pooled LR was 1.6 (95% CI 1.1-2.5) for a positive test and 1.1 (95% CI 1.0-1.2) for a negative test. The LRs for the prediction of caesarean section for fetal distress were 4.1 (95% CI 2.7-6.2) for a positive test result and 0.9 (95% CI 0.8-1.0) for a negative test result.

CONCLUSION

Intrapartum umbilical artery Doppler velocimetry is a poor predictor of adverse perinatal outcomes.

Fetal heart rate (FHR) pathology in labor related to preceeding Doppler sonographic results of the umbilical artery and fetal aorta in appropriate and small for gestational age babies. A longitudinal analysis

The aim of this study was to ascertain the value of serially performed Doppler sonographic measurements of fetal vessels for the prediction of FHR alterations in labor a longitudinal analysis was conducted. 24 patients with SGA fetuses as the only risk factor and 38 patients without any risk factor were recruited for the study. Flow velocity waveforms of the fetal aorta and the umbilical artery were analyzed for systolic diastolic (S/D) ratio weekly at 20-39 weeks gestation and from 30 weeks gestation onwards twice weekly. Courses were related to complications during labor reflected by alterations of FHR tracings. The more numerous pathologie S/D ratios of both fetal vessels were recorded the more frequently complications in labor occurred (Chi Square test, p < 0.05). The mean value of the S/D ratios in fetuses with FHR pathology in labor differed significantly compared to the uncomplicated group (Wilcoxon rank sum test, p < 0.05). The fluctuation of S/D ratios was greater in the complicated than in the normal group (Wilcoxon rank sum test, p < 0.05). A combination of parameters describing S/D ratios showed a sensitivity of 86% and a specificity of 19% for the fetal aorta and a sensitivity of 71% and a specificity of 91% for the umbilical artery. Serial Doppler measurements of the fetal aorta and the umbilical artery aid in predicting pathologic FHR alterations in labor and may be of benefit in antenatal care to ensure fetal well being particularly in cases of IUGR.

A randomised controlled trial of Doppler ultrasound velocimetry of the umbilical artery in low risk pregnancies. Doppler French Study Group

OBJECTIVE

To evaluate the effect on management and outcome of pregnancy of routine umbilical Doppler examination in low risk populations.

DESIGN

Pragmatic randomised controlled trial.

SETTING

Twenty centres caring for low risk pregnant women.

PARTICIPANTS

4187 women were randomly assigned to umbilical Doppler between 28 and 34 weeks of gestation or no routine umbilical Doppler. The women included were at low risk at 28 weeks of gestation defined by a normal ultrasonographic examination at the time of randomisation and no obstetric or medical complications during the first two trimesters of the pregnancy.

RESULTS

The general characteristics at inclusion were comparable for the two groups. Performance of umbilical Doppler led to a significant increase in the number of ultrasonographic and Doppler examinations subsequently conducted; there were no other effects on the management of the pregnancy. There was no significant difference in fetal distress during labour (odds ratio [OR] 0.96; 95% confidence interval [CI] 0.70-1.33). There were three times fewer perinatal deaths in the Doppler group (three versus nine), but this difference was not significant (OR 0.33; 95% CI 0.06-1.33).

CONCLUSION

Based on this trial routine use of umbilical doppler for low risk pregnancy cannot be recommended. More data are needed to reach a definite conclusion of the value of routine Doppler.

Umbilical artery Doppler velocimetry in unselected and low risk pregnancies: a review of randomised controlled trials

OBJECTIVE

Meta-analysis of data from controlled trials performed in populations at high risk have shown that umbilical artery Doppler velocimetry (umbilical Doppler) can reduce perinatal mortality. The individual published trials among unselected or low risk populations have found no beneficial effect. Our objective was to evaluate the effect of routine use of the umbilical Doppler in unselected or low risk pregnancies by reviewing all published and unpublished randomised controlled trials.

STUDY DESIGN

Systematically reviewing published and unpublished trials, we selected trials for the overview only if they were completed randomised trials of umbilical Doppler in unselected or low risk pregnancies. Of the seven trials examined, three were not included in the meta-analysis because of methodological problems or because they did not meet the inclusion criteria. We therefore included four trials: two in unselected and two in low risk populations. These four groups were comparable in their degree of maternal and perinatal risk. Using the Mantel-Haenzel statistical method and pooling the data, we considered 11,375 women in the meta-analysis.

RESULTS

Systematic use of the Doppler umbilical artery velocimetry had no statistically significant effect on perinatal deaths in unselected populations (odds ratio [OR] 1.28; 95% confidence interval [CI] 0.61-2.67), low risk populations (OR 0.51; 95% CI 0.20-1.29) or overall for the four trials (OR 0.90; 95% CI 0.50-1.60); nor was there any significant effect on stillbirths (global OR 0.94; 95% CI 0.42-1.98). However, the number of participants remain insufficient and further information is required to arrive at a definite conclusion on the absence of effect. The meta-analysis showed no significant difference between the Doppler groups and the control groups for antenatal hospitalisation, obstetric outcome or perinatal morbidity.

CONCLUSION

Based on the results of the published trials, routine use of the umbilical Doppler cannot be recommended.

Predictive value of Doppler umbilical artery velocimetry in a low risk population with normal fetal biometry. A prospective study of 2016 women

OBJECTIVE

To assess the predictive value of Doppler umbilical artery velocimetry in a low-risk population with normal fetal biometry.

STUDY DESIGN

Multicenter prospective study in 17 hospitals with prenatal clinics in France. Two thousand sixteen women who, before 28 weeks gestation were defined as at low risk after routine consultation and after ultrasound. Doppler umbilical artery velocimetry was performed between 28 and 34 weeks gestation. Confounding factors were used to perform multivariate regression.

RESULTS

1903 cases were analysed and 192 (10.1%) had an abnormal Doppler Resistance Index (RI). The abnormal Doppler group contained a significantly higher frequency of severe and moderate small for gestational age infants (SGA), both severe and moderate with a sensitivity of 25.5 and 18.8% respectively. There was no difference in hypertensive disorders or criteria of fetal distress. Mean birth weight was very significantly lower in the abnormal group (162 g). Birth weight was very significantly linked to RI after taking into account confounding variables in the multiple linear regression model (continuous relationship). After multiple logistic regression, the odds ratio associated with an abnormal Doppler result, adjusted for all the confounding factors, was 2.3 (95% CI 1.5-3.7) for moderate SGA and 3.5 (95% CI of 1.8-7.1) for severe SGA.

CONCLUSION

Low umbilical Doppler RI is predictive with moderate or severe SGA in a low-risk population with normal fetal biometry, even when the information generally available in clinical practice and ultrasound parameters are taken into account. There is a continuous relationship between RI and birthweight. This predictive value cannot, however, lead to an improvement in neonatal health unless effective measures to prevent SGA exist and umbilical Doppler should not be used in low-risk population on a routine basis.

Umbilical artery Doppler velocimetry: clinical utility in high-risk pregnancies

An abnormal result of an umbilical artery Doppler study reflects the presence of placental vascular pathologic mechanisms and identifies pregnancies at increased risk for perinatal mortality. Recent reviews of the clinical utility of umbilical artery Doppler study have concluded that it should not be routinely used as a screening modality for the general obstetric population and have suggested that further research is required. However, metaanalysis of published peer-reviewed and randomized controlled trials indicates that its use in high-risk pregnancies is associated with a significant decrease in perinatal mortality without an increase in the rate of inappropriate obstetric intervention. This clinical opinion serves to underscore the relevance of umbilical artery Doppler velocimetry to clinical practice and to suggest that an abnormal result of an umbilical artery Doppler study should be added to the current list of indications for intensive fetal surveillance.

Recent advances. Obstetrics

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Doppler ultrasonography in high-risk pregnancies: systematic review with meta-analysis

OBJECTIVE

Our objective was to review all available (published and unpublished) randomized controlled trials of Doppler ultrasonography of the umbilical artery in high-risk pregnancies.

STUDY DESIGN

Only completed randomized controlled trials were included and reviewed according to the prespecified protocol. Data were sought for 24 prespecified perinatal outcomes. All meta-analyses were based on the "intention to treat." Primary outcome was defined as perinatal death (any death in utero or postnatally recorded during duration of individual randomized controlled trial). Reported perinatal outcomes that were not prespecified were meta-analyzed on a post hoc basis.

RESULTS

Twenty randomized controlled trials of Doppler ultrasonography were identified; 12 fulfilled the prespecified criteria. Meta-analysis shows a significant reduction in the number of antenatal admissions (44%, 95% confidence interval 28% to 57%), inductions of labor (20%, 95% confidence interval 10% to 28%), and cesarean sections for fetal distress (52%, 95% confidence interval 24% to 69%) in the Doppler group and that the clinical action guided by Doppler ultrasonography reduces the odds of perinatal death by 38% (95% confidence interval 15% to 55%). The reduction in perinatal deaths was also observed in five mortality subgroups (i.e., stillbirths, neonatal deaths, deaths of normally formed babies, normally formed stillbirths, and deaths of normally formed neonates). Post hoc analyses revealed a statistically significant reduction in elective delivery, intrapartum fetal distress, and hypoxic encephalopathy in the Doppler group.

CONCLUSION

There is now compelling evidence that women with high-risk pregnancies, including preeclampsia and suspected intrauterine growth retardation, should have access to Doppler ultrasonographic study of umbilical artery waveforms.