Prevalence of abnormal umbilical arterial flow on Doppler ultrasound in low-risk and unselected pregnant women: a systematic review

Abstract

Background While Doppler ultrasound screening is beneficial for women with high-risk pregnancies, there is insufficient evidence on its benefits and harms in low- and unselected-risk pregnancies. This may be related to fewer events of abnormal Doppler flow, however the prevalence of absent or reversed end diastolic flow (AEDF or REDF) in such women is unknown. In this systematic review, we aimed to synthesise available data on the prevalence of AEDF or REDF. Methods We searched PubMed, Embase, CINAHL, CENTRAL and Global Index Medicus with no date, setting or language restrictions. All randomized or non-randomized studies reporting AEDF or REDF prevalence based on Doppler assessment of umbilical arterial flow > 20 weeks’ gestation were eligible. Two authors assessed eligibility and extracted data on primary (AEDF and REDF) and secondary (fetal, perinatal, and neonatal mortality, caesarean section) outcomes, with results presented descriptively. Results A total of 42 studies (18,282 women) were included. Thirty-six studies reported zero AEDF or REDF cases. However, 55 AEDF or REDF cases were identified from just six studies (prevalence 0.08% to 2.13%). Four of these studies were in unselected-risk women and five were conducted in high-income countries. There was limited evidence from low- and middle-income countries. Conclusions Evidence from largely observational studies in higher-income countries suggests that AEDF and REDF are rare among low- and unselected-risk pregnant women. There are insufficient data from lower-income countries and further research is required.

Middle cerebral arterial flow redistribution is an indicator for intrauterine fetal compromise in late pregnancy in low‐resource settings: A prospective cohort study

“…The results are comparable with the prevalence of AEDF or REDF (0%-2.13%) reported in low-risk pregnancies in HICs. 17 Interestingly, a study from South Africa reported a prevalence of abnormal UA resistive index (RI) (and AREDF) in low-risk pregnancies of 13.0% (1.2%). 32 The large difference with our observations could be explained by the classical differences in the pathophysiology of early and late FGR: Hlongwane et al 32 enrolled women at 28-34 weeks of gestation, a period in which abnormal UA commonly manifests.…”

“…This is of relevance to LMIC settings where stillbirths are ten times more common than in HICs 1 . It should also be noted that, because of a lack of studies, a recent systematic review was unable to establish the prevalence in LMIC settings of absent or reversed end‐diastolic flow (AEDF or REDF) in the umbilical artery (UA) among low‐risk pregnancies or women undergoing routine ANC 17 . The finding was rare (0%–2%) in HICs 17 .…”

Late pregnancy ultrasound parameters identifying fetuses at risk of adverse perinatal outcomes: a protocol for a systematic review of systematic reviews

“…This paper presents a protocol for a systematic review of systematic reviews of key obstetric ultrasound parameters to identify pregnancies at risk of adverse perinatal outcomes at or close to term. It will use rigorous methodology based on current guidelines,16–19 21 23–25 and to the best of our knowledge, this is the first systematic overview of systematic reviews in this area. Adverse perinatal outcomes remain a critical contributor to under-5 year mortality and lifelong neurodevelopmental complications 1 2.…”

“…In the absence of high-Grading of Recommendations Assessment, Development and Evaluation (GRADE) criteria,11 evidence on universal obstetric ultrasound screening at or close to term to prevent adverse outcomes, many different screening strategies have been proposed. Similarly, due to the diverse nature of ultrasound parameters and the wide range of possible adverse perinatal outcomes,12 the last decade has witnessed a rapid proliferation of systematic reviews in this area 13–18. Therefore, clinicians and policy-makers are overwhelmed by the current pace of evidence 19.…”

Identifying the High-Risk Fetus in the Low-Risk Mother Using Fetal Doppler Screening

“…Until recently, the prevalence of AEDF and abnormal RIs had not been determined ( Table ). 28 Nkosi et al used CWDU in a sample of 2,868 LRMs in a township in South Africa (an LMIC setting) undergoing a single CWDU screening between 28 and 32 weeks of gestation and found a prevalence of 1.5% for AEDF and 11.7% for abnormal UmA-RI. 21 Hlongwane et al screened 7,088 LRMs with CWDU between 28 and 34 weeks of gestation in 9 different sites across 8 provinces in South Africa 29 and found a similarly high prevalence of abnormal UmA-RI (13%) and AEDF (1.2%).…”