Predictive accuracy of second-trimester uterine artery Doppler indices for stillbirth: A systematic review and meta-analysis

Objective To assess the predictive accuracy for stillbirth of second-trimester uterine artery Doppler. Methods We searched MEDLINE, EMBASE and The Cochrane Library databases from inception until March 2015 without language restrictions. The included studies were those that assessed the association of abnormal uterine artery Doppler parameters and stillbirth. Two independent reviewers selected the studies, extracted data and assessed quality. Results for studies that were performed in the second trimester were pooled and summary estimates of sensitivity, specificity, likelihood ratios and their 95% confidence intervals were obtained. An overall summary of test accuracy was provided by the diagnostic odds ratio. Subgroup analysis was performed according to whether the study population was high risk or unselected. Results Literature searches returned 338 relevant citations with 32 considered in full. Thirteen studies met our search criteria (85 845 women, 508 stillbirths) and were included in the review. Bivariate pooled estimate for sensitivity was 65% (95% CI, 38-85%) and for specificity 82% (95% CI, 72-88%). The positive likelihood ratio was 3.5 (95% CI, 2.3-5.5) and negative likelihood ratio 0.43 (95% CI, 0.22-0.85). The diagnostic odds ratio was 8.3 (95% CI, 3.0-22.4). Heterogeneity was high in the studies of high-risk women. Conclusions Abnormal uterine artery Doppler indices are associated with a three- to four-fold increase in the risk of stillbirth. The heterogeneity was particularly high in the high-risk group rendering it impossible to draw firm conclusions. In view of this, there is a role for individual patient data meta-analysis to define which Doppler parameter and threshold value should be measured.