The accuracy of ultrasound scan in diagnosing retained products of conception: a systematic review and meta-analysis

This study aimed to analyze and summarize the evidence on the accuracy of different ultrasound methods in the diagnosis of retained products of conception. We searched Ovid SP, the Cumulative Register to Nursing & Allied Health Literature, EBSCO, and grey literature including Core, Trip, Networked Digital Library of Theses and Dissertations Global ETD search, BMJ Best Practice, PubMed, GreyLit report website (http://www.greylit.org/), Cochrane Central Register of Controlled Trials, and Google scholar (https://scholar.google.com/). We included prospective and retrospective cross-sectional or Cohort studies that evaluated both ultrasound findings (before management of retained products of conception) and histopathologic results of retained products of conception at all gestational ages. We used Covidence for data extraction from the studies and quality assessment. The meta-analysis was performed using RevMan 5.4 (forest plot), MetaDTA version 2.01, and Meta-DiSc 2.0 online software. In total, 11 studies were eligible for data extraction and meta-analysis. The total number of study participants from these 11 studies were 1567. Of these, 9 studies were included to test the accuracy of an echogenic mass, 4 studies analyzed the accuracy of endometrial thickness, and 5 studies analyzed the accuracy of color Doppler flow to predict retained products of conception. We found that echogenic mass had the highest sensitivity, specificity, and diagnostic odds ratio for predicting retained products of conception. The sensitivity, specificity, and diagnostic odds ratio were 0.915 (95% confidence interval, 0.844–0.955), 0.843 (95% confidence interval, 0.615–0.947), and 57.787 (95% confidence interval, 15.171–220.112), respectively. The diagnostic threshold for endometrial thickness was set at 10 mm with a sensitivity, specificity, and diagnostic odds ratio of 0.667 (95% confidence interval, 0.072–0.981), 0.866 (95% confidence interval, 0.375–0.986), and 12.927 (95% confidence interval, 0.23–726.582). The sensitivity, specificity, and diagnostic odds ratio of color Doppler flow were 0.850 (95% confidence interval, 0.756–0.913), 0.406 (95% confidence interval, 0.198–0.655), and 3.893 (95% confidence interval, 1.005–15.081). Our review concluded that an echogenic mass is the most sensitive and specific predictor of retained products of conception after any pregnancy event. The most important limitation of our review is that the design of the studies included led to significan