Cochrane systematic review and meta-analysis of first- and second-trimester ultrasound screening for fetal anomalies in low-risk pregnancies

To evaluate the diagnostic accuracy of first- and second-trimester ultrasound screening for fetal structural anomalies in low-risk pregnancies. To determine the accuracy of ultrasound in detecting anomalies before 14 weeks of gestation by a single first trimester scan (s-FTS), and before 24 weeks of gestation by a single second-trimester scan (s-STS) or by a first- and second-trimester scan (F+STS) combined and compare the effectiveness of both screening strategies. We performed a systematic review and meta-analysis. We searched MEDLINE, Embase and Web of Science from January 1997 to July 2022. Two review authors independently carried out study selection, data extraction and quality assessment. We included 86 studies (7,054,855 fetuses, 25,176 anomalies). The summary sensitivity of s-FTS was 37.5% (95% CI: 31.1-44.3) and of s-STS was 50.5% (95% CI: 38.5 to 62.4). The combined sensitivity of F+STS was 83.8% (95% CI: 74.7-90.1), F+STS screening had a significantly higher sensitivity than s-STS (P < 0.001) (figure 1A). Gross structural anomalies, such as anencephaly and abdominal wall defects, accounted for a higher proportion of cases in the s-FTS and F+STS studies (figure 1B). There is a remarkable difference in the sensitivity of fetal anomaly screening by F+STS, compared to s-STS. This result may reflect a difference in the spectrum of anomalies present at the time of screening, rather than a true difference in sensitivity. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.