First trimester ultrasound for the detection of fetal heart anomalies: A systematic review and meta-analysis.
Karim JN., Bradburn E., Roberts N., Papageorghiou AT., ACCEPTS study None.
OBJECTIVES: To determine the diagnostic accuracy of ultrasound at 11-14 weeks gestational age in the detection of fetal cardiac abnormalities, and to evaluate factors that impact detection rates. METHODS: A systematic review of studies evaluating the diagnostic accuracy of ultrasound in the detection of fetal cardiac anomalies at 11-14 weeks gestational age was undertaken by two independent reviewers. Prospective and retrospective studies evaluating pregnancies at all levels of prior risk and in any healthcare setting were eligible for inclusion. The reference standard used was the detection of a major cardiac abnormality on postnatal or post-mortem examination. Data were extracted from included studies to populate 2 x 2 tables. Meta-analysis was performed using a random-effects model in order to determine the overall performance of first trimester ultrasound in the detection of major cardiac abnormalities overall and in addition, for individual types of cardiac abnormalities. Data were analysed separately for high-risk populations vs. non-high risk populations. Pre-planned secondary analyses were conducted in order to assess factors which may impact screening performance including: the imaging protocol used for cardiac assessment (including use of Colour Doppler), mode of ultrasound, publication year of study, and the index of sonographer suspicion at the time of scan. A risk of bias and quality assessment was undertaken for all included studies using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2). RESULTS: An electronic search of four databases (Medline, Embase, Web of Science Core Collection and Cochrane Library) was conducted from January 1998 until July 2020 and identified 4108 citations. This led to 223 full text reviews from which a total of 63 studies were selected for inclusion. Data from a total of 328,214 screened fetuses were included. In non-high risk populations (45 studies, 306,872 fetuses), 1,445 major cardiac anomalies were identified (prevalence 0.41 (95% C.I. 0.39 - 0.43)). Of these, 767 were correctly detected by first trimester examination of the heart and 678 were not detected. Pooled sensitivity was 55.80% (95% CI 45.87- 65.50%,), specificity 99.98% (95% CI 99.97 - 99.99%) and positive predictive value 94.85% (95% CI 91.63- 97.32%). The cases diagnosed in the first trimester represent 63.67% (95% CI 54.35 - 72.49%) of all antenatally diagnosed major cardiac abnormalities. In high risk populations (18 studies, 21,342 fetuses) 480 major cardiac anomalies were identified (prevalence 1.36 (95% C.I. 1.20 - 1.52)). Of these, 338 were correctly detected in the first trimester, and 142 were not detected. The sensitivity was 67.74% (95% CI 55.25 - 79.06%), specificity 99.75% (95% CI 99.47 - 99.92%) and positive predictive value 94.22% (95% CI 90.22 - 97.22%). The cases diagnosed in the first trimester represent 79.86% (95% CI 69.89 - 88.25%) of all antenatally diagnosed major cardiac abnormalities in high risk populations. The imaging protocol used for examination was found to have an important impact on screening performance in all populations (p<0.0001), with significantly higher detection rates in those studies using outflow tract views and colour-flow Doppler imaging (both p<0.0001). Results showed that individual cardiac anomalies are not equally amenable to first trimester detection. CONCLUSIONS: First trimester examination of the heart allows identification of over half of fetuses who are highly likely to be affected by major cardiac pathology. Future first-trimester screening programmes should follow structured anatomical assessment protocols, and introduction of outflow tract views and colour Doppler would be expected to improve detection rates. This article is protected by copyright. All rights reserved.