Ten studies (1,243 mothers) were included.
Eight studies assessed a high-risk population. Eight studies used a prospective design of which seven enrolled consecutive patients. Only 4 studies used an appropriate reference standard (postnatal or postmortem assessment). No studies reported blinding. Nine studies verified the diagnosis in over 90% of foetuses.
Transabdominal ultrasound (4 studies).
Sensitivity was 25% in 1 study and 100% in 2 studies; it could not be calculated in the remaining study as no CHD was detected. Specificity was 100% in all studies.
Transvaginal ultrasound (4 studies).
The sensitivity ranged from 33 to 86% and the specificity from 96 to 100%,; there was no statistical evidence of heterogeneity (p=0.347 and p=0.120, respectively). The pooled sensitivity was 62% (95% CI: 44, 78) and the pooled specificity was 99% (95% CI: 98, 100).
Transabdominal and transvaginal ultrasound combined (2 studies).
The sensitivity was 78% in 1 study and 89% in the other. Specificity was 100% in both studies.