Study designs of evaluations included in the review
No inclusion criteria relating to study design were reported.
Specific interventions included in the review
Studies of foetal echocardiography were eligible for inclusion. Only studies in which all patients received foetal echocardiography were eligible for inclusion. Studies that did not fully describe the ultrasound technique (scanning regime, gestation at scanning and equipment used) were excluded. The included studies assessed:
routine foetal echocardiography (four-chamber view + outflow tracts),
routine followed by extended foetal echocardiography on suspicion of congenital heart disease (four-chamber view + outflow tracts + Doppler colour-flow mapping in selected patients), or
routine extended foetal echocardiography (four-chamber view + outflow tracts + Doppler colour-flow mapping).
Ultrasound operators in the included studies included experienced trained specialists, experienced trained non-specialists, and experienced and inexperienced non-trained non-specialists. The ultrasound transducer frequency ranged from 3.5 to 5 MHz.
Reference standard test against which the new test was compared
Studies that included a postnatal reference standard were eligible for inclusion. The reference standards reported in the included studies were neonatal examination, neonatal echocardiography, autopsy, and electrocardiogram at birth and at 6 and 24 months' follow-up.
Participants included in the review
Studies of low-risk women in their second trimester, or in general unselected obstetric populations of second trimester women, were eligible for inclusion. Studies restricted to high-risk pregnant women were excluded. Gestation at scanning ranged from 20 to 34 weeks.
Outcomes assessed in the review
The studies had to report sufficient data to construct a 2x2 table of test performance to be included in the review. Estimates of accuracy were presented separately for major defects, minor defects, non-structural defects or arrhythmias, and all defects.
How were decisions on the relevance of primary studies made?
The authors did not state how the papers were selected for the review, or how many reviewers performed the selection.