Operator experience impact on the evaluation of still images of a first trimester cardiac assessment protocol

Congenital heart disease (CHD) is the most common birth defect and represents the leading cause for mortality and morbidity in infants and young adults. Early fetal echocardiography is usually considered a highly specialized scan. The goal of this study is to evaluate the impact of operator's experience in assessing still images of the 4-chamber view and 3-vessels view and to evaluate the feasibility and the performance of a first trimester screening protocol for CHD.

An online questionnaire consisting of still images of the 4-camber view and 3-vessel view from 50 normal and abnormal cases was reviewed by an expert group made of seven obstetricians specialized in fetal medicine and a nonexpert group made of 13 obstetricians that are certified in ultrasound. After individually visualizing each image set made of the 4-chamber view and 3-vessel view, they had to conclude if the case was normal or abnormal and what images were abnormal.

A total of 50 image sets of both normal and abnormal fetal hearts were examined by the 20 reviewers, resulting in 1000 evaluations. The expert group achieved a detection rate of 97.1% with a false positive rate of 5.7%. The nonexpert group achieved also a good detection rate of 91.3% but with a much higher false positive rate of 33.9%. The most frequently missed CHD involved the great arteries and had a normal 4-chamber view. In the majority of false positive cases the 3-vessel view was incorrectly interpreted as abnormal.

A screening protocol for CHD, based on the 4-chamber view and 3-vessel view alone can offer a good detection rate for CHD with a small false positive rate, but only if it is implemented by highly specialized sonographers.