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

Objective: 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.

Methods: 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.

Results: 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.

Conclusions: 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.