ISUOG consensus statement: what constitutes a fetal echocardiogram?

In 2006 the International Society of Ultrasound in Obstetrics and Gynecology (ISUOG) published practice guidelines for the sonographic screening of congenital heart disease (CHD) during the second trimester of pregnancy1. This document described two levels for screening low-risk fetuses for heart anomalies. Firstly, a ‘basic’ scan should be performed by analyzing a four-chamber view of the fetal heart. Secondly, an ‘extended-basic’ scan further examines the size and relationships of both arterial outflow tracts. The term ‘fetal echocardiogram’ was also mentioned as a more detailed sonographic evaluation to be performed by specialists in the prenatal diagnosis of CHD. Although common indications and imaging techniques were briefly discussed, it was thought important to further explain how this advanced diagnostic procedure differs from the basic and extended-basic cardiac screening examinations. A Fetal Echocardiography Task Force was subsequently asked to develop a standard description of ‘what constitutes a fetal echocardiogram’. Our original goal was to develop guidelines for a detailed examination of the fetal heart that were based on the literature and a consensus opinion of an expert panel. However, we soon realized that this project was quite different from developing minimum practice guidelines for fetal cardiac screening. There are several imaging modalities that can be used to evaluate fetal heart anomalies, ranging from M-mode techniques and color Doppler sonography to the use of four-dimensional (4D) ultrasonography with spatiotemporal image correlation (STIC). Consequently, our original efforts to develop a minimum practice guideline for fetal echocardiography evolved into a consensus statement that covers the following topics: