Screening of fetal congenital heart disease: the challenge continues

Abstract

Congenital heart disease (CHD) is the most common congenital malformation [1] in fetuses. It affects eight per 1,000 live births and is more common antenatally [2-5]. In beginning, cardiac evaluation was confined to pregnancies at increased risk of CHD, such as those with a family history of CHD or where extracardiac malformations had been detected. However, up to 86% of CHD occurs in pregnancies where there are no known high risk features [6], emphasizing the need for an effective fetal cardiac screening program for all pregnancies [7,8]. For this reason, in the mid 80’s started the idea of teaching the obstetrician to assess the heart in a simplified form during routine obstetric scanning [9,10]. Four chamber view scanning became an integral part of the fetal anatomical survey in many countries by the end of the 1980s [9,10]. However, prenatal screening based on visualization of the four-chamber view has much lower sensitivity [6,11]. This is partly because the four-chamber view may appear normal in cases of many anomalies, such as transposition of the great vessels, tetralogy of Fallot, double outlet right ventricle, truncus arteriosus, pulmonary or aortic stenosis/atresia and coarctation of the aorta. Anomalies of the great vessels are associated with an abnormal four-chamber view in 30% of cases [12]. When four-chamber and great vessels view are examined, the sensitivity of ultrasound screening for congenital heart defects increases from approximately 30% to 69–83% [6,11,13]. Therefore, we support the idea of evaluation both the four-chamber view and the outflow tracts (Figure 1). Then, we could improve the rate of prenatal detection of congenital heart disease. In 2006, the International Society of Ultrasound in Obstetrics and Gynecology (ISUOG) published a guideline in which they described the “basic” and “extended basic” cardiac ultrasound examinations [14]. The intention was to standardize the assessment and to maximize the detection of heart anomalies during the second-trimester scan (Figure 1). However, we agree that a comprehensive fetal echocardiography should be performed when heart anomalies are suspected. One of the problems to follow this guideline is the difficulty of obtaining images of the outflow tracts. This happens because unlike the four-chamber view, the aorta and pulmonary artery do not lie in a single axis. In