ABSTRACT
The examination duration is much longer in multiple pregnancy than the average 45 min required for a scan in singletons; more important, however, is the timing of the scan. In the first trimester when the size of the heart is 4-6 mm, fetal echocardiography can be misleading with respect to the intrinsic morphology (Figure 42.1). The optimal gestational age for fetal echocardiography is approximately 20 weeks, when the size of the heart is about 20 mm and large enough for clear and detailed visualization using a transabdominal
approach (Figure 42.2), and, moreover, at this stage cardiac size should be similar in both twins (Figure 42.3).
