Fetal anatomical survey during second trimester screening examination

Screening for fetal malformations is one of the main aims of ultrasonography during pregnancy. In most cases fetal anomalies occur as an unexpected event in not at risk patients: For this reason the only way to rule out congenital malformations is to screen every pregnant patient with a systematic evaluation of the fetal anatomy. The ultrasonic screening of fetal malformations has to be based on a single examination that has to be planned at a gestational age which is advanced enough to visualize most fetal anomalies and early enough to plan further diagnostic tests and allow the termination of pregnancy in the case of severe malformation. The gestational age that constitutes the best compromise between the need of an early diagnosis and the natural history of most congenital malformations is the period ranging from 19 to 21 weeks of gestation. This ultrasonic examination is known as 'fetal anomaly scan' or 'fetal morphology scan'. Some scientific societies suggest guidelines for the optimal performance of such examination. In this paper the minimal standards for an accurate 'fetal morphology scan' will be described. © Jaypee Brothers Medical Publishers (P) Ltd