Ultrasound prenatal diagnosis of structural abnormalities

Routine screening for congenital abnormalities has become established practice, at least in the developed countries and ultrasound is the major modality used for this. Although 50–60% of all structural abnormalities can be detected as early as 11–14 weeks, the optimum timing for a full structural survey appears to be around 20 weeks. The timing is also governed by termination laws in various countries. One of the problems with screening scans was the variable way in which they were conducted throughout the UK. A minimum standard has been suggested for an anomaly scan in order to bring about uniformity in the screening program. The search for abnormalities can be initiated by a finding of Increased nuchal translucency or abnormal serum biochemistry performed as a part of Down syndrome screening program. Alternatively, a ‘routine’ anomaly scan is offered to all pregnant women. A thorough understanding of the normal ultrasound appearance of fetal structures is essential in order to detect abnormalities. When an abnormality is detected prenatally, the pregnancy usually needs a multidisciplinary team care In order to optimise the outcome.