Detection of fetal major structural anomalies at the 11-14 ultrasound scan in an unselected population.

OBJECTIVE: The aim of the study was to determine the efficacy of the 11-14 week scan in detecting fetuses with structural anomalies. STUDY DESIGN AND METHODS: Prospective interventional study in an unselected population of pregnant women in a 5-year period (2003-2008) in a single ultrasound unit. 8889 fetuses with median CRL 65mm (45-84mm) were examined. Continuing pregnancies were rescanned at 20-22 weeks. Actual structural anomalies among newborns from the studied group were obtained from our computerized database. RESULTS: The median maternal age was 30 years (14-50 years). The incidence of anomalies was 16.08 per 1000 (143/8889). Of these, 99 of the 143 were detected with prenatal sonography. 46.9% (67/143) of all anomalies were detected at the 11-14 week scan. Later in pregnancy, another 22.3% (32/143) of structural anomalies were detected. CONCLUSIONS: 67.7% of all antenatally detected malformations by ultrasound were recognized in the 11 14 week scan. Obviously, the second trimester scan cannot be abandoned, as it provides effective detection of other anomalies.