Antenatal detection of congenital malformations by routine ultrasonography.

Routine ultrasound examination was performed in 9012 fetuses of a general pregnant population to detect fetal malformations. The examination was done on 3098 fetuses at 18 weeks, and on 5914 fetuses it was repeated at 34 weeks. Ninety-three infants (1.03%) showed 123 major malformations, of which 65 (52.8%) in 54 children were visualized in utero. The sensitivity of detection of malformed fetuses was 58.1% (54 of 93), specificity 99.9%, positive predictive value 91.5%, and negative predictive value 99.6%. Five fetal hydronephroses were the only false-positive cases (0.06%), with apparent spontaneous resolution after birth. Fetal growth retardation, polyhydramnios, or oligohydramnios was observed in 43% of the malformed cases, suggesting the importance of these conditions in ultrasound screening. Abnormality of pregnancy was suspected clinically in only 25.8% of the cases at the time of diagnosis of fetal malformation, emphasizing the necessity for ultrasound examination of all pregnancies.