Evaluation of routine ultrasound examination for the prenatal diagnosis of malformation.

In 1986, a retrospective survey was undertaken in the southern part of the province of Hainaut, Belgium, in order to measure the frequency of ultrasound examinations during pregnancy and to evaluate the effectiveness of the routine practice of echography screening for the detection of congenital malformations in an unselected population. The reference populations comprised 8316 pregnancies covered by the EUROCAT Registry of Hainaut. In 1986, 190 congenital malformations cases were registered. For each of the 190 cases, one control ending in the birth of a non-malformed infant was retrospectively selected. The analysis showed that an average of four ultrasound examinations were performed during pregnancy. When all malformations are considered, the sensitivity of the screening is 14% (27/190). Sensitivity of detection varied from 100% for gross malformations such as anencephaly to 0% for defects of a minor size such as facial clefts. In these 27 cases, obstetrical interventions following prenatal diagnosis were termination of pregnancy in 14 cases and induction of labor in 3 cases. Antenatal care was planned in 8 cases, 5 of which had early surgical repair. In the control group, a malformation was suspected in 3 of the 144 pregnancies (specificity of detection, 98%).