Fetal abnormalities detected by sonography in low-risk pregnancies: discrepancies between pre- and post-termination findings.

In this geographically based study the findings on 158 abnormal fetuses, primarily diagnosed by routine antenatal ultrasound, are correlated with the results of the examinations subsequently carried out by a fetopathologist and a clinical geneticist. Ninety fetuses (57%) had a single malformation, 66 were polymalformed (42%) and 2 had no malformations. In 90% of all these cases, the prenatally and postnatally detected anomalies were identical; in 3% the defect established at necropsy was different from that diagnosed prenatally, and in 7% the predicted anomaly was absent. These values did not depend on whether single or multiple malformations were involved. In 57% of the polymalformed cases, however, the ultrasound examination missed at least one other diagnosable anomaly. On the basis of pathological and clinical genetic expertise, a risk of recurrence of the anomaly was revised in 13% of the single malformed cases and in 53% of the multiple ones, i.e., in 30% of all the cases of malformation on average. This study confirms the need for the fetus to be examined by a pathologist and a clinical geneticist after termination of a not 'at risk' pregnancy in order to check the accuracy of the sonographic procedure, to confirm the reasons for terminating the pregnancy to the parents, and to be able to monitor the next pregnancy based on an accurate assessment of the risk of recurrence.