OC29.08: Prenatal Diagnosis of an Isolated Fetal Malformation: the Accuracy of Ultrasound in Excluding Additional Anomalies

Objective: One major problem in counselling couples with a prenatal diagnosis of a correctable fetal anomaly is the ability to exclude associated malformations that may modify the prognosis. Our aim was to assess the precision of fetal sonography in identifying isolated malformations. Methods: We retrospectively reviewed the prenatal and postnatal records of our center for cases with a prenatal diagnosis of an isolated fetal anomaly in the period 2002–2004. Results: The antenatal diagnosis of an isolated malformation was made in 151 cases. In one of this cases the anomaly disappeared in utero. Of the remaining cases, the prenatal diagnosis was confirmed after birth in 135 (90%). In 5 fetuses (all with a suspected coarctation of the aorta) the prenatal diagnosis was not confirmed. In 10 fetuses (6.7%) additional malformations were detected at postnatal or post-mortem. In 7 of these cases the anomalies were mild or would not have changed the prognosis. In 3 cases (2%) severe anomalies were present (1 hypoplasia of the corpus callosum with ventriculomegaly, one tracheal agenesis, one multiple anomalies). Two of these infants died. Conclusions: the prenatal diagnosis of an isolated fetal anomaly is highly reliable. However, the probability that additional malformations will go undetected albeit small remains tangible. In our experience, it was 2%.