Prenatal detection of cardiovascular malformations by echocardiography: an indication for cytogenetic evaluation.

Prenatal diagnosis of congenital cardiovascular malformations by echocardiography may signal associated chromosome abnormalities. The exact proportion of these associations is not known but is expected to be higher than that with live-birth. To estimate the risk that a fetus with an echocardiographically detected heart defect has an autosomal trisomy or Turner syndrome, we adjusted the known frequency of aneuploidy in live-born infants with congenital cardiovascular malformations by the reported rate of spontaneous abortion, with data from a population-based case-control study of congenital cardiovascular malformations in which 268 cases (12.7%) had both congenital cardiovascular malformations and a chromosome abnormality. Included in the present analysis were 188 aneuploid infants with congenital cardiovascular malformations that would have been detectable by fetal echo. When data are adjusted for the high spontaneous abortion rate of aneuploid fetuses, we estimate that there would have been more than a threefold increase in aneuploidy over the 13% seen at live-birth. Thus cytogenetic analysis is appropriate in a fetus with echo-diagnosed congenital cardiovascular malformations.