Predicting aneuploidy in fetuses with cardiac anomalies: significance of visceral situs and noncardiac anomalies.

To determine whether the risk of aneuploidy in fetuses with cardiac anomalies is affected by abnormal visceral situs or coexisting noncardiac anomalies (NCA), were reviewed 125 cases in which a structural cardiac anomaly was detected by prenatal sonography. Forty-three of the 125 fetuses (34%) had an abnormal karyotype (31 autosomal trisomies, 12 other). None of the 13 fetuses with abnormal visceral situs had an abnormal karyotype, whereas an abnormal karyotype was present in 43 of 112 with normal visceral situs (P < 0.01, Fisher's exact test). The karyotype was abnormal in 33 of 52 (63%) with coexisting NCA and in only 10 of 73 (14%) without coexisting NCA (P < 0.001, chi-square). Therefore, among fetuses with structural cardiac anomalies, abnormal visceral situs is strongly predictive (100% in our series) of normal karyotype, whereas the presence of coexisting NCA significantly increases the risk of aneuploidy. These findings can help guide recommendations concerning prenatal karyotyping.