Congenital diaphragmatic hernia in monozygotic twins.

This is the third reported instance of identical twins, each with left-sided posterolateral congenital diaphragmatic hernia (CDH) (Bochdalek type), who have been operated upon successfully. The associated anomalies were mirror image undescended testicles. Comparative review of familial and sporadic cases of CDH revealed that males were more commonly affected in the former, while females were more commonly affected in the latter. There was no known etiology in either type. Both familial and sporadic cases shared a high incidence of associated anomalies (40% to 50%). Three anomalies were equally found in both types, mainly pulmonary hypoplasia, intestinal malrotation, and patent ductus arteriosus. Central nervous system anomalies were highly prevalent in the sporadic cases (55% to 75%), while cardiovascular and genitourinary anomalies (30% each) were the more common anomalies encountered in the familial cases.