A case of holoacardius is presented from a monozygotic twin pregnancy of 20 weeks, in which the other twin was normal. The classification is reviewed. While the physiology and anatomy of these malformations are known, the etiology remains obscure. Theories of etiology may be divided in two groups: that the primary deficiency is a failure of the parts to develop; and the belief that the acardius is due to an abnormal vascular communication with secondary atrophy of the formed parts. The abnormal twin in the case studied was diagnosed by ultrasound prenatally and investigated radiologically post-mortem.
- monozygotic twin pregnancy