Acardiac anomaly: review of the subject with case report and emphasis on practical sonography.

The acardiac anomaly is a rare condition found only in monozygotic multiple pregnancies, usually twins. We present a review of the pathophysiology of acardia and a case report. Twin embryonic membrane formation is discussed, since a conceptual understanding of the subject is necessary for the early recognition of this and other severe anomalies. Emphasis is placed on close sonographic monitoring to insure the best chance of survival of the normal twin, who may die of heart failure if delivery is not properly timed.