Thoracopagus conjoined twins.

The incidence of conjoined twins is estimated at 1 in 50 000 births.1 Thoracopagus is the most common form of conjoined twins,2 with fusion from the anterior thorax to the umbilicus. A common pericardial sac is present in 90% of thoracopagus twins, and conjoined hearts are seen in 75%.3 The present case was diagnosed prenatally, and the twins subsequently experienced intrauterine demise at 22 weeks gestation. Postmortem angiography demonstrated conjoined hearts with a left ventricle common to both twins (Figure). At autopsy, the cardiac anatomy for both hearts was found to be an unbalanced complete atrioventricular canal defect with a common left ventricle.