Conjoined thoracopagus twins.

A case of vaginally delivered stillborn female thoracopagus conjoined twins is presented. Each twin had a cleft lip and cleft palate. They shared a common pericardial sac and a common abdominal cavity. The liver was conjoined, and the small bowel was common to both twins. One twin was asplenic. Although the twins were monozygotic, their viscera were neither identical nor mirror-image to each other, and the visceral anomalies were unique to each twin. The hearts were fused, and communications existed between the circulations at the atrial and ventricular levels. One twin had single atrium, solitary (right) ventricle, malposed great arteries, pulmonary valvular atresia and infundibular stenosis, right aortic arch with aberrant left subclavian artery and with left ductus arteriosus, and atresia of the common pulmonary vein. The other twin had two atrial septal defects of the fossa ovalis and sinus venosus types, partial anomalous pulmonary venous connection, persistent left superior vena cava to coronary sinus, solitary (left) ventricle, malposed great arteries, and left aortic arch with aberrant right subclavian artery and with left ductus arteriosus. There was atrial and ventricular fusion. On hypothetical grounds, and in a comparable anatomic situation, salvage of one twin might be possible by surgical means, while the other twin was sacrificed.