Anatomic relationships in a set of thoracopagus twins

Background: Conjoined twins occur from aberrant embryogenesis, at an estimated incidence of 1 in 200,000 births, with many being stillborn. There are many subtypes of conjoined twins, with their classifications based on anatomical relationships between the two individuals. Similarly, twin survival to birth and potential for surgical separation are based largely on anatomy, especially organ sharing. In the field of pediatric surgery, advances have been made in the understanding of this unique condition and the factors that affect twin survival. This case details the specific anatomy of a set of conjoined female twins. Case Information: Detailed dissection of female conjoined twins reveals unique anatomic relationships and organ sharing between the two. The twins are thoracopagus, or joined at the thorax. Each twin has a separate head and a separate pair of upper and lower extremities. There are distinct, separate abdomens and pelves. The twins share a heart, diaphragm, and liver. Each has separate sets of lungs, and separate foregut, midgut, and hindgut structures. Conclusions: Medical and surgical management of conjoined twins depends largely on the highly variable anatomy and the resulting impacts on physiology. This case report details a set of thoracopagus twins and their unique anatomy. The twins share a heart, which occurs in nearly all thoracopagus twins, and is rarely compatible with life. While the medical history of the twins described here is unknown, a detailed dissection of this well-preserved specimen and exploration of anatomic relationships adds to the current literature and understanding of this unique condition.