Accessory septum transversum. The first case report.

Duplication of the septum transversum occurred in a newborn with respiratory distress thought clinically to be due to diaphragmatic paralysis. Surgical plication of the "floppy" diaphragm was attempted via a transabdominal approach. The anomalous septum transversum was perceived to be the diaphragm and was plicated. The central tendon of the diaphragm was redundant and surgical plication may have improved respiratory function. In this first case report, embryology of the diaphragm is reviewed and correlated with autopsy findings. A surgical approach to possible correction is proposed.