A congenital anomaly in which there has been failure of fetal separation of the TRACHEA and OESOPHAGUS so that a communication remains between them after birth. In the most severe cases, it is combined with oesophageal atresia, in which there is a blind end to the oesophagus rather than it communicating with the stomach. A baby who has a fistula without atresia may present with pneumonia due to aspiration of feed into the lungs or, where the connection is small, with recurring cough and chest infections. Treatment is by surgical repair.