Tracheoesophageal fistula (TEF) is a medical condition where there is an abnormal connection, or fistula, between the trachea (windpipe) and the esophagus (food pipe). In newborns, TEF occurs as a congenital birth defect caused by the failure of the trachea and esophagus to separate during fetal development. Symptoms of TEF include difficulty feeding, choking, coughing, and respiratory distress. In some cases, an infant may also develop aspiration pneumonia due to food or liquid entering the lungs through the fistula. Once diagnosed, prompt surgery is required to allow the food intake.