Tracheoesophageal Fistula (TEF) 

TEF is an abnormal opening in one or more places between the esophagus (tube going from the mouth to the stomach) and the trachea (windpipe that goes from the throat to the lungs). These are normally two separate tubes. Saliva or gastric juices can pass from the esophagus, through the opening, and into the lungs. This can cause breathing and lung problems.

In premature infants who have underdeveloped lungs and a TEF, air may go from the trachea into the esophagus and stomach, causing severe belly swelling, possible stomach rupture, and respiratory distress.

Esophageal Atresia (EA)

TEF is often seen with another birth defect known as esophageal atresia. In this condition, the esophagus does not fully form and there is not a connection from the mouth to the stomach.