Tracheoesophageal Fistula (TEF) 

TEF is an abnormal connection in one or more places between the esophagus (tube going from the throat to the stomach) and the trachea (tube going from the throat to the windpipe and lungs). These are normally two separate tubes that are not connected. In an infant with a TEF, the lower esophagus connects with the airway. Reflux from the stomach (gastric juices) can pass through the lower part of the esophagus, through the fistula, and into the lungs. This can cause respiratory 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 and possible stomach rupture.

Esophageal Atresia (EA)

TEF often occurs along with another birth defect known as esophageal atresia. With this condition, the esophagus is not properly formed. This results in two segments, one that connects to the throat and the other that connects to the stomach. However, the hollow centers of these two segments do not connect to each other, forming two separate parts. When an infant feeds, the upper part fills up and liquid overflows into the trachea, causing severe respiratory problems. This overflow into the trachea is known as aspiration.

EA takes many forms, and there is a lot of variation in this group of defects. However, the range of the defects includes five main types. The most common type (80 percent) has a fistula between the lower esophagus and the trachea; the upper section is a short part of the esophagus that does not connect with any other structure. The second most common type (10 percent to 12 percent) of defect is EA without a TEF; this is referred to as pure EA.