In this malformation there is an abnormal communication between the trachea and esophagus. It occurs in about 1 in 3500 live births and most of the affected children are males. Basic defect in this malformation is defective development of the tracheoesophageal septum. In most of the cases the tracheoesophageal fistula is accompanied by esophageal atresia. Four varieties of tracheoesophageal fistula are recognized which are described below. It is to be mentioned here that most (85% to 90%) case of tracheoesophageal fistula belong to the first variety. Remaining three varieties are rarely encountered.
i) In this most common variety, the superior part of the esophagus ends blindly (esophageal atresia), whereas the inferior part of the esophagus opens into the trachea near its bifurcation into principal bronchi.
ii) Sometimes there is no esophageal atresia and the anterior wall of the esophagus has an anomalous communication with the posterior wall of the trachea near its bifurcation.
iii) In some cases the superior part of the esophagus opens into the
posterior trachea! wall, whereas the inferior segment of the esophagus is atretic (ie, begins blindly).
iv) In very few cases the esophagus is divided into an upper and a lower segment, both of which open (by separate orifices) into the posterior wall of trachea.