Congenital Anomalies of the Esophagus

The most frequently encountered anomaly in the newborn is esophageal atresia (EA), which occurs with or without tracheoesophageal fistula (TEF). These lesions occur together in 96% of cases except in the case of H-type fistulas ( Fig. 2.1 ). The incidence of EA is 1 in 4500 live births with no gender predilection. Infants born with EA have a 95% chance of survival. TEF and EA occur from an embryonic lung bud that does not branch properly, causing failure of complete separation of the foregut into esophagus and trachea. In 50% of patients there are associated anamolies. These conditions may be present in syndromes such as VACTERL (vertebral abnormalities, anal atresia, cardiac abnormalities, TEF, and/or EA, renal agenesis and dysplasia, and limb defects). Another syndrome is CHARGE (colobama, heart disease, atresia, choanae, retarded growth and development or central nervous system anomalies, genital hypoplasia, ear anomalies, and/or deafness) syndrome, which may involve cardiac or genitourinary abnormalities.

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Congenital Anomalies.

(A1, A2) Proximal pouch with distal fistula, (B) long-gap esophageal atresia (EA), (C) EA with distal and proximal fistulas, (D) isolated H-type tracheoesophageal fistula, (E) congenital atresia caused by stenosing web.

Anatomic classification of EA comprises five categories. The most common category is proximal pouch with distal fistula (A1 and A2), which occurs in 84% of patients. Here the upper esophagus ends at the level of the second thoracic vertebra (T2), leaving a gap of 1 to 2 cm. The lower esophagus enters the trachea at the carina. Over time, the upper esophagus dilates as swallowing ends in a blind pouch. The distal esophagus is of normal caliber but tapers proximally to 3 to 4 mm at its tracheal communication. The second most common EA category is long-gap EA (B), which develops in 8% of patients. In this EA, a fibrous cord connects the proximal and distal parts of the esophagus. Occasionally no cord exists, and the esophagus ends in two pouches. Isolated H-type TEF (D), which can exist anywhere along the posterior wall of the trachea in a normal esophagus, occurs in 4% of patients. EA with distal and proximal fistulas (C) may develop in 6% of patients. Rare variants occur in 2% to 3% of patients; for example, congenital atresia caused by a stenosing web may develop anywhere in the esophagus of a patient with a normal trachea (E).

The pathogenesis of EA remains controversial. In the fetus, the tracheoesophageal septum is a single tube of mesoderm that divides into the esophagus and the lung bud between the fourth and twelfth week of development. The laryngotracheal groove forms the floor of the gut. The esophageal lumen closes as it is filled with epithelium-lining cells. After this, vacuolation occurs, and the lumen is reestablished. An early traumatic event may result in failure of the mesoderm to separate or differentiate during growth of the lung and esophageal components, resulting in reabsorption of a portion of the esophagus. If vacuoles fail to coalesce, a solid core of esophageal cells remains, resulting in atresia. As a result, an abnormal esophagus forms with or without pulmonary communication. Recent evidence indicates that a tracheal fistula may develop as a trifurcation of the trachea that grows and connects to the stomach bud.

Congenital anomalies of the esophagus are frequently associated with organ anomalies. Certain anomalies are incompatible with life unless they are surgically corrected. The most common associated syndrome is the VATER/VACTERL (vertebral, anorectal, cardiac, tracheoesophageal, renal, and limb abnormalities) syndrome, which occurs in 46% of patients; 15% of infants have two or more components of the syndrome.