Esophageal Atresia and Tracheoesophageal Fistula Malformations

Esophageal Atresia With Distal Fistula (Gross Type C)

This is the most common subtype, accounting for about 85% of EA anomalies. In this anomaly, the very dilated proximal esophagus has a thickened wall and descends into the superior mediastinum, usually to a point between the second to third or fourth thoracic vertebrae. The distal esophagus is slender and has a thin wall. It enters the trachea posteriorly either at the level of the carina or 1–2 cm higher. The distance between the esophageal ends varies from very small to quite wide. Very rarely, the distal fistula may be occluded, leading to the misdiagnosis of EA without distal fistula.

Pure Esophageal Atresia Without TEF (Gross Type A)

Pure EA has an incidence of about 7%. The proximal and distal esophagus end blindly in the posterior mediastinum. The proximal end is dilated and has a thickened wall as in the more common EA/TEF. If there is no concomitant proximal fistula, the upper esophagus ends at the level of the azygos vein. The distal esophagus is short and often suspended by a fibrotic band. The distance between the two segments is considerable, usually precluding immediate anastomosis.

H-Type Fistula Without Esophageal Atresia (Gross Type E)

H-type TEF without atresia is usually discussed together with EA because it may be part of the VACTERL association. It occurs with an incidence of about 4%. The fistula starts from the membranous trachea and runs caudad to enter the esophagus. Normally it is short, although the diameter may be variable. The fistula is usually situated at the thoracic aperture or higher in the neck.

Esophageal Atresia With Proximal Fistula (Gross Type B)

The association of a proximal fistula in a patient with pure EA is thought to be about 2% but may be higher than is generally appreciated. In a series of 13 children with EA, but without a distal fistula, a proximal fistula was found in seven. An upper esophageal fistula is usually not found at the end of the pouch. This fistula is similar to the H-type, which starts proximally on the trachea and ends distally in the dilated proximal esophagus. Usually, there is only one proximal fistula, but two or three have been described. The fistula is usually located at the thoracic aperture or higher in the neck. Although limited in length, its diameter may vary from tiny to large. If not diagnosed preoperatively, it may be suspected during operative repair when bubbles are seen on opening the proximal esophagus.

Esophageal Atresia With Proximal and Distal Fistulas (Gross Type D)

The incidence of EA with proximal and distal fistulas is thought to be <1%. EA with one distal fistula and two proximal fistulas has also been described. Also reported is a near-complete membranous obstruction of the esophagus in conjunction with a single TEF at the level of the membrane, communicating with both parts of the esophagus.

Antenatal Diagnosis

The prenatal diagnosis of EA/TEF relies, in principle, on two nonspecific signs: polyhydramnios and an absent or small stomach bubble. Polyhydramnios is associated with a wide range of fetal abnormalities and is nonspecific. Similarly, the ultrasonographic (US) absence of a stomach bubble may point to a variety of fetal anomalies. The combination of a small stomach together with a dilated cervical esophagus (the pouch sign) has been confirmed to be diagnostic for pure EA in a number of patients. Nevertheless, it is encountered in only a few patients. Current US technology does not allow for the certain diagnosis of EA/TEF. Therefore, definitive counseling of the parents should be guarded. Three-dimensional power Doppler imaging has been used both antenatally and postnatally. For example, aortic arch anomalies have been diagnosed using this modality.

Magnetic resonance imaging (MRI) has been used to identify other fetal thoracic lesions, and may be beneficial in patients deemed to be at risk on prenatal US. Sensitivity in various studies is between 60% and 100%, and the diagnosis is made by the lack of visualization of the thoracic esophagus.

Postnatal Diagnosis

If the pregnancy was complicated by polyhydramnios, passage of a tube or catheter into the stomach should be performed to assess esophageal patency. The same holds true when the child presents with anomalies that fit the VACTERL association (e.g., radial aplasia).

As EA prevents the passage of saliva down the esophagus, saliva accumulates in the proximal esophagus and mouth, and feeding should be withheld until esophageal continuity is confirmed. This is best done with a stiff 10 French catheter inserted either through the nose or mouth. A chest film is then obtained with downward pressure on the tube. With EA, the tip of the tube is found to be slightly curled in the blind upper pouch around T2–T4 ( Fig. 27.2 ). This technique not only identifies the atresia but gives some clue about the length of the upper pouch. Often, the dilated upper esophageal pouch is visualized by air within it. Air in the stomach signifies the presence of a distal TEF. If the tip of the catheter passes beyond the level of the carina, then the diagnosis of EA should be questioned. Esophageal stenosis, tracheal rings, and iatrogenic perforation of the esophagus can be confused with EA. If there is any question about the diagnosis, a small amount of contrast can be dripped into the upper pouch, but this needs to be done with fluoroscopy and under direction of the surgeon to ensure that the contrast is not aspirated.

Radiographs may reveal associated anomalies such as vertebral and rib anomalies, or other problems such as duodenal atresia ( Fig. 27.3 ). The absence of air in the stomach points to EA without distal fistula (see Fig. 27.3A ). Mediastinal US has been described as a helpful adjunct in the diagnosis of pure EA.

The length of the esophageal gap is usually not known preoperatively. Absence of air in the stomach has been linked with a long gap, but has also been described in association with a distal fistula occluded with mucus. Even in long-gap EA (atresia without distal fistula) as recently defined by the International Network of Esophageal Atresia (INoEA), the gap length can vary. In newborns with isolated EA, the first procedure is generally a gastrostomy, which allows for enteral feeding and also allows for assessment of the length and location of the lower pouch. It can be identified radiologically, either with metal bougies, a small gastroscope, or with a contrast injected through the gastrostomy. This can be done at the time of the initial gastrostomy or more routinely 7–10 days later. If bougies or a telescope are introduced into the distal esophagus, the amount of pressure on these instruments will affect the measurement of the gap between the two esophageal segments and may under- or overestimate the gap length. In one report by an experienced surgeon, operative management was linked to the measured gap length: fewer than two vertebrae, then primary anastomosis; two to six vertebrae, then delayed primary anastomosis; more than six vertebrae, then esophageal replacement. In the era of thoracoscopy, an initial thoracic exploration can be considered if the upper pouch appears fairly long. If the lower pouch is identified and seen to be of adequate length, a primary repair can be attempted. If not, then a gastrostomy can be placed and delayed repair planned. More recently, van der Zee et al. have advocated for early thoracoscopic exploration without gastrostomy and the use of an internal traction technique to achieve an anastomosis in the first week or two of life. Although this approach appears promising, more study is needed to validate this aggressive early approach.

In EA/TEF, a longer gap between the two esophageal ends should be expected when the distal fistula is found at the carina. Combined with a short upper pouch, this can mean a long gap exists between the two esophageal segments and may not be amenable to an initial primary repair. Unfortunately, this may not fully be appreciated until the time of exploration. However, because it is usually necessary to ligate the fistula in the early postnatal period, the gap length can be assessed at that time. A thoracoscopic approach in this scenario allows for minimal morbidity if the decision is to ligate the fistula only without esophageal reconstruction. Bronchoscopy can also be performed prior to exploration, not only to assess the site of the distal fistula, but to also look for an upper pouch fistula. As previously mentioned, a proximal fistula has been found with a much higher incidence in cases of pure EA than previously reported, in one series up to 50%.

Echocardiography should be performed prior to operation, as it may reveal cardiac and/or aortic arch anomalies. A right descending aorta, which occurs in about 3% of the cases, may make a left-sided thoracic approach preferable. Renal US and spine radiographs should be obtained as well. Because EA may be part of a syndrome, consultation by a geneticist is recommended at some point.

There is little doubt that better preoperative imaging of the neck and chest allows for better preoperative planning. At present, the two best imaging modalities are computed tomography (CT) and MRI. Although MRI would certainly be preferable due to its absence of radiation exposure, it requires general anesthesia. However, MRI is better for diagnosing cardiac and aortic arch anomalies. CT has also been performed in children with EA/TEF, but in truth both these advanced studies add little to the routine management of this congenital anomaly.