Congenital Anomalies of Esophagus Workup

Antenatal laboratory abnormalities have been reported with this anomaly. In cases of unexplained polyhydramnios, amniocentesis may be performed. An elevated alpha-fetoprotein (AFP) level and a positive acetylcholinesterase test result may be observed. Chromosomal analysis is also performed on the amniotic fluid.

Routine neonatal and preoperative laboratory tests should be obtained.

Antenatal imaging

Ultrasonography

Antenatal detection of esophageal atresia (EA) relies on the finding of a small or absent fetal stomach bubble associated with maternal polyhydramnios on ultrasonography (US). The positive predictive value of this combination is 56%, and the sensitivity of antenatal US in the diagnosis of EA is 42%. The diagnostic accuracy is increased if an anechoic area is also present in the middle fetal neck. Polyhydramnios alone is a poor predictor of EA. Only one in 12 patients with polyhydramnios is found to have EA.

Magnetic resonance imaging

In one study, fetuses with US evidence of EA underwent single-shot rapid-acquisition magnetic resonance imaging (MRI). ^[9] Findings were negative if the entire esophagus could be visualized and positive if the esophagus was absent in the midchest (see the images below). MRI had a sensitivity of 100% and a specificity of 80%.

Plain radiography

The inability to pass a rigid nasogastric tube from the mouth to the stomach is diagnostic of EA. The position of the tip of the tube in the upper pouch is confirmed with a chest radiograph. A small amount of air may be injected into the tube to insufflate the upper pouch.

Air in the stomach and intestine suggests the presence of a distal tracheoesophageal fistula (TEF; see the first image below). A gasless abdomen suggests isolated EA (see the second image below). In cases of EA and distal TEF, the gap length can be estimated by measuring the distance between the tube in the upper pouch and the carina (see the video below). A gap of three or more vertebral bodies or of 5 cm or more is considered long. The gap distance for pure EA is difficult to determine without a gastrostomy in place.

Plain chest radiography also provides information about the presence of associated congenital anomalies. Pneumonitis; atelectasis; cardiac, vertebral, and rib anomalies; and aortic arch location may be discerned from chest radiographs. A right-side aortic arch is indicated roentgenographically by a denser shadow on the right side of the mediastinum, a right-side tracheal indentation, a dilated inlet to the left subclavian artery, and a normal heart configuration.

Contrast studies

Contrast studies are rarely needed but may be necessary to identify or locate a proximal fistula (see the image below). To reduce the complications associated with contrast aspiration, a water-soluble agent should be used. Contrast studies should be performed under fluoroscopic control, and only 0.5-1.0 mL of contrast should be injected and later removed via aspiration.

An isolated, or H-type, fistula presents a different radiographic picture, and establishing the diagnosis is often more difficult. Recurrent pneumonia, particularly of the right upper lobe is suggestive of this condition. Contrast studies specifically looking for the fistula are needed. A tube is placed in the esophagus, and dilute barium is instilled into the esophagus, beginning just above the lower esophageal sphincter. As contrast is injected, the tube is slowly withdrawn in a proximal direction.

This method typically demonstrates only tracheal filling. The fistula is difficult to visualize. A roentgenographic study using videotape or cinefluoroscopy may show an H-fistula not visible on barium swallows, but bronchoscopy or esophagoscopy are often required to confirm the diagnosis. An amotile or hypomotile esophageal segment in a child with recent pneumonia should also alert a fluoroscopist to the possibility of an H-fistula.

Computed tomography and magnetic resonance imaging

Computed tomography (CT) and MRI examinations are rarely needed in the evaluation of EA. Both tests are sensitive and specific for visualization of most great-vessel anomalies, but the high costs and need for transport limit their use. They are more useful when evaluating a mass, such as a foregut duplication or cyst.

Studies to detect duplications

Esophageal duplications are rare. Most are segmental and occur in the posterior mediastinum. Plain chest radiography reveals a round or oval posterior mediastinal mass close to the esophagus, sometimes causing esophageal deviation or compression. The cystic nature of this mass is revealed on CT.

Studies to detect rings

Cartilaginous rings are found in the distal third of the esophagus, whereas nonspecific congenital rings are located in the distal two thirds of the esophagus. Tracheobronchial remnants may coexist with EA (see the image below). Esophageal rings are typically not apparent on radiography unless the distal esophagus is well distended. Barium may fill linear clefts, ducts, or cystic spaces extending perpendicular to the ring. Fluoroscopic examination reveals thickened anular narrowing at the ring site. Note that rings may spontaneously change in caliber and configuration during fluoroscopy.

Studies to detect webs

Esophageal webs are typically located in the proximal esophagus within a few centimeters of the cricopharyngeus. Incomplete webs are placed anteriorly and can be observed only in the lateral projection. Complete webs create a characteristic jet effect distally upon fluoroscopic examination. Just as with esophageal rings, the distal esophagus must be adequately distended in order to visualize the abnormality.

Screening for associated congenital anomalies

The presence of other congenital anomalies affects the choice and timing of the repair. Patients with cardiac, pulmonary, chromosomal, and renal anomalies have higher mortality rates. Echocardiography and renal US should be performed routinely in cases of esophageal anomalies. Echocardiography is used to determine the position of the aortic arch. Chromosomal analyses may also be indicated.

The diagnosis of EA or TEF is suggested by several tests, in addition to the clinical signs previously discussed. After birth, inability to pass a rigid radiopaque 10-French catheter from the mouth to the stomach suggests EA, and diagnosis is confirmed upon identification of the tube, arrested 9-12 cm from the alveolar ridge, in the upper pouch. Presence of air in the stomach and intestines indicates EA with a distal fistula, whereas absence of abdominal gas suggests pure atresia, EA with a proximal fistula, or, rarely, EA with an occluded distal fistula.

A small upper esophageal pouch is suggestive of a proximal fistula, and the presence of a proximal TEF can be confirmed with fluorography, endoscopy, bronchoscopy, or upper esophageal contrast studies. An isolated TEF may be detected by barium esophagography, cinefluoroscopy, bronchoscopy, or esophagoscopy. Because of the risk of aspiration, use of contrast for visualization of congenital esophageal anomalies must be approached with extreme care and performed only by an experienced radiologist.

Esophagoscopy may be used to identify strictures, webs, or fistulas within the upper pouch. A TEF may be better visualized from the tracheal side during bronchoscopy. Retrograde endoscopy through a gastrotomy allows a 3- or 4-French catheter to be placed into the distal esophagus.

Bronchoscopy findings confirm the presence of a fistula and are useful in detecting laryngotracheal clefts. Bronchoscopy provides knowledge of the precise fistula location and can be used to identify proximal TEFs or unusual lesions, such as triple TEF. A small Fogarty catheter can be passed through the fistula and used for occlusion in infants too unstable to undergo fistula ligation. The catheter can also serve as a guide during repair.

Estimating gap length is important in the preoperative period. Gap length may be determined using various techniques (see the image below). High upper pouch, vascular ring, vertebral and rib anomalies, and isolated EA or EA with a proximal fistula are more common if a long gap is present.

In children with pure EA who are undergoing staged repair, gap length is monitored by serial gapograms (see the images below). Contrast is placed through the gastrostomy tube and refluxed into the distal esophagus. The proximal pouch is stretched and visualized with a tube or mercury-weighted dilator (see the images below).

Similarly, a dilator can be placed through a gastrostomy into the distal pouch (see the image below).

During development, the esophageal epithelium undergoes several transitions, from pseudostratified columnar to ciliated columnar. A stratified squamous epithelium appears in the middle third and migrates cranially and caudally until it completely lines the esophagus of the fetus.

Variances in the esophageal epithelium are observed in histologic EA examinations. Tracheobronchial remnants (eg, ciliated pseudostratified columnar epithelium, seromucous glands, cartilage) are often observed. Irregular smooth-muscle fibers are also observed in the distal esophagus of infants with EA and TEF. Fistula tracts may be lined with ciliated respiratory epithelium that extends variable distances from the fistula origin. In addition, the muscular coat of the fistula tract may be absent at the origin. Tracheobronchial remnants as the histologic cause of congenital esophageal stenosis, an associated anomaly of EA, have also been described.

Other congenital anomalies may be noted as well. Histologic investigation of esophageal rings has shown the upper surface to be lined by squamous epithelium, while a columnar epithelium lies below. The ring core consists of a lamina propria with no muscularis mucosa. Inflammation and fibrosis are also absent. Rings may contain tracheobronchial cartilage and respiratory epithelial remnants. The ducts and cystic spaces are typically lined with a respiratory epithelium.

Histologic examinations of esophageal webs have shown plications of normal squamous mucosa with inflammation or patches of heterotopic gastric mucosa. The histologic appearances of foregut cysts differ by type; bronchogenic cysts are lined with respiratory epithelium, gastroenteric cysts are lined by gastrointestinal (GI) epithelium, and neurenteric cysts are lined with GI epithelium, in addition to neural elements.

Congenital stenoses may consist of rings of muscle or tracheobronchial elements.