Esophageal Atresia

Etiology

The etiology of esophageal atresia with or without an associated tracheoesophageal fistula is the failure of separation or incomplete development of the foregut.[5] The fistula tract derives from a branch of the embryonic lung bud that fails to undergo branching because of defective epithelial-mesenchymal interactions.[6] 

There have been several genes associated with EA, including Shh,[7] SOX2, CHD7, MYCN, and FANCB.[5] However, etiology is not completely known and is likely multifactorial. Patients can either be diagnosed with isolated EA/TEF or part of a syndrome such as VACTERL or CHARGE.

Epidemiology

EA is a congenital malformation of the upper gastrointestinal tract with an estimated prevalence worldwide varying from 1 in 2500 to 1 in 4500 births.[3] In the United States, the prevalence is estimated to be 2.3 per 10,000 live births.[8] The relative incidence of EA/TEF increases with maternal age.[8]

Pathophysiology

TEF and EA result from the defective lateral separation of foregut into the esophagus and trachea. A fistula tract between the esophagus and the trachea is possibly formed secondary to a defect in epithelial-mesenchymal interactions.[6] TEF and EA are present together in about 90 percent of cases. EA and TEF are classified into 5 categories (types A-E) based on anatomical configuration.[9] 

Type A is isolated esophageal atresia without associated tracheoesophageal fistula and has a prevalence of 8%. Type B is esophageal atresia with a proximal tracheoesophageal fistula. It is the rarest with a prevalence of 1%. Type C esophageal atresia is the most prevalent at 84% and involves a proximal EA with distal tracheoesophageal fistula. Type D is esophageal atresia with both a proximal and distal TEF. It is rare at 3%. Type E esophageal atresia is just an isolated tracheoesophageal fistula without associated esophageal atresia. It is known as an "H" type, with prevalence around 4%.

History and Physical

Approximately one-third of fetuses with EA/TEF will be diagnosed prenatally.[2] The most common sonographic clue to EA is polyhydramnios, which is present in approximately 60% of pregnancies.[2] If diagnosed prenatally, the family can be counseled on expectations after delivery. Furthermore, delivery can occur where specialized teams of maternal-fetal medicine specialists, neonatal intensivists, and pediatric surgeons are available.

However, many cases are not diagnosed before birth. Infants with EA are symptomatic soon after birth, with increased secretions, which leads to choking, respiratory distress, or cyanotic episodes during feeding. In EA types C-E, the fistula between the trachea and distal esophagus results in a gas-filled stomach on a chest x-ray. Infants with EA type A and B will not have stomach distention because there is no fistula from the trachea to the distal esophagus. Infants with TEF may reflux gastric contents through the fistula into the trachea leading to aspiration pneumonia and respiratory distress. Patients with EA type E may have delayed diagnosis if the fistula is small.[4]

Evaluation

EA is typically diagnosed with failure to pass an orogastric tube. The tube will stop short of the stomach and be seen coiled above the level of EA on a chest X-ray. A definitive diagnosis can be made by injecting a small amount of water-soluble contrast material into the orogastric tube under fluoroscopic guidance. Barium should be avoided as it can lead to chemical pneumonitis if aspirated into the lungs. Further diagnosis can be aided using esophagoscopy or bronchoscopy looking for a tracheal fistula.

The neonate with EA and TEF needs evaluation for VACTERL and CHARGE abnormalities, as this can occur in up to 50% of the neonates.[3] Specifically, the complete evaluation requires a cardiac echocardiogram, limb and spine X-rays, renal ultrasound, and thorough physical exam of the anus and genitalia for any abnormalities. A large, single-center U.S. study looked at the most common congenital abnormalities associated with EA/TEF.[10] Among nearly 3,000 patients, the associated VACTERL diagnoses included vertebral anomaly in 25.5%, anorectal malformation in 11.6%, congenital heart disease in 59.1%, renal disease in 21.8% and limb defects in 7.1%.[10] Nearly one third had 3 or more anomalies and met criteria for a VACTERL diagnosis.

Treatment / Management

Once EA is diagnosed, the infant should be intubated to control the airway and help prevent further aspiration. If not already, a catheter should be gently placed to suction oropharyngeal secretions. The infant should be given antibiotics, intravenous fluids, and given nothing by mouth (NPO). Total parenteral nutrition (TPN) should be considered for the infant as NPO status may last several weeks. Once the neonate is stabilized from a hemodynamic and airway standpoint, a pediatric surgeon should be consulted. 

The timing for definitive surgical treatment for EA/TEF depends on the size of the neonate. If the child is greater than 2 kilograms, EA/TEF surgery is typically offered once cardiac anomalies, if present, have been addressed. Very low birth weight neonates (<1500 grams) are typically treated in a staged approach with ligation of the fistula initially, followed by repair of EA once the neonate is larger.[11](B2)

The surgical options for EA/TEF repair include open thoracotomy or video-assisted thoracoscopic surgery.[12] In either operation, the steps involved are similar. The fistula is identified between the esophagus and the trachea and divided. A bronchoscope may be utilized to visualize where on the trachea the fistula originates. After fistula ligation, the esophageal atresia is addressed. Typically, a small nasogastric tube is placed to transverse the two ends, and the ends are sutured together with absorbable suture if the ends reach without too much tension.[12] If there is too much tension on the esophageal ends or they do not reach, the Foker technique can be utilized.[13] This technique uses traction sutures on the esophageal ends and slowly pulls them closer. Once the ends come together without tension, a primary repair can be performed.[13] 

If there is an ultralong gap EA precluding primary anastomosis, then the interposition of another organ such as stomach, colon, or jejunum can be utilized.[14] Patients with EA type E "H-type" may be treated with high cervical incision and avoid a thoracotomy to ligate the fistula.[15] Gastrostomy is usually not indicated unless primary anastomosis fails. (B3)

After surgery, the neonate is returned to the neonatal ICU for close monitoring. A chest tube is left in place on the side the chest was accessed. The neonate is continued NPO with the nasogastric tube to intermittent suction. After 5-7 days, an esophagogram is performed looking for an esophageal leak. If no leak is identified, typically oral feeds are begun. If there is a leak, the chest tube will collect the drainage. The chest tube is left in place until the leak seals and/or the neonate tolerates oral feedings.

Differential Diagnosis

The differential diagnosis for EA/TEF includes laryngotracheoesophageal clefts, esophageal webs or rings, esophageal strictures, tubular esophageal duplications, congenital short esophagus, and tracheal agenesis.[5] These diagnoses can be further investigated with a variety of imaging from x-rays and computed tomography scans to endoscopy and surgery.

Prognosis

The prognosis for neonates with EA/TEF is relatively good and depends mainly on cardiac and chromosomal abnormalities versus the esophageal atresia per se. Generally, overall survival is around 85%-90%.[16] Higher mortality is seen when associated cardiac anomalies are present in addition to EA/TEF. Early deaths are associated with cardiac anomalies, while late deaths are attributed to respiratory complications.[16] The distance between two esophageal pouches, especially if large, may determine prognosis.[17] All neonates who undergo repair of EA/TEF will have some expected gastrointestinal and respiratory issues, which generally improve with age.

Complications

Surgical complications can happen after EA/TEF repair. The most dreaded complication is an esophageal anastomotic leak.[18] Small leaks may be managed with chest tube drainage and prolonged NPO until the leak seals. If there is a large leak or anastomotic dehiscence, then reoperation and resection of the esophagus may be required with gastric, colonic, or jejunal interposition graft.[14] 

Another potential complication is an esophageal anastomotic stricture. These are typically managed with serial endoscopic esophageal dilations.[19] Finally, although rare, re-fistulization of the esophagus and trachea have been reported.[20] These are managed with reoperation. 

Non-surgical complications of having EA/TEF are common. Proton pump inhibitor use is recommended for a minimum of one year after EA/TEF repair due to esophageal dysmotility that leads to increased gastroesophageal reflux (GER) and risk of aspiration.[20] Tracheomalacia is commonly seen after surgical repair. Neonates with EA/TEF typically have increased rates of dysphagia, respiratory tract infections, and esophagitis.[21]

Due to the increased GER throughout childhood into adulthood, these children have increased rates of Barrett's esophagus and have a higher risk of esophageal cancer compared to the general population.[22] Screening protocols for esophageal cancer in these patients is recommended, although this is controversial.[22]