Esophageal atresia
Synonyms and keywords:  Esophageal Atresias; Atresia, Esophageal; Atresias, Esophageal

# Overview
Esophageal atresia is the commonest congenital esophageal anomaly. In esophageal atresia there is a discontinuity between upper and lower esophagus. It is associated with multiple genetic and chromosomal abnormalities. Thus, it can present in multiple ways. Prenatal diagnosis is possible by using ultrasound or MRI, while x-ray is most commonly used for postnatal diagnosis of esophageal atresia. Definitive treatment involves surgical repair of the anomaly. In the absence of treatment prognosis is very poor.

# Historical Perspective
- Esophageal atresia was first discovered by William Durston, in 1670 in one of the conjoined twins. .
- Thomas Gibson described proximal esophageal atresia with distal tracheo-esophageal fistula in 1697. While Thomas Hill presented a case of esophageal atresia with rectal agenesis in 1840.

# Classification
- Esophageal atresia may be classified according to presence or location of tracheo-esophageal fistula into  subtypes:
- Esophageal atresia without tracheo-esophageal fistula also known as Gross type A.
- Esophageal atresia with proximal tracheo-esophageal fistula also known as Gross type B.
- Esophageal atresia with distal tracheo-esophageal fistula also known as Gross type C.
- Esophageal atresia with distal and proximal tracheo-esophageal fistula also known as Gross type D.
- Tracheo-esophageal fistula without esophageal atresia also known as Gross type E.

# Pathophysiology
- The pathogenesis of esophageal atresia is characterized by abnormalities during embryonic foregut development.
- The Nkx2.1 and SOX2 genes have been associated with the development of esophageal atresia. Nks2.1 and SOX2 are transcription factors involved in the formation of normal esophagus and trachea from embryonic foregut. The activity of these transcription factors is precisely regulated by NOGGIN (BMP-4 anatgonist) and WNT protein. Any abnormality in these genes or signaling pathways can hinder the normal development of trachea and esophagus.   Sonic hedgehog is another signaling pathway involved in embryonic foregut differentiation. The main function of sonic hedgehog is to regulate FOX genes. Abnormal expression of FOXF1 gene has been associated with esophageal atresia.  In animal models, retinoic acid signaling abnormalities have also been associated with abnormal foregut differentiation, although this association has not been confirmed in humans.  Role of adriamycin in the development of esophageal atresia has been studied in animal models. Adriamycin can lead to esophageal atresia in rats but the mechanism remains unclear. Defective apoptosis in foregut and abnormalities in notochord have been proposed as potential mechanisms for the development of esophageal atresia by adriamycin use.

# Causes
Common causes of esophageal atresia include CHARGE syndrome, VACTERL, Fanconi anemia, AEG syndrome, Pallister hall syndrome, Feingold syndrome, Trisomy 21, Trisomy 18, Trisomy 13, Trisomy X.  

# Differentiating esophageal atresia from other Diseases
- Esophageal atresia must be differentiated from other diseases that may cause dysphagia, aspiration, such as:
- Esophageal webs
- Esophageal stricture
- Esophageal diverticulum
- Laryngotracheoesophageal cleft
- Tubular esophageal duplications
- Congenital short esophagus

# Epidemiology and Demographics
- The prevalence of esophageal atresia is approximately  per 100,000 births worldwide. 

## Age
- Esophageal atresia is a congenital defect. It may be diagnosed prenatally or postnatally.

## Gender
- Esophageal atresia affects males and females equally.

## Race
- There is no racial predilection for esophageal atresia.

# Risk Factors
- Common risk factors in the development of esophageal atresia are genetic mutations, chromosomal anormalities, maternal alcohol consumption, maternal smoking, maternal use of methimazole, maternal exposure to exogenous sex hormones, vitamin A deficiency. 

# Natural History, Complications and Prognosis
- If left untreated, a large proportion of patients with esophageal atresia may progress to develop respiratory distress, or  dehydration, and  eventually die soon after birth. 
- Common complications of esophageal atresia include GERD, esophageal stricture, tracheomalacia, recurrent pulmonary infections, airway hyperreactivity, impaired lung function, anastomotic leak from the surgical repair site. 
- Prognosis of untreated esophageal atresia is generally poor. A study assessed the survival of patients of esophageal atresia or tracheoesophageal fistula treated at a center over a period of 37 years. Survival rate in this study was 83%. This study also showed that survival rate of treated patients improved over time.

# Diagnosis

## Diagnostic Criteria
- There is no established criteria for diagnosis of esophageal atresia.

## History and Symptoms
- Symptoms of esophageal atresia may include the following: 
- Drooling
- Dysphagia
- Feeding difficulties
- GERD
- Choking
- Aspiration
- Food aversion as a consequence of above-mentioned symptoms
- blowing bubbles at birth indicating saliva mixed with air because of the concomitant presence of tracheoesophageal fistula in most cases of esophageal atresia.

## Physical Examination
- As esophageal atresia can be a feature of many syndromes so physical examination may be remarkable for:
- respiratory distress
- Cardiac anomalies
- Choanal atresia
- Growth retardation
- genital anomalies
- ear anomalies
- hearing loss
- Syndactyly
- anal atresia
- limb anomalies
- vertebral anomalies

## Laboratory Findings
- There are no specific laboratory findings associated with esophageal atresia.

## Electrocardiogram
There are no ECG findings associated with esophageal atresia.

## X-ray
An x-ray may be helpful in the diagnosis of esophageal atresia. Usually, it is impossible to pass oral catheter beyond 10 to 15cm in esophageal atresia. Anterioposterior chest x-ray can confirm it by showing twisted catheter in the upper esophagus. Plain x-ray may also show absence of gastric bubble. If the diagnosis is unconfirmed, contrast administration under fluoroscopic guidance can confirm the presence of esophageal atresia.

## Echocardiography or Ultrasound
Ultrasound  may be helpful in the antenatal diagnosis of esophageal atresia. Findings on an ultrasound suggestive of esophageal atresia include polyhydramnios from 24th week of gestation onwards, small or absent stomach bubble (indicating absence of fluid in stomach) from 14th week of gestation onwards. These findings are not specific for esophageal atresia and may be present in other congenital abnormalities. Dilated esophagus with blind end is sometimes seen on ultrasound as an echoic area in the midline of fetal neck(pouch sign) from 3rd trimester onwards. 
Polyhydramnios and stomach bubble sign may be absent if distal tracheo-esophageal fistula is present with esophageal atresia as some amniotic fluid may pass through the fistula. If esophageal atresia is accompanied by proximal tracheo-esophageal fistula then pouch sign may be difficult to observe owing to leakage of fluid through the fistula. Echocardiography and renal ultrasound are recommended for all the patients with esophageal atresia, as it can be a manifestation of syndromes like CHARGE syndrome, VACTERL association. 

## CT scan
Ct scan is not routinely used for diagnosis of esophageal atresia. When used, 3D Ct scan can provide detailed information regarding anatomic aspects of esophageal atresia. 

## MRI
Fetal MRI may be helpful in the diagnosis of , as it can confirm the findings detected on ultrasound. In addition to polyhydramnios, pouch sign, bubble sign, MRI can also detect distended fetal hypopharynx sign which occurs as a consequence of hypopharynx distension because of obstruction. 

## Other Imaging Findings
There are no other imaging findings associated with esophageal atresia.

## Other Diagnostic Studies
There are no other diagnostic studies associated with the esophageal atresia.

# Treatment

## Medical Therapy
- There is no medical therapy for esophageal atresia; the mainstay of therapy is surgery.

## Surgery
- Surgery is the mainstay of therapy for esophageal atresia. Preoperative management includes placement of replogle tube on continuous suction with patient in reverse Trendelenburg position to avoid aspiration. Oral feed should be stopped and patient should be put on parenteral nutrition. Surgical treatment of esophageal atresia involves anastomosis of both esophageal ends with repair of tracheoesophageal fistula if present. Commonly implied surgical approaches include extrapleural approach, pleural approach, thoracospcopic approach. Surgical repair may be difficult if the gap between the 2 esophageal segments is too large. In such cases, surgery is delayed by 2 to 9 months to permit esophageal growth until it is suitable to perform surgery. Other factors that can delay surgical repair of esophageal atresia include low birth weight, preterm birth, pneumonia, significant congenital anomalies other than esophageal atresia.  

## Prevention
- There are no primary preventive measures available for esophageal atresia.