Hirschsprung Disease

Oesophageal atresia is congenital discontinuity of the oesophageal lumen, with the proximal oesophagus ending blindly. Most cases are associated with a tracheoesophageal fistula.

Failure of separation and elongation of the primitive foregut results in variable oesophageal and tracheal anatomy.

The major immediate dangers are:

• Aspiration of pooled proximal oesophageal secretions
• Gastric distension through a distal tracheoesophageal fistula
• Respiratory compromise
• Associated congenital anomalies

Gross anatomical classification

Type A

Pure oesophageal atresia without fistula.

Both oesophageal ends are blind.

Approximately 7% to 8%.

Frequently produces a long gap.

Type B

Oesophageal atresia with proximal tracheoesophageal fistula.

Rare.

Type C

Oesophageal atresia with distal tracheoesophageal fistula.

By far the commonest pattern, approximately 80% to 85%.

The proximal oesophagus ends blindly and the distal oesophagus communicates with the trachea.

Type D

Oesophageal atresia with both proximal and distal fistulas.

Rare.

Type E

Tracheoesophageal fistula without oesophageal atresia, commonly called an H type fistula.

Oesophageal continuity is preserved.

Associated anomalies

A systematic search for associated malformations is essential.

The VACTERL association includes:

• Vertebral anomalies
• Anorectal malformation
• Cardiac defects
• Tracheoesophageal fistula
• Renal anomalies
• Limb abnormalities

Cardiac disease is particularly important because it affects anaesthesia, operative approach and postoperative physiology.

Long term disease does not end after neonatal repair. Survivors are prone to:

• Gastroesophageal reflux
• Oesophageal dysmotility
• Anastomotic stricture
• Recurrent fistula
• Tracheomalacia
• Feeding difficulty
• Aspiration
• Chronic respiratory symptoms

Prenatal features can include:

• Polyhydramnios
• Small or absent fetal stomach, particularly in pure atresia

After birth, typical findings are:

• Excessive salivation
• Frothing from the mouth
• Coughing or choking during attempted feeding
• Cyanotic episodes
• Respiratory distress

Attempted passage of an orogastric tube meets resistance, usually at approximately 10 to 12 cm from the gums.

In type C disease, air entering through the distal fistula produces abdominal distension.

In pure atresia without a distal fistula, the abdomen is typically relatively gasless.

Marked abdominal distension in a ventilated infant can impair diaphragmatic excursion and worsen respiratory failure because positive pressure ventilation forces gas through the distal fistula into the stomach.

Pass a soft radiopaque orogastric tube when oesophageal atresia is suspected.

Chest and abdominal radiograph: confirms the tube coiled within the upper oesophageal pouch and determines whether gastrointestinal gas is present.

Gas within the stomach and bowel strongly suggests a distal fistula.

Avoid routine contrast instillation into the proximal pouch because aspiration can cause severe pneumonitis.

Perform echocardiography before definitive repair where possible to identify:

• Congenital cardiac disease
• Side of the aortic arch

Evaluate for vertebral, renal, limb and anorectal anomalies.

Bronchoscopy before or during repair can define:

• Site of distal fistula
• Additional proximal fistula
• Tracheomalacia
• Other airway abnormalities

Immediate neonatal stabilisation

Keep the infant nil orally.

Place a large bore double lumen Replogle tube into the proximal oesophageal pouch and use continuous low pressure suction.

Keep the head elevated approximately 30° to 45°.

Suction the upper pouch frequently enough to prevent pooling of saliva.

Avoid routine bag mask positive pressure ventilation because gas can pass through a distal fistula into the stomach and produce severe gastric distension.

If respiratory support is required, use endotracheal intubation with careful positioning of the tube.

When the distal fistula enters the trachea relatively high, positioning the endotracheal tube tip distal to the fistula but proximal to the carina may reduce gastric ventilation, although anatomy may make this impossible.

Correct:

• Hypothermia
• Hypoglycaemia
• Dehydration
• Respiratory failure
• Associated sepsis

Routine broad antibiotics are not required simply because oesophageal atresia exists, but perioperative prophylaxis is appropriate.

Definitive repair

For the common type C lesion, surgery consists of:

• Identify the distal tracheoesophageal fistula
• Divide and securely close the fistula at the tracheal end
• Mobilise the upper and lower oesophageal segments carefully
• Construct a primary oesophagoesophageal anastomosis when the ends can meet without unacceptable tension

Repair can be performed through:

• Right posterolateral thoracotomy
• Muscle sparing thoracotomy
• Thoracoscopic approach in suitable infants and experienced centres

A right sided approach is conventional because the aortic arch usually lies to the left.

If a right sided aortic arch exists, operative strategy should be planned carefully because the usual anatomical exposure changes.

Anastomotic principles

Preserve oesophageal blood supply during mobilisation.

Avoid excessive circumferential stripping.

Create a mucosa to mucosa anastomosis with fine absorbable sutures.

A small amount of anastomotic tension is often tolerated, but major tension substantially increases:

• Leak
• Stricture
• Anastomotic disruption

Long gap oesophageal atresia

Long gap disease is most commonly seen with pure atresia.

The first objective is preservation of the native oesophagus whenever reasonably achievable.

Options include:

Delayed primary anastomosis

Provide gastrostomy feeding and allow spontaneous oesophageal growth before later anastomosis.

Traction based lengthening

Controlled traction can stimulate oesophageal elongation in specialist centres.

Oesophageal replacement

Use only when native oesophageal continuity cannot reasonably be achieved.

Options include:

• Gastric transposition
• Gastric tube
• Jejunal interposition
• Colonic interposition

Each has substantial long term morbidity, so replacement should not be chosen casually when native oesophageal preservation remains possible.

Gastrostomy

Gastrostomy is not necessary for every routine type C repair.

It is more useful with:

• Long gap atresia
• Need for prolonged enteral access
• Major associated anomalies delaying repair
• Selected high risk infants

Anastomotic leak

A small contained postoperative leak can often be treated with:

• Nil oral intake
• Continued drainage
• Nutritional support
• Antibiotics when contamination or infection is present

Major uncontrolled disruption, mediastinal sepsis or clinical deterioration requires operative reassessment.

Anastomotic stricture

Suspect when the infant develops:

• Dysphagia
• Feed refusal
• Food impaction
• Recurrent aspiration

Treat symptomatic anastomotic strictures with endoscopic balloon or bougie dilation.

Repeated refractory strictures should trigger evaluation for severe reflux, recurrent fistula or another structural problem.

Gastroesophageal reflux

Reflux is common because of:

• Abnormal oesophageal motility
• Altered oesophageal anatomy
• Anastomotic tension

Use acid suppression for clinically important oesophagitis or reflux related complications.

Fundoplication is reserved for severe refractory disease, particularly with aspiration, failure to thrive or reflux associated recurrent strictures.

Recurrent tracheoesophageal fistula

Suspect with:

• Coughing during feeds
• Recurrent pneumonia
• Cyanotic feeding episodes
• Persistent abdominal distension during ventilation

Diagnosis may require bronchoscopy combined with carefully performed contrast evaluation.

Definitive treatment usually requires fistula division with interposition of vascularised tissue between tracheal and oesophageal repairs.