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12.09.06 Tracheo-oesophageal fistula

Definition
  • Malformation that arises from defective separation of the oesophagus and trachea
  • Most commonly results in a blind-ending upper oesophageal pouch with a fistulous connection between the distal oesophageal segment and the trachea
  • Gross classification
    • Type A
      • Pure atresia (4% to 7%)
    • Type B
      • Proximal fistula with distal atresia (1%)
    • Type C
      • Proximal atresia with distal fistula (85% to 90%)
    • Type D
      • Proximal and distal fistula (3%) 
    • Type E
      • H-type fistula (2% to 3%); tracheoesophageal fistula without esophageal atresia

Risk factors
  • Trisomy 18 and 21
  • Family history
Differential diagnosis
  • Laryngeal cleft
    • These patients can present with symptoms similar to an H-type fistula with cyanotic spells, feeding difficulties, and recurrent chest infections
    • Best differentiated from a tracheo-oesophageal fistula by rigid bronchoscopy and oesophagoscopy
Epidemiology
  • One in every 3,000 births are affected, with a slight female preponderance
  • The majority of infants have Gross type C
    • 85% to 90% of all cases
    • Diagnosis typically occurs at or shortly following birth due to the blind proximal pouch
  • The second most common type is a pure atresia (Gross A), which comprises 4% to 7% of all tracheo-oesophageal fistulas
  • Gross type D occurs 3% of the time
  • A much rarer form, the H-type fistula (Gross E), occurs in approximately 2% to 3% of cases
    • This type of fistula may be undiagnosed until later in life
  • Type B occurs only 1% of the time
Aetiology
  • The trachea and oesophagus arise from the common foregut
    • Initially starts as a common tube, then separates into 2 distinct tracheal tubes
  • The trachea has primitive lung buds at the caudal end of the primitive trachea
  • The separation starts during the 4th week of gestation
    • A failure of normal division can result in various defects including atresias and fistula formation
  • This failure in organogenesis may be secondary to a failure of gene expression
    • Suspected genes include Sonic hedgehog homologue (Shh), a key developmental gene or possibly other genes involved in development of the respiratory tract
    • Other genes include:
      • Forkhead box (FOX) gene family
      • Sry-related HMG box (SOX) gene family
      • Zinc finger protein (GLI2)
Clinical features
  • Maternal hx of polyhydramniosis
  • Inability to swallow secretions
  • Inability to pass nasogastric tube
  • Laboured respiration
  • Coughing
  • Choking
  • VACTERL syndrome
  • (Cyanosis)
Pathophysiology
  • When oesophageal atresia is present, the infant is unable to swallow any liquid, including his or her own secretions
  • The baby cannot drink until either the atresia is repaired or the stomach is accessed via the anterior abdominal wall, or if a fistula is present, a connection between the airway and the alimentary tract
  • In type C, this connection can cause gaseous distension to form between the stomach and small bowel on x-ray
  • In rare cases, there is an associated intestinal atresia, which can lead to over-expansion and rupture of the stomach
  • Gastric contents can also reflux back through the fistula and cause aspiration, resulting in a chemical and bacterial pneumonitis
  • Motility of the oesophagus is always affected, with the distal segment having the most marked disordered peristalsis
  • There is also a lower resting pressure of the lower oesophageal sphincter resulting in a higher incidence of GORD
Investigations
  • Prenatal ultrasound
    • Polyhydramnios and a small or no stomach bubble
  • X-ray chest and abdomen
    • Nasogastric tube coiled in upper pouch 
  • Bronchoscopy
    • Presence of a fistula 
  • Oesophagoscopy
    • Presence of a fistula 
  • Barium swallow
    • Contrast in trachea
Management
  • The majority of patients require surgery to ligate the fistula and establish oesophageal continuity
  • The condition is not compatible with life as the patient cannot eat and is at significant risk for aspiration
  • Patients with pure atresia and no fistula also require surgery but can be managed either by direct gastric feeds or IV hyperalimentation with a delayed repair of the oesophagus
  • Type A
    • Surgical oesophageal repair at birth is often challenging
    • However, without a connection to the trachea, these patients are less susceptible to acute respiratory distress
    • First-line patients may be managed with a nasogastric tube in the upper oesophageal pouch, providing continuous suction
    • Within the first few days of life, a gastrostomy tube is placed to allow for enteral feeds and the stomach contrast study to identify the length of the lower pouch
    • Bronchoscopy is mandatory in cases of isolated atresia (gross A) to rule out an upper pouch fistula (10% -15% of cases)
    • If the length between the proximal and distal oesophageal segments is 4 vertebral bodies or longer, then the patient is allowed to grow prior to attempting a repair
    • Growth is monitored by using contrast radiographs
    • If the gap between the proximal and distal segments of the oesophagus is less than 2 vertebral bodies, primary oesophageal repair can be performed immediately or around 2 to 3 months of age
    • Standard therapy includes a right thoracotomy, although this procedure is now performed thoracoscopically
    • Thoracoscopic treatment is available in limited centres and only for experienced endoscopists
    • In cases of a very long gap, various techniques have been designed to stretch or increase the oesophageal length
    • In some cases of a failed oesophageal repair or an extremely long gap, oesophageal replacement surgery is planned.
  • Type B
    • These patients cannot eat and are at risk for repeated aspiration of oral secretions due to a proximal fistula
    • The patients can be managed initially by a suction catheter in the upper oesophageal pouch which should limit secretions going into the trachea
    • Surgery should take place in the first 24 to 48 hours of life to ligate and divide the fistula and establish oesophageal continuity
  • Type C
    • The first-line treatment is with surgical correction, aimed at dividing the tracheo-oesophageal fistula to prevent lung aspiration
    • Then, anastomosis of the 2 oesophageal ends is completed, in order to establish continuity of the oesophagus
    • Classically, this procedure has been performed via a right thoracotomy incision but is now performed in many centres using a thoracoscopic approach
      • Avoids the inherent morbidity of a thoracotomy
    • This operation should be performed within the first 24 hours of life to prevent complications of aspiration and abdominal distension
    • Before surgery, the patient is stabilized by placement of a nasogastric tube to decompress the upper blind pouch
  • Type D
    • This type is extremely rare and involves not only oesophageal atresia but fistulas in the proximal and distal pouches
    • A suction catheter should be placed prior to surgery to decompress the upper pouch and limit the secretions entering the trachea
    • Surgical management includes division of the fistulas and an anastomosis of the proximal and distal oesophageal pouches
  • Type E
    • These patients often present in late childhood or in early adulthood with evidence of choking, gagging or recurrent aspiration
    • Once diagnosed, the patient should be kept nothing by mouth until the fistula is divided
    • Through a right neck incision at the level of the thoracic inlet, fistula repair is performed
    • The fistula can also be reached thoracoscopically through the right chest
Prognosis
  • Patients with isolated tracheo-osophageal fistula without commonly associated congenital abnormalities (i.e., cardiac and chromosomal) have a good prognosis and survive to live healthy lives
  • Motility disorders and respiratory complications may occur
    • In one study, 58% of adults with infantile repair had GORD
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