Oesophageal Fistula

Also known as: Oesophago-tracheal fistula — Oesophago-bronchial fistula — Broncho-oesophageal fistula — Oesophago-pulmonary fistula

Introduction

An oesophageal fistula is an abnormal connection between the oesophageal lumen and a structure in its immediate vicinity, most commonly the lungs or other respiratory structures (producing a bronocho-oesophageal fistula). In rare cases, fistulae may be congenital but they are usually acquired phenomena. Acquired oesophageal fistulae occur when severe inflammation or disruption of the oesophageal wall leads to perforation and, as this heals, a tract is formed with the respiratory system. Causes of the initial insult include foreign bodies, neoplasia and severe oesophagitis. Passage of oesophageal luminal contents into the respiratory system may result in localised pneumonia, pleurisy and pulmonary abscessation.

Signalment

Cairn terriers may develop congenital fistulae but the condition is generally rare in cats and dogs.

Diagnosis

Clinical Signs

Clinical signs associated with congenital fistulae tend to develop after weaning as solid food is more likely to lodge in the fistula and, depending on the food, it may have a higher microbial load than milk. Acquired fistulae tend to develop later in life and are associated with an injury to the oesophagus. Clinical signs are usually associated with the respiratory system and gastro-intestinal signs are actually rare:

• Coughing, especially soon after eating or drinking.
• Dyspnoea
• Signs of (aspiration) pneumonia, including dyspnoea, tachypnoea, pyrexia and coughing.
• Signs of systemic illness, such as anorexia, lethargy and weight loss may occur due to severe chronic respiratory disease.
• Regurgitation occurs relatively uncommonly and may be associated with the initial cause of the inflammation, such as a foreign body.

Diagnostic Imaging

Plain radiographs of the chest may show localised areas with particular lung patterns (mainly alveolar with pneumonia but also bronchial and/or interstitial), mainly in the right caudal, right intermediate and left caudal lung lobes. The oesophagus usually appears normal unless a foreign body is visible as a radio-opaque mass within the lumen.

Administration of a positive contrast medium may be used to define the fistula and provide a definitive diagnosis. However, if barium is used, granulomas may form in the mediastinum or lungs whereas water soluble iodine-containing agents are irritant to the pulmonary parenchyma and may cause Pulmonary Oedema.

Endoscopy (oesophagoscopy) can also be used to provide a definitive diagnosis if the fistula is large enough to be visualised.

Treatment

Surgical repair of the fistula is required to prevent continued leakage of ingesta into the respiratory tract or mediastinum. An oesophagotomy incision is made to excise the fistula and the defect in the wall is then closed in a longitudinal orientation to reduce the risk of stricture formation. If one or more lobes of the lung are severely consolidated due to the presence of ingested material, these may be removed in a complete lobectomy. Any oesophageal foreign bodies should be removed.

Post-operatively, food should be withheld for 24-48 hours and the animal should receive only soft food thereafter. Sucralfate can be used to reduce any residual oesophagitis or ulceration and the patient should receive a full (4-6 week) course of antibiotics to clear any remaining respiratory infection. The choice of antibiotic should ideally be guided by culture of pulmonary fluid obtained during a lobectomy, if this is performed.

Possible complications include dehiscence of the surgical site, continued respiratory infection and persistent megaoesophagus if the fistula was left untreated for a prolonged period.

Prognosis

If surgical removal is successful, the prognosis is very good. If post-operative complications develop, the prognosis is guarded.

Oesophageal Fistula Learning Resources
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References

Ettinger, S.J, Feldman, E.C. (2005) Textbook of Veterinary Internal Medicine (6th edition, volume 2)

Hall, E.J, Simpson, J.W. and Williams, D.A. (2005) BSAVA Manual of Canine and Feline Gastroenterology (2nd Edition) BSAVA

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