Gastric Fistula

A gastric fistula is an abnormal communication between the gastric lumen and another epithelial surface or organ.

It may communicate with:

• Skin, producing a gastrocutaneous fistula
• Colon, producing a gastrocolic fistula
• Small bowel
• Pleural or thoracic cavity
• Another portion of the stomach

Most clinically important postoperative fistulas evolve from a gastric staple line, anastomotic or perforation leak that fails to heal and becomes a chronic epithelialised tract.

Common settings include sleeve gastrectomy, gastrectomy, gastrojejunostomy, oesophagogastric surgery, trauma, malignancy and chronic peptic disease.

A leak is an acute transmural defect. A fistula is usually a more mature pathological communication between epithelialised surfaces.

Acute postoperative leakage may present before a mature fistula forms.

Important features include:

• Persistent tachycardia
• Fever
• Left upper abdominal or shoulder pain
• Sepsis
• Purulent or gastric drain output
• Enteric material from the wound
• Failure to tolerate oral intake

A chronic gastrocutaneous fistula may present with persistent acidic gastric drainage through the abdominal wall, causing severe skin excoriation and fluid loss.

A gastrocolic fistula can produce diarrhoea, weight loss, malnutrition, foul eructation or faeculent vomiting.

Persistent tachycardia after upper gastrointestinal surgery should never be dismissed simply because abdominal examination is mild.

CT abdomen with oral and IV contrast: define the fistula or leak, associated collection and whether there is distal obstruction.

Upper gastrointestinal endoscopy: defines the internal opening and allows therapeutic intervention.

A contrast study may help delineate anatomy in a chronic external fistula.

Assess full blood count, renal function, electrolytes, magnesium, phosphate and nutritional status. Measure external fistula output daily.

The most important diagnostic questions are:

• Is there uncontrolled sepsis?
• Is there a drainable collection?
• Is there distal obstruction?
• Is the defect acute or chronic?
• Is surrounding tissue viable?

These determine whether closure is likely to succeed.

Management begins with source control and physiological recovery, not immediate closure of the fistula.

Sepsis and collections

Keep fasting initially when an uncontrolled acute leak is present.

Drain associated collections percutaneously, endoscopically or surgically according to anatomy.

For significant postoperative gastric sepsis:

Piperacillin tazobactam 4.5 g IV every 8 hours by extended infusion, adjusted for renal function.

Use culture results to narrow therapy.

Prolonged antibiotics are not a substitute for drainage.

Give acid suppression, for example:

Pantoprazole 40 mg IV or orally every 12 hours during active high output gastric leakage.

Nutrition

Nutrition is central to fistula healing.

Use enteral feeding distal to the fistula whenever feasible, such as nasojejunal or feeding jejunostomy nutrition.

Use parenteral nutrition when enteral feeding cannot adequately meet requirements or markedly increases fistula output.

Correct magnesium, phosphate, potassium and micronutrient deficiencies aggressively.

Protect surrounding skin from acidic gastric effluent.

Endoscopic treatment

Endoscopic therapy has become central to postoperative gastric leaks and fistulas. Choice depends on defect size, chronicity, associated cavity and tissue quality.

Clips: best for small fresh defects with healthy pliable margins.

An over the scope clip provides stronger full thickness closure than standard clips and is useful for selected small fistula openings.

Endoscopic suturing: useful for larger defects when tissue can be approximated without excessive tension.

Fully covered self expanding stent: diverts luminal contents across selected acute leaks, particularly proximal gastric and oesophagogastric defects.

Stent migration is a major limitation.

Endoscopic internal drainage: useful when a contained perigastric cavity can be drained internally into the gastric lumen.

Endoscopic vacuum therapy: particularly effective for leaks associated with infected cavities. A sponge or vacuum device is positioned within the defect or cavity and exchanged serially, promoting drainage and granulation.

Chronic epithelialised fistulas are harder to close than fresh leaks because the tract has matured. De epithelialisation or tract preparation may be required before clipping or suturing.

Surgery

Operate when there is:

• Generalised peritonitis
• Haemodynamic instability
• Uncontrolled sepsis despite drainage
• Gastric necrosis
• Large uncontained disruption
• Distal mechanical obstruction preventing healing
• Failed appropriate endoscopic therapy
• Chronic fistula with anatomy unsuitable for minimally invasive closure

Definitive surgery may require fistula tract excision, gastric resection, revision of the original anastomosis or reconstruction.

Do not perform repeated closure attempts without correcting distal obstruction, uncontrolled infection or severe malnutrition. These are major reasons fistulas fail to heal.