Small Bowel Fistulae: Five Cases and Current Lessons

This article is an educational review of surgical cases. It is not personal medical advice and should not be used as a substitute for care by qualified clinicians. Current management of enterocutaneous fistulae requires individualized assessment by surgical, nutrition, wound/stoma, interventional radiology, infectious disease, and intestinal-failure specialists when available.

Introduction

Intestinal fistulae are abnormal communications involving the gastrointestinal tract. Internal fistulae communicate with another viscus, while external enterocutaneous fistulae drain onto the skin or into an open wound. Enterocutaneous fistulae can cause major fluid, electrolyte, and nutrient losses, with dehydration, metabolic derangement, sepsis, malnutrition, wound injury, organ failure, and death in severe cases (Pepe et al., 2024; Tang et al., 2020).

Modern management classifies enterocutaneous fistulae partly by output: low output is generally less than 200 mL/day, moderate output is 200-500 mL/day, and high output is more than 500 mL/day (Ghimire, 2022; Cowan and Cassaro, 2023). Output matters because high-output fistulae are more likely to cause dehydration, electrolyte imbalance, malnutrition, and intestinal failure, and they often require parenteral nutrition or combined nutritional support (Couper et al., 2021; Kumpf et al., 2017).

The dogma that symptomatic internal fistulae “all” require operative repair is too absolute. Symptomatic internal fistulae require evaluation for sepsis, malignancy, Crohn disease or other inflammatory bowel disease, distal obstruction, nutritional compromise, and fistula anatomy; many ultimately need operative, endoscopic, interventional, oncologic, or disease-specific therapy, but timing and approach should be individualized (Ghimire, 2022; Cowan and Cassaro, 2023).

For external fistulae, contemporary care is usually organized around structured frameworks such as SNAP: sepsis and skin control, nutrition, anatomy definition, and a plan for definitive management (Tang et al., 2020). The related SOWATS framework emphasizes sepsis control, optimization of nutrition, wound care, anatomy, timing of surgery, and surgical planning (Ghimire, 2022). These frameworks update the traditional idea that management depends mainly on “good judgement” by providing a safer, reproducible sequence of priorities.

Over five months, two surgical services had seven cases of intestinal fistulae. Two were internal, one associated with an underlying colonic malignancy and the other with ileocolic Crohn’s disease. Both internal fistulae were treated by resection and anastomosis and both did well. The remaining five were postoperative external small-bowel fistulae and are discussed below.

Cases

Case I

This 41-year-old man attended a private hospital with a bleeding duodenal ulcer confirmed on endoscopy. He underwent truncal vagotomy and pyloroplasty but rebled ten days later. He then underwent partial gastrectomy and Billroth II reconstruction. Nine days after gastric resection, he developed a low-output duodenal fistula and was transferred to the University Hospital, where he received seven days of parenteral nutrition averaging 2,000 calories per day. His fistula closed spontaneously after nine days.

This outcome is consistent with the current understanding that low-output fistulae, controlled sepsis, favorable anatomy, and absence of distal obstruction increase the likelihood of spontaneous closure (Cowan and Cassaro, 2023). Today, the nutrition route would be individualized after fluid and electrolyte stabilization: oral or enteral nutrition may be feasible in low-output enterocutaneous fistulae when no distal obstruction is present, while parenteral nutrition may be needed if output, obstruction, intolerance, or wound/skin compromise prevents adequate enteral support (Kumpf et al., 2017).

Case II

This 41-year-old woman had two previous Caesarean sections followed by hysterectomy and incidental appendectomy. She attended a rural hospital with lower abdominal pain and an ultrasonographically detected right ovarian cyst. She underwent laparotomy with lysis of adhesions and right ovarian cystectomy. Injured small bowel was resected, anastomosed, and repaired. Postoperatively, she developed intestinal obstruction and underwent relaparotomy on day 8 with lysis of adhesions and repair of new small-bowel injuries. She was treated for pneumonia postoperatively. Six days after relaparotomy, she was noted to have a wound infection and a distal ileal fistula. She was transferred to the University Hospital, tolerated an adequate oral diet, and the fistula closed spontaneously within 11 days.

This case illustrates an important current principle: the gut should be used when it is safe and functional, but oral or enteral feeding depends on fistula location, output, remaining functional bowel, distal obstruction, metabolic stability, and whether feeds increase output or worsen nutritional status (Couper et al., 2021). If oral or enteral feeding fails to meet needs, worsens metabolic derangements, or does not maintain or improve nutrition status, supplemental or full parenteral nutrition is required (Couper et al., 2021).

Case III

Forty-five-year-old L.S. had laparotomy at a rural hospital, where he was found to have a perforated duodenal ulcer with severe intra-abdominal infection. Abscesses were drained and the perforated ulcer was patched. Postoperatively, he developed respiratory failure with right lung consolidation and collapse. He was transferred to the University Hospital for ventilatory support after tracheostomy. Five days after laparotomy, he developed abdomen wound dehiscence and a duodenal fistula. The duodenal fistula could not easily be exposed, so a sump drain was placed in the right upper quadrant and the abdominal incision was re-sutured.

Fluid and electrolyte balance was maintained and parenteral nutrition was given for 39 days at an average of 1,920 calories per day. The patient later developed bilateral subclavian vein thrombosis and parenteral nutrition was discontinued. High fistulous drainage persisted. At laparotomy six weeks after admission, he was noted to have a duodenal fistula, two jejunal fistulae, and a transverse colon fistula draining into a common tract. The duodenal fistula was intubated. The two fistulated loops of jejunum were mobilized, the lateral fistulae were closed, and the loops were laid away from the fistulous tract. The transverse colon fistula was exteriorized in the incision. An inadvertent laceration to the jejunum was repaired, and a distal jejunostomy was sited with a feeding jejunostomy catheter brought out to one side of the incision.

After six days of enteral nutrition, intestinal fistulae recurred. Jejunostomy feeds refluxed through the fistulae and enteral nutrition was discontinued. The incision disrupted and the deep fistulae were treated by an open laparostomy approach. Nine days later, the severely malnourished patient died.

This patient had a complex fistula in the setting of severe sepsis, open abdomen, malnutrition, high output, failed enteral access, and vascular-access complications. Open abdomen and enteroatmospheric fistula management now emphasize effluent isolation, wound and skin protection, sepsis control, nutritional support, and careful avoidance of direct bowel trauma from drains, suction, dressing changes, or negative pressure systems (Pepe et al., 2024). Negative pressure wound therapy may help selected patients, but it must be tailored and bowel-protective because direct application over bowel can increase the risk of bowel injury, ischemia, necrosis, or new fistula formation (Pepe et al., 2024).

Parenteral nutrition may be lifesaving in high-output or obstructed fistulae, but central venous catheter infection and thrombosis are major hazards. Current practice involves early nutritional support and securing vascular access with expertise, daily fluid and electrolyte replacement, sepsis surveillance, and referral to a center with expertise for the management of intestinal failure for complex or chronic cases (Kumpf et al., 2017; Pironi et al., 2023).

Case IV

One year before presentation, this 56-year-old man had large-bowel obstruction for which he underwent sigmoid colostomy and subsequent closure. On his recent admission, he had recurrence of presumptive rectosigmoid obstruction. A sigmoid colostomy was refashioned and injured small bowel was repaired. Eleven days later he had relaparotomy for intestinal obstruction. The small bowel was again injured and repaired, and an obstructed small-bowel loop was bypassed. Four days later he developed a low-output ileal fistula with wound disruption. He was then transferred to the University Hospital, where he received parenteral nutrition supplemented by oral feeding. After 28 days, the ileal fistula closed spontaneously, only to be followed three days later by a jejunoatmospheric fistula in the granulating wound.

After 52 days of parenteral nutrition averaging 2,800 calories per day and 36 days of jejunostomy and oral supplementation, the jejunal fistula had failed to close over 11 weeks. There had also been one documented episode of central venous catheter sepsis. At the time of the report, the patient remained on the surgical floor receiving jejunostomy and oral feeds.

The concern then that this fistula was unlikely to close remains well supported. Unfavorable features for spontaneous closure include an enteric defect greater than 1 cm, everted or budding mucosa, short tract, high output, disrupted continuity, distal obstruction, adjacent abscess, diseased bowel, foreign body, previous radiation, malnutrition, and ongoing sepsis (Pepe et al., 2024; Ghimire, 2022). FRIEND factors are also used to summarize barriers to closure: foreign body, radiation, inflammation or infection, epithelialization, neoplasm, and distal obstruction (Cowan and Cassaro, 2023).

The current recommendations are first to define the anatomy and cause of recurrent obstruction using cross-sectional imaging, contrast studies, and endoscopy as clinically appropriate. Fistulography and CT with contrast can help identify the tract, abscesses, distal obstruction, foreign bodies, and the amount and quality of downstream bowel (Cowan and Cassaro, 2023; Ghimire, 2022).

The previous expectation that repair could occur as early as four weeks after resolution of infection should be revised. Contemporary intestinal-failure surgery literature emphasizes delaying elective reconstruction until sepsis has resolved, nutrition has improved, anatomy is defined, and the abdomen is suitable; a systematic review found wide timing variation but concluded that optimal timing is probably 6-12 months after the last laparotomy, while spontaneous closure is most likely in low-output fistulae within 3-6 months (de Vries et al., 2018). Urgent or earlier surgery remains appropriate for uncontrolled sepsis, obstruction, hemorrhage, inability to control effluent, or other life-threatening complications.

Case V

This 48-year-old man attended hospital with generalized peritonitis. At operation, his appendix was removed, but ten days later he developed septic shock with generalized suppurative peritonitis and a blown appendix stump. At relaparotomy, a tube cecostomy was sited. His intra-abdominal sepsis persisted and he developed a cecal fistula. At relaparotomy six days later, he underwent right hemicolectomy with ileotransverse anastomosis. Injured small bowel was repaired and right upper quadrant and pelvic drains were placed. One week later, he had partial wound dehiscence, wound infection, and a high-output intestinal fistula. Two weeks after the fistula was diagnosed, he was transferred to the University Hospital. Parenteral nutrition lasted 29 days with an average daily delivery of 2,000 calories, supplemented by a high-protein, high-calorie oral diet. One month after admission, he began bleeding via the fistula and also had gastrointestinal bleeding. He was transfused and remained stable, but high fistulous drainage persisted. Two days later, he was found pulseless. A postmortem examination was not performed.

This case highlights the danger of uncontrolled intra-abdominal sepsis, high-output fistula, and possible hemorrhage from vessel erosion. Current reviews emphasize aggressive resuscitation, rapid correction of electrolyte abnormalities, drainage of abscesses or other septic foci, wound and skin protection, and nutritional support before definitive reconstruction when possible (Ghimire, 2022; Tang et al., 2020). In uncontrolled sepsis, diversion or exteriorization may be safer than a primary anastomosis, with definitive reconstruction delayed until the patient is optimized (Ghimire, 2022).

Bleeding through a fistula should be treated as a life-threatening event requiring resuscitation, localization of bleeding with imaging, endoscopy, or CT angiography as appropriate, and source control by interventional radiology or surgery depending on anatomy and stability (Ghimire, 2022).

Discussion

Surgical injury, hostile abdomen, and systems lessons

These five cases describe repeated laparotomies, dense adhesions, severe peritonitis, sepsis, bowel obstruction, and inadvertent bowel injuries. Rather than attributing every injury solely to individual technical error, a modern patient-safety framing recognizes that postoperative enterocutaneous fistulae commonly arise from anastomotic leak or unrecognized bowel injury, especially in hostile abdomens with adhesions, malignancy, inflammatory bowel disease, trauma, sepsis, or repeat operations (Ghimire, 2022; Pepe et al., 2024).

The practical lesson remains important: each reoperation in an inflamed abdomen increases the risk of bowel injury, fistula formation, abscess, and recurrent sepsis. Current surgical planning therefore emphasizes source control, avoiding unnecessary reoperation during the hostile inflammatory phase, defining anatomy before reconstruction, and delaying elective fistula takedown until the patient is physiologically and nutritionally optimized (de Vries et al., 2018).

Nutrition and fluid replacement

Nutrition is central to fistula care, but “enteral whenever possible” must be interpreted carefully. ASPEN-FELANPE recommends nutrition assessment at diagnosis and periodic reassessment because fistula patients have a high likelihood of malnutrition from nutrient malabsorption, fluid and electrolyte losses, and sepsis (Kumpf et al., 2017). The same guideline states that, after fluid and electrolyte stabilization, oral diet or enteral nutrition may be feasible in low-output fistulae without distal obstruction, while high-output fistulae may require parenteral nutrition to meet fluid, electrolyte, and nutrient requirements (Kumpf et al., 2017).

High-output fistulae require meticulous replacement of fluid, sodium, potassium, magnesium, bicarbonate, and protein losses, with urine output, weight, renal function, and serum electrolytes monitored closely. Contemporary reviews also support acid suppression, antimotility therapy, and selected use of somatostatin analogues to reduce output, while noting that these measures are adjuncts rather than substitutes for sepsis control, nutrition, and definition of anatomy (Ghimire, 2022; Cowan and Cassaro, 2023).

Wound, effluent, and open-abdomen care

Wound and effluent control are not minor supportive tasks; they determine whether nutrition, mobilization, infection control, skin preservation, and later reconstruction are possible. Excess effluent can damage skin, contaminate the wound, worsen fluid and electrolyte loss, and prevent healing (Pepe et al., 2024). Specialized stoma and wound care, fistula isolation devices, controlled drainage, skin barriers, and carefully selected negative pressure wound therapy can simplify care and protect the wound, but negative pressure systems must be applied with attention to bowel protection and fistula anatomy (Pepe et al., 2024).

Timing of surgery

The most important update to the management of small bowel fistulae is timing. Elective definitive repair should not be driven only by elapsed weeks after infection appears controlled. It should follow resolution of sepsis, nutritional recovery, correction of fluid and electrolyte abnormalities, wound control, clear definition of fistula anatomy, and an operative plan that accounts for abdominal wall reconstruction and recurrence risk (de Vries et al., 2018; Ghimire, 2022).

A systematic review and meta-analysis of intestinal-failure surgery found that fistula recurrence varied widely and that no single optimal timing could be defined, but it also noted that specialized centers generally postpone reconstructive surgery and suggested that optimal timing is probably 6-12 months after the last laparotomy (de Vries et al., 2018). This does not mean that all patients wait the same interval. Uncontrolled sepsis, uncontrolled effluent, obstruction, ischemia, or hemorrhage may require urgent intervention.

Conclusion

These five cases teach important lessons. Small-bowel fistulae are not managed by one intervention alone; they require stabilization, sepsis control, wound and effluent management, nutritional support, anatomy definition, and carefully timed surgery. Oral or enteral nutrition should be used when feasible and safe, while parenteral nutrition is necessary when high output, obstruction, intolerance, or metabolic instability prevent adequate enteral support (Kumpf et al., 2017; Couper et al., 2021).

For complex, high-output, open-abdomen, or chronic fistulae, outcomes are likely to improve when care is coordinated by multidisciplinary teams with experience in intestinal failure, nutritional support, wound and stoma care, vascular access, interventional radiology, and delayed reconstructive surgery (Pironi et al., 2023; Pepe et al., 2024).

Acknowledgement: Dr. Hugh Barned assisted with the review of the patients above.

References

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