Fistulas

A fistula is an abnormal connection between two epithelium-lined surfaces. The most common fistulas are enteroenteric fistula, enterovesical fistula, rectovaginal fistula, cholecystoenteric fistula, pancreatic fistula, and urogenital fistula. Fistulas are most commonly caused by local inflammation (e.g., diverticulitis, Crohn disease, pancreatitis), malignancy (e.g., colon cancer, rectal cancer), or iatrogenic injury (e.g., resulting from prolonged labor, abdominal or pelvic surgery, radiation). Clinical features depend on the location of the fistula, e.g., enteroenteric, enterovesical, and pancreatic fistulas cause abdominal pain and diarrhea. Some fistulas (e.g., enterovesical, vesicovaginal, rectovaginal, and enterocutaneous fistulas) cause leakage of fluid from the connected organ. Diagnosis for most fistulas is made via abdominal or pelvic CT. Treatment most commonly consists of fistula resection, although conservative management may be indicated for certain fistulas (e.g., choledochoduodenal and pancreatic fistulas).

For more information on vascular fistulas, see “Arteriovenous fistulas;” for more information on tracheoesophageal fistula, see “Esophageal atresia;” and for more information on anal fistulas, see “Anal abscess and fistula."

Enteroenteric fistula

• Definition: an abnormal connection between two parts of the bowel
• Etiology
  • Iatrogenic
    • A complication of open abdominal surgery: usually caused by procedures during which bowel is frequently manipulated or by disruption of bowel anastomosis, inadvertent enterotomy, or small bowel injury
    • Irradiation
  • Inflammatory bowel disease (IBD): Crohn disease, ulcerative colitis
  • GI disorders: e.g., complicated diverticulitis, acute appendicitis, gastrointestinal tuberculosis, peptic ulcer disease
  • Malignancy: e.g., colorectal cancer, gastric cancer
  • Foreign body ingestion
  • Trauma
• Pathophysiology: deficient anastomoses/sutures, improper healing following intervention (e.g., radiation), or trauma → leakage of intestinal contents → local infection → abscess formation and/or erosion → intestinal epithelial defect → epithelial cells penetrating into deeper layers of the mucosa → formation of a tube-like structure → tube connecting to other organs or the body surface (fistula formation) ^[1]
• Types
  • Coloenteric fistula: an abnormal connection between the colon and the small bowel (most commonly located at the terminal ileum)
  • Gastrocolic fistula: an abnormal connection between the stomach and the colon
• Clinical features
  • Coloenteric fistula ^[2]
    • Sudden and severe watery diarrhea
    • Abdominal pain
    • Weight loss
    • Physical examination might show a palpable abdominal mass.
  • Gastrocolic fistula ^[3]
    • Abdominal pain
    • Vomiting (may be feculent), foul‑smelling belching
    • Diarrhea
    • Weight loss
• Diagnostics ^[4]
  • CT abdomen and pelvis: to diagnose suspected coloenteric fistula
  • Colonoscopy: to rule out malignancy as the cause of fistula (malignant fistula)
  • Barium enema: preferred test for diagnosing gastrocolic fistula ^[3]
• Treatment: resection of fistula and reanastamosis of healthy bowel
• Complications
  • Infection, sepsis
  • Fluid and electrolyte abnormalities
  • Malnutrition
• Prognosis: recurrence may occur (∼ 36% of cases) ^[5]

Enterocutaneous fistula

• Definition: an abnormal connection between the small or large bowel and the skin
• Etiology
  • Iatrogenic: e.g., abdominal surgery, percutaneous drainage, radiation
  • Inflammation: e.g., Crohn disease, gastrointestinal tuberculosis
  • Malignancy: e.g., colorectal cancer
  • Foreign body ingestion
  • Trauma
• Subtype
  • Enteroatmospheric fistula
    • An abnormal communication between the lumen of the GI tract and the external atmosphere (e.g., via an open abdominal wound)
    • Most commonly occurs as a complication of abdominal surgery (e.g., laparotomy during which the abdomen is left open to prevent abdominal compartment syndrome)
  • See also “Fistulizing Crohn disease.”
• Clinical features ^[1]
  • Abdominal pain
  • Nausea, vomiting
  • Obstipation
  • Induration of the abdominal wall, drainage of intestinal content through the skin
  • Possibly fever
• Management ^[6][7]
  • Stabilization (24–48 hours)
    • Fluid/electrolyte replacement
      • Fluid correction with normal saline or ringer lactate
      • Electrolyte and acid-base disturbances correction (e.g., hypokalemia, hypomagnesemia, metabolic acidosis)
    • Identification and control of infection; (e.g, sepsis, peritonitis, surgical site infection)
      • Antibiotic therapy
      • If applicable, source control via percutaneous drainage or surgical exploration for intraabdominal abscess, fluid collection, or peritonitis
    • Complete bowel rest and nutritional management (based on fistula output and length of functional bowel) ^[6]
      • Low- and medium-output fistulas < 0.5 L/24 hours: oral nutrition or enteral nutrition
      • High-output fistulas > 0.5 L/24 hours: parenteral nutrition; substitute with enteral nutrition if the patient tolerates it
    • Wound management
      • Ostomy pouch or negative pressure wound therapy
      • Local skincare (e.g., barrier creams, ostomy appliances)
      • Agents to reduce fistula output (e.g., antidiarrheal agents, somatostatin)
  • Fistula and bowel anatomy assessment (after 7–10 days)
    • CT scan, fistulogram, and/or enteroscopy: shows anatomy of the fistula and detects possible intraabdominal abscess, fluid collections, and/or intestinal obstructions
    • Biochemical analysis of ECF fluid (e.g., ↑ bilirubin)
  • Surgical planning (after 7–10 days to 4–6 weeks)
    • Assess the likelihood of nonoperative closure (spontaneous closure occurs in at least 30% of patients) ^[8]
    • Plan therapeutic course and operative approach
  • Operative treatment (> 4–6 weeks)
    • Endoscopic or surgical repair
    • Indicated if fistula does not close sufficiently (e.g., complex fistulas, high-output fistulas) after approx. 3 months of conservative treatment

Optimized nutritional support is associated with higher fistula closure rates and lower mortality. ^[6]

Enterovesical fistula

• Definition: an abnormal connection between the bladder and bowel (e.g., colon, rectum)
• Etiology
  • Congenital: e.g., failure of the urorectal septum to develop
  • Acquired
    • Inflammation: e.g., diverticulitis, Crohn disease
    • Cancer: e.g., colon cancer
    • Radiation
    • Trauma
• Pathophysiology: fistula between bladder and bowel → direct spread of intestinal bacteria to the bladder → recurrent UTIs
• Subtype: colovesical fistula (a fistula between the colon and bladder)
• Clinical features
  • Pneumaturia: passing of air in the urine
  • Fecaluria: passing of stool in the urine
  • Recurrent UTIs and urosepsis: suprapubic pain, dysuria, urgency, frequency, possibly hematuria
• Diagnostics
  • CT abdomen with oral contrast ^[9]
    • Localized thickening of the colon and bladder
    • Air or collection of radiocontrast in the bladder
  • Urinalysis
    • Pyuria and bacteriuria
    • Signs of fecaluria (e.g., undigested muscle fibers) ^[10]
• Management
  • Resection and primary anastomosis
  • Antibiotics if surgery is not possible

Rectovaginal fistula

• Definition: an abnormal connection between the rectum and the vagina
• Etiology
  • Most commonly obstetric complications
    • Prolonged labor
    • Episiotomy
    • Failed repair of a perineal laceration
    • Injury during vaginal delivery
  • Less common
    • Crohn disease, diverticulitis
    • Radiation
    • Colon cancer
    • Fecal impaction
• Clinical features
  • Very small rectovaginal fistulas are often asymptomatic.
  • Uncontrollable passage of gas and/or feces from the vagina
  • Malodorous vaginal discharge
• Diagnostics
  • Vaginal examination (with speculum or even colposcopy)
  • Methylene blue dye can help to identify the fistula tract.
  • Endoanal ultrasound: to rule out concomitant anal sphincter defects
• Differential diagnosis
  • Anal fistula
  • Perianal abscess
  • Anal incontinence
  • Vaginal infection (e.g., chlamydia)
• Treatment
  • Transvaginal, transanal, transsphincteric, or transverse transperineal fistulectomy (with or without graft or tissue interposition)
  • In patients with concomitant sphincter injury: sphincter repair and reconstruction of the perineal body and rectovaginal septum

Cholecystoenteric fistula ^[11][12][13]

• Definition: an abnormal connection between the gallbladder lumen and the lumen of the adjacent bowel (usually stomach or duodenum)
• Etiology
  • Most commonly: gallbladder perforation or pressure necrosis from a large gallstone
  • Rarely: acute cholecystitis, gallbladder carcinoma (neoplastic infiltration)
• Clinical features ^[14]
  • Potentially asymptomatic
  • Bile acid diarrhea
  • Can manifest as cholangitis (e.g., fever, pain, jaundice)
  • Gallstone ileus, which may manifest as:
    • Mechanical bowel obstruction (obstruction is often located at the ileocecal valve)
    • Bouveret syndrome: gastric outlet obstruction secondary to impaction of a gallstone in the pylorus or proximal duodenum ^[15]
• Diagnostics
  • Imaging ^[14]
    • Air within the biliary tree (pneumobilia)
    • Fistulous tract between the gallbladder (typically the fundus) and the adjacent bowel
  • Upper GI barium enema: no contrast in the colon
• Management
  • Patients with cholangitis: empiric antibiotic therapy for biliary infection (combination regimen), laparoscopic cholecystectomy, and closure of the fistula ^[16]
  • Patients with gallstone ileus: enterolithotomy with or without cholecystectomy and closure of the fistula (see ''Treatment'' in “Gallstone ileus”) ^[17][18]

Choledochoduodenal fistula ^[19]

• Definition: an abnormal connection between the common bile duct and the duodenum
• Etiology: cholelithiasis, duodenal ulcer, and tumors (e.g., gallbladder carcinoma)
• Clinical features: symptoms of cholangitis (e.g., fever, pain, jaundice)
• Diagnostics
  • Imaging: pneumobilia
  • GI barium studies: opacification of bile ducts
  • CT abdomen: fistula with duodenal narrowing
  • Endoscopy: to rule out malignancy
• Management
  • Primarily conservative: e.g., antiulcer therapy (see “Treatment of peptic ulcer disease”)
  • Surgery is only recommended in refractory cases.

• Definition: an abnormal connection between the pancreas and adjacent or distant organs, structures, or spaces (e.g., pleural cavity)
  • Internal pancreatic fistula: pancreatic duct connects to the peritoneal cavity, pleural cavity, or hollow viscus
  • External pancreatic fistula: pancreatic duct connects to the skin
• Etiology
  • Acute or chronic pancreatitis
  • Pancreatic resection
  • Percutaneous drainage of pancreatic pseudocyst or pancreatic abscess
  • Abdominal trauma
• Pathophysiology: disruption of pancreatic duct → leakage of pancreatic fluid → erosion of neighboring structures, dehydration, malnutrition, and possibly infection
• Clinical features
  • Internal pancreatic fistula
    • Can be asymptomatic
    • Common symptoms include abdominal pain/distention (due to ascites), nausea, vomiting, diarrhea
    • Possibly GI bleeding
    • In severe cases: weight loss, anorexia, weakness
  • External pancreatic fistula: drainage of pancreatic fluid from an abdominal wound
  • Both
    • Signs of dehydration and malnutrition
    • In cases of infection: fever
• Diagnostics
  • Imaging (e.g., CT abdomen)
    • Fluid collections in abdominal and/or thoracic cavity
    • Signs of acute or chronic pancreatitis (e.g., edematous swelling)
  • Laboratory tests: Fluid analysis from drainage of an external fistula shows increased pancreatic fluid amylase. ^[20]
• Management
  • Conservative management ^[21]
    • Nil per os to reduce pancreatic stimulation
    • Nasojejunal feeding to correct malnutrition
    • Correction of fluid and electrolyte disturbances
    • Somatostatin analogs (e.g., octreotide) to reduce fistula output
    • Skin care in external pancreatic fistulas
    • Antibiotics in cases of infection
  • Endoscopic therapy (pancreatic stent placement) if conservative treatment fails
  • Surgery (e.g., pancreaticojejunostomy) if endoscopic treatment fails
• Complications
  • Dehydration, malnutrition
  • Erosion of neighboring structures, skin excoriation
  • Infection, sepsis