Crohn Fistula

Crohn fistulas result from transmural inflammation penetrating into adjacent bowel, bladder, vagina, skin or other structures.

Common abdominal fistulas include:

• Enteroenteric
• Enterocolic
• Enterovesical
• Enterovaginal
• Enterocutaneous

A radiological fistula alone is not necessarily an indication for surgery. The indication is driven by symptoms, sepsis, obstruction, malabsorption and the anatomy of the diseased donor segment.

Enteroenteric fistulas may remain asymptomatic.

Enterocolic fistulas can bypass substantial absorptive bowel and cause diarrhoea or malnutrition.

Enterovesical fistulas produce pneumaturia, recurrent urinary infection and faecaluria.

Enterovaginal fistulas cause passage of enteric material or gas through the vagina.

Fistulas associated with fever, focal pain or systemic inflammation should be assumed to have an associated abscess until excluded.

MR enterography: preferred for elective definition of fistula anatomy and associated luminal Crohn disease.

CT abdomen: better suited to acute sepsis and abscess.

Define the diseased segment that created the fistula, the target organ and whether obstruction or abscess coexists.

Control sepsis before definitive reconstruction.

Drain associated abscesses and optimise nutrition.

Asymptomatic enteroenteric fistulas without obstruction or malabsorption can sometimes be observed during medical treatment.

Surgery becomes appropriate with:

• Enterovesical fistula
• Significant enterovaginal fistula
• Associated stricture
• Associated abscess
• Persistent sepsis
• Malabsorption from bypass
• Symptomatic enterocutaneous fistula
• Medically refractory disease.

At surgery, resect the diseased Crohn segment that created the fistula. The target organ may need only limited repair if otherwise healthy.

For an enterovesical fistula, limited bladder closure is sufficient when a clear bladder defect remains after bowel separation. Extensive bladder resection is unnecessary unless the bladder itself is diseased.

Avoid en bloc removal of healthy adjacent organs simply because they are adherent to penetrating Crohn disease.

Temporary diversion may be appropriate when there is severe sepsis, poor tissue quality, malnutrition or high anastomotic risk.