Colorectal Quiz Episode 26: Perianal Crohn's Disease

When the colonoscope cannot intubate the terminal ileum, capsule endoscopy or fecal calprotectin can be used to aid diagnosis.

If terminal ileum cannot be intubated, gastroenterologists may treat presumptively and re-scope after a few months of treatment when inflammation has decreased.

Real risks of biologic agents include infectious complications such as tuberculosis and risk of lymphoma.

The highest risk factors for lymphoma with biologic therapy are male gender, teenage age, and combination therapy with methotrexate.

It is common to have perianal disease in Crohn's; this patient had a delay in diagnosis and had perianal disease for quite some time with multiple skin tags and fissures.

Male gender over the age of 10, and presence of a fistula are risk factors with much higher incidence of Crohn's disease being diagnosed in patients presenting with perianal lesions to the emergency room.

In pediatric patients, unlike adult patients, the first presenting factor for Crohn's disease can often be perianal disease.

The mucosa heals first compared to skin in perianal disease, so leaving a mucosal opening without a seton risks recurrent abscess when biologics heal the mucosa.

Making a large cruciate incision and packing a perianal abscess in a child with undiagnosed Crohn's disease may result in non-healing and potentially require colostomy or ileostomy.

Hydrogen peroxide is preferred over methylene blue for identifying fistula tracts because it is neater; 3% hydrogen peroxide in a syringe with 16-20 gauge angiocath is used with a speculum in the anus.

When a fistula opening cannot be found despite hydrogen peroxide testing, a seton should not be placed at that time to avoid creating a hole where there isn't one.

Source control of infection must be achieved before starting immunosuppressive therapy including steroids and biologics.

If an abscess is not adequately drained, reimaging should be performed before giving biologics or steroids.

Setons should remain in place for at least 6 months to allow the inflammatory tract to become non-inflammatory.

For recurrent patients requiring repeat seton placement, repeat imaging should be obtained before seton removal.

Literature shows about a 10% response rate for perianal fistulas even without biologics if a seton is placed and removed, with much better outcomes with biologics.

Before removing a seton, the bottom must look better, drainage must be better, the patient must be symptom-free, and they must have reached steady state of biologic (loading dose plus at least 3 more doses, typically 2-3 months from start).

Inflammatory markers including fecal calprotectin, ESR, and CRP should be checked before removing a seton to ensure systemic disease is under control.

Remicade (infliximab) has the most literature on healing perianal disease; Humira also has good evidence but less literature; Stelara and vedolizumab are sometimes used with less information available.

The initial Remicade paper from 1998 or 1999 in the New England Journal of Medicine was on perianal disease and demonstrated improved healing time and improved length of time between recurrence when combination of seton and infliximab is used versus either separately.