Perianal fistulising Crohn disease in adults
Perianal fissures, fistulas and abscesses occur in up to 40% of patients with Crohn disease. Perianal Crohn disease should always be managed in consultation with a specialist colorectal surgeon; fistulas often need surgical exploration and local drainage, and placement of setons to prevent perianal sepsis.
Metronidazole or ciprofloxacin may be used to treat active perianal Crohn disease. Suitable regimens are:
1metronidazole 400 mg orally, 12-hourly metronidazole metronidazole metronidazole
OR
2ciprofloxacin 500 mg orally, 12-hourly1. ciprofloxacin ciprofloxacin ciprofloxacin
Therapy may be needed for weeks to months. If metronidazole is used long term, monitor patients for evidence of peripheral neuropathy.
Refractory perianal disease may respond to the addition of azathioprine; see Thiopurine therapy for maintenance management of Crohn disease for dosage.
Treatment with a tumour necrosis factor (TNF) inhibitor (eg adalimumab, infliximab) is indicated for the management of complex perianal fistula (eg trans-sphincteric, suprasphincteric, horseshoe or branching fistulae, or fistula with associated abscess or collections); refer to a gastroenterologist.