Diagnosis and Treatment of Perianal Fistulas in Crohn’s Disease
Abstract & Commentary
Synopsis: Crohn’s disease is commonly associated with perianal fistulas (43%), and there have been great ad-vances both in the diagnosis and therapy of this noxious illness.
Source: Schwartz DA, et al. Ann Intern Med. 2001;135:906-918.
Primary care physicians may be first to identify perianal fistulas, sometimes the presenting feature of Crohn’s disease, and it is appropriate for internists and family physicians to be aware of advances in this area of gastroenterologic medicine.
Perianal fistulas, which present in up to 43% of Crohn’s patients, can be studied effectively using such modern imaging modalities as MRI scanning or endoanal ultrasonography. Treatment currently may entail antibiotics such as metronidazole and ciprofloxacin. Immunosuppression with azathioprine or 6-mercaptopurine (6-MP) both have been successfully used for fistulous Crohn’s disease, and the newest approaches involve intravenous administration of antitumor necrosis factor-a antibody (infliximab) or parenteral cyclosporine. Surgical treatment often begins with abscess drainage, placement of noncutting setons, or fistulotomy. Combination medical and surgical therapy often is required. It is extremely important that patients with complicated fistulous disease associated with Crohn’s be referred to gastroenterologists and general or colorectal surgeons with extensive experience in managing this condition.
Comment by Malcolm Robinson, MD, FACP, FACG
This excellent article is "must" reading for any physician who might encounter Crohn’s disease patients with fistulas. Since many patients with fistulas are first evaluated by primary care physicians, this report may be useful for a wide range of clinicians. There have been some dramatic advances in the diagnosis of this illness, and fistulography, endoscopy, physical examination, and even examination under anesthesia are no longer necessarily sufficiently precise to define the extent of this pathological process. For example, MRI results have been shown to be superior to those of examination under anesthesia (and also better than fistulography or CT scanning). Endorectal ultrasonography may be as accurate as MRI when a skilled endosonographer is available. Fistulas are classified as superficial, intersphincteric, and transsphincteric. Metronidazole is often used initially as medical therapy for Crohn’s fistulas, and 6-MP has led to doubling of resolution of fistulas vs. placebo. Even better results have been demonstrated with infliximab and cyclosporine—although both of these agents should only be used by clinicians highly familiar with their administration. Although TPN and elemental diets have been recommended for fistula management, they are not recommended as part of primary therapy for fistulas. Superficial fistulas often respond to fistulotomy, but extensive and complicated fistulous disease usually should be treated with conservative surgical measures such as seton placement for continued effective drainage. In the past, diversion of the fecal stream was recommended for management of severe fistulous Crohn’s disease. This has been largely abandoned since it is almost never possible to restore bowel continuity in these instances.
Dr. Robinson, Medical Director, Oklahoma Foundation for Digestive Research; Clinical Professor of Medicine, University of Oklahoma College of Medicine, Oklahoma City, OK, is Associate Editor of Internal Medicine Alert.
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