[JNUS]

Crohn disease was first described in 1932 by Crohn, Ginzberg, and Oppenheimer, who noted its localization to segments of the ileum. Crohn disease is a chronic granulomatous inflammatory process that can involve any part of the gastrointestinal tract. Though the exact pathogenesis of the disease is unknown, the condition is believed to be caused by an imbalance between proinflammatory and anti-inflammatory mediators, leading to autoimmune destruction of the mucosal cells. The characteristic presentation of Crohn disease is variable, but it is frequently associated with abdominal pain, diarrhea, weight loss, and anorexia. Unpredictable flare-ups and remissions characterize the long-term course of the disease.

Because the inflammatory process is transmural and depending on the area of inflammation, the condition may be complicated by intestinal fistulization, obstruction, or both; these complications are more common in Crohn disease than in ulcerative colitis. Up to 30 % of patients will develop fistulas or abscesses, most commonly in the perianal region.4 When fistulas develop, they usually connect the ileum, sigmoid colon, or the cecum, but they also may be enterovesical, enterovaginal, or enterocutaneous. The presentation and associated complications from fistulas are variable. Cologastric fistulas manifest as feculent vomiting, whereas enterovesical fistulas manifest as recurrent urinary tract infections and pneumaturia; enterovaginal fistulas manifest as feculent vaginal discharge; and enterocutaneous fistulas manifest as feculent soiling of the skin. Coloenteric and cologastric fistulas may result in bacterial overgrowth, diarrhea, and weight loss. Enterovesical fistulas and enterovaginal fistulas are often complicated by infection, including cystitis, abscess formation, and peritonitis. Enterocutaneous fistulas frequently develop at a former surgical site.

Multiple imaging techniques can be used to establish the diagnosis of fistulous disease. Barium contrast studies can identify features such as strictures, fistulization, and submucosal edema. The fistulas can be detected by oral barium fluoroscopy or through barium injection into the opening of the suspected fistula. Computed tomography (CT) scanning using oral and rectal contrast agents can also be helpful in diagnosing and delineating fistulas, and it has the added benefit of detecting local abscess formation, hepatobiliary complications, and renal complications. MRI is also useful in detecting fistulas, and it can be superior to CT in demonstrating pelvic lesions.

Treatment of Crohn fistulas is aimed at reducing inflammation and controlling symptoms. Fistulas between bowel loops may be benign but may also cause diarrhea with malabsorption and malnutrition. Enterovesicular, enterocutaneous, cologastric, and coloduodenal fistulas are more serious. Surgical intervention is rarely required, unless fistulas are complicated by progressive obstruction or abscess formation or a large segment of bowel is bypassed, leading to severe diarrhea and malabsorption.3 Sulfasalazine (3-4 g daily) or mesalamine (4 g daily) can be used to treat bowel disease. In cases of moderate to severe disease, steroids, such as prednisone (60 mg daily), can be used. Oral metronidazole (1 g daily for 1-2 months) can also effectively treat fistulous disease. Immunosuppressive drugs, such as 6-mercaptopurine or azathioprine, are beneficial in reducing drainage and closing fistulas in 30-40% of patients.3 Additionally, prolonged bowel rest with total parenteral nutrition can be helpful in promoting healing of fistulas; they may recur when oral feeding resumes.

The patient in this case was admitted to the hospital and received a combination treatment regimen of oral prednisone, azathioprine, and metronidazole. Over the following 2 weeks, the discharge from the enterocutaneous fistula transitioned from purulent material to a more serous and feculent discharge. Conservative medical management was determined to be adequate for long-term therapy, and the patient was discharged to home.