Crohn’s disease, or: Morbus Crohn, is a chronic transmural inflammatory disease. Usually, this inflammatory bowel disease (IBD) affects the distal ileum and colon but may occur in any part of the gastrointestinal tract.
Symptoms include diarrhea and abdominal pain. Abscesses, internal and external fistulas, and bowel obstruction may arise. Extraintestinal symptoms, particularly arthritis, may occur. Diagnosis is by colonoscopy and barium contrast studies. Although Crohn’s disease and ulcerative colitis are similar, they can be distinguished in most cases.
Anti-Saccharomyces cerevisiae antibodies, ASCA, are relatively specific for Crohn’s disease. Testing for pANCA may be useful to distinguish between Crohn’s disease and ulcerative colitis, as pANCA are present in 60 to 70% of patients with ulcerative colitis and in only 5 to 20% of patients with Crohn’s disease. However, these tests do not reliably separate the two diseases.