gastrointestinal disorders
Crohn Disease
Diagnosis of Crohn Disease
Barium x-rays of the small bowel Abdominal CT (conventional or CT enterography) Sometimes barium enema, magnetic resonance (MR) enterography, upper endoscopy, colonoscopy, and/or video capsule endoscopy Crohn disease should be suspected in a patient with inflammatory or obstructive symptoms or in a patient without prominent GI symptoms but with perianal fistulas or abscesses or with otherwise unexplained arthritis, Erythema Nodosum , fever, anemia, or (in a child) stunted growth. A family history of Crohn disease also increases the index of suspicion. Similar symptoms and signs (eg, abdominal pain, diarrhea) may be caused by other GI disorders, particularly ulcerative colitis. Differentiating Crohn Disease and Ulcerative Colitis may be an issue in the 20% of cases in which Crohn disease is confined to the colon. However, because treatment is similar, this distinction is critical only when surgery or experimental therapy is contemplated. Patients presenting with an acute abdomen (either initially or during a relapse) should have an abdominal CT scan. These studies may show obstruction, abscesses or fistulas, and other possible causes of an acute abdomen (eg, appendicitis). Ultrasonography may better delineate gynecologic pathology in women with lower abdominal and pelvic pain. If initial presentation is less acute, an upper GI series with small-bowel follow-through and spot films of the terminal ileum is preferred over conventional CT. However, newer techniques of CT or MR enterography, which combine high-resolution CT or MR imaging with large volumes of ingested contrast, are becoming the procedures of choice in some centers. These imaging studies are virtually diagnostic if they show characteristic strictures or fistulas with accompanying separation of bowel loops. If findings are questionable, CT Enteroclysis or video capsule enteroscopy may show superficial aphthous and linear ulcers. Barium enema x-ray may be used if symptoms seem predominantly colonic (eg, diarrhea) and may show reflux of barium into the terminal ileum with irregularity, nodularity, stiffness, wall thickening, and a narrowed lumen. Differential diagnoses in patients with similar x-ray findings include cancer of the cecum, ileal carcinoid, In atypical cases (eg, predominantly diarrhea, with minimal pain), Diagnosis , with colonoscopy (including biopsy, sampling for enteric pathogens, and, when possible, visualization of the terminal ileum). Upper GI endoscopy may identify subtle gastroduodenal involvement even in the absence of upper GI symptoms. Laboratory tests should be done to screen for anemia, hypoalbuminemia, and electrolyte abnormalities. Liver tests should be done; elevated alkaline phosphatase and gamma–glutamyl transpeptidase levels in patients with major colonic involvement suggest possible primary sclerosing cholangitis. Leukocytosis or increased levels of acute-phase reactants (eg, erythrocyte sedimentation rate, C-reactive protein) are nonspecific but may be used serially to monitor disease activity. To detect nutritional deficiencies, levels ofvitamin Dand B12 should be checked every 1 to 2 years. Additional laboratory measurements, such as levels of water-soluble vitamins (folic acidandniacin), fat-soluble vitamins (A, D, E and K), and minerals (zinc,selenium, andcopper), may be checked when deficiencies are suspected. All patients with inflammatory bowel disease (IBD), whether male or female, young or old, should have their bone mineral density monitored, usually by Dual-energy x-ray absorptiometry (DXA) . Perinuclear antineutrophil cytoplasmic antibodies are present in 60 to 70% of patients with ulcerative colitis and in only 5 to 20% of patients with Crohn disease. Anti–Saccharomyces cerevisiaeantibodies are relatively specific for Crohn disease. However, these tests do not reliably separate the 2 diseases and they are not recommended for routine diagnosis. Additional antibodies such as anti-OmpC and anti-CBir1 are now available, but the clinical value of these supplementary tests is uncertain; some studies suggest that high titers of these antibodies have adverse prognostic implications. 