Gastrolab/Science Source
This patient's clinical presentation and laboratory findings are consistent with a diagnosis of Crohn disease.
Crohn disease is a chronic inflammatory bowel disease that is becoming increasingly prevalent worldwide. It is estimated to affect three to 20 persons per 100,000. When not effectively managed, Crohn disease is associated with substantial morbidity and significant impairments in lifestyle and daily activities during flares and remissions. It is characterized by a transmural granulomatous inflammation that can affect any part of the gastrointestinal tract — usually, the ileum, colon, or both.
Abdominal pain, diarrhea, weight loss, and fatigue are often prominent symptoms in patients with Crohn disease. Crampy or steady right lower quadrant or periumbilical pain may develop; the pain both precedes and may be partially relieved by defecation. Diarrhea is frequently intermittent and is not usually grossly bloody. Diffuse abdominal pain accompanied by mucus, blood, and pus in the stool may be reported by patients if the colon is involved. Involvement of the small intestine usually presents with evidence of malabsorption, including diarrhea, abdominal pain, weight loss, and anorexia, which may be subtle early in the disease course. Anorexia, nausea, and vomiting are more common in patients with gastroduodenal involvement, whereas debilitating perirectal pain, malodorous discharge from a fistula, and disfiguring scars from active disease or previous surgery may be present in patients with perianal disease. Patients may also present with symptoms suggestive of intestinal obstruction, or with anemia, recurrent fistulas, or fever.
As stated in guidelines from the American Gastroenterological Association (AGA), multiple streams of information, including history and physical examination, laboratory tests, endoscopy results, pathology findings, and radiographic tests, must be incorporated to arrive at a clinical diagnosis of Crohn disease. In most cases, the presence of chronic intestinal inflammation solidifies a diagnosis of Crohn disease. However, it can be challenging to differentiate Crohn disease from ulcerative colitis, particularly when the inflammation is confined to the colon. Bleeding is much more common in ulcerative colitis than in Crohn disease, whereas intestinal obstruction is common in Crohn disease and uncommon in ulcerative colitis. Fistulae and perianal disease are common in Crohn disease but are absent or rare in ulcerative colitis. Moreover, weight loss is typical in patients with Crohn disease but is uncommon in ulcerative colitis.
Additional diagnostic clues for Crohn disease include discontinuous involvement with skip areas; sparing of the rectum; deep, linear, or serpiginous ulcers of the colon; strictures; fistulas; or granulomatous inflammation. Only a small percentage of patients have granulomas on biopsy. The presence of ileitis in a patient with extensive colitis (ie, backwash ileitis) can also make determining the inflammatory bowel disease subtype challenging.
Arthropathy (both axial and peripheral) is a classic extraintestinal manifestation of Crohn disease, as are dermatologic manifestations (including pyoderma gangrenosum and erythema nodosum); ocular manifestations (including uveitis, scleritis, and episcleritis); and hepatobiliary disease (ie, primary sclerosing cholangitis). Less common extraintestinal complications of Crohn disease include:
• Thromboembolism (both venous and arterial)
• Metabolic bone diseases
• Osteonecrosis
• Cholelithiasis
• Nephrolithiasis.
Only 20%-30% of patients with Crohn disease will have a nonprogressive or indolent course. Clinical features that are associated with a high risk for progressive disease burden include young age at diagnosis, initial extensive bowel involvement, ileal or ileocolonic involvement, perianal or severe rectal disease, and a penetrating or stenosis disease phenotype.
According to the AGA's Clinical Care Pathway for Crohn Disease, clinical laboratory testing in a patient with symptoms of Crohn disease should include:
• Complete blood cell count (anemia and leukocytosis are the most common abnormalities seen)
• C-reactive protein (not a specific marker, but may correlate with disease activity in a subset of patients)
• Comprehensive metabolic panel
• Fecal calprotectin (may correlate with intestinal inflammation; can help distinguish inflammatory bowel disorders from irritable bowel syndrome)
• Erythrocyte sedimentation rate (may be elevated in some patients; not a specific marker)
Ileocolonoscopy with biopsies should be performed in the evaluation of patients with suspected Crohn disease, and disease distribution and severity should be documented at the time of diagnosis. Biopsies of uninvolved mucosa are recommended to identify the extent of histologic disease.
Consult the AGA guidelines for more extensive details on the workup for Crohn disease, including indications for additional imaging and phenotypic classification.
In recent years, outcomes in Crohn disease have improved, which is probably the result of earlier diagnosis, increasing use of biologics, escalation or alteration of therapy based on disease severity, and endoscopic management of colorectal cancer. As noted above, Crohn disease includes multiple phenotypes, characterized by the Montreal Classification as stricturing, penetrating, inflammatory (nonstricturing and nonpenetrating), and perianal disease. Each of these phenotypes can present with a range in severity from mild to severe disease.
In general, therapeutic recommendations for patients are based on disease location, disease severity, disease-associated complications, and future disease prognosis and are individualized according to the symptomatic response and tolerance. Current therapeutic approaches should be considered a sequential continuum to treat acute disease or induce clinical remission, then maintain response or remission. Pharmacologic options include antidiarrheal agents, anti-inflammatory therapies (eg, sulfasalazine, mesalamine), corticosteroids (a short course for severe disease), biologic therapies (eg, infliximab, adalimumab, certolizumab pegol, natalizumab, vedolizumab, ustekinumab), and occasionally immunosuppressive agents (tacrolimus, mycophenolate mofetil). In addition to their 2014 guidelines on the management of Crohn disease in adults, the AGA recently released guidelines specific to the medical management of moderate to severe luminal and fistulizing Crohn disease.
Bhupinder S. Anand, MD, Professor, Department of Medicine, Baylor College of Medicine, Houston, TX
Bhupinder S. Anand, MD, has disclosed no relevant financial relationships