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For further information, see CMDT Part 15-35: Inflammatory Bowel Disease

Key Features

Essentials of Diagnosis

  • Insidious onset

  • Intermittent bouts of low-grade fever, diarrhea, and right lower quadrant pain

  • Right lower quadrant mass and tenderness

  • Perianal disease with fistulas, fissures, and abscesses

  • Radiographic or endoscopic evidence of ulceration, stricturing, or fistulas of the small intestine or colon

General Considerations

  • Crohn disease is a transmural process

  • Crohn disease may involve

    • Small bowel only, most commonly the terminal ileum (ileitis) in ~33% of cases

    • Small bowel and colon, most often the terminal ileum and adjacent proximal ascending colon (ileocolitis) in ~50%

    • Colon alone in 20%

  • Chronic illness with exacerbations and remissions

  • One-third of patients have associated perianal disease (fistulas, fissures, abscesses)

  • Less than 5% patients have symptomatic involvement of the upper intestinal tract

  • Smokers are at increased risk

  • Treatment is directed both toward symptomatic improvement and controlling the disease process

Clinical Findings

Symptoms and Signs

  • Abdominal pain

  • Liquid bowel movements

  • Abdominal tenderness or abdominal mass

Luminal inflammatory disease

  • Most common presentation at diagnosis (60–80%)

  • Malaise, loss of energy

  • Diarrhea, nonbloody, intermittent

  • Cramping or steady right lower quadrant or periumbilical pain

  • Focal tenderness, right lower quadrant

  • Palpable, tender mass in the lower abdomen

Intestinal stricturing

  • Postprandial bloating, cramping pains, and loud borborygmi

  • Narrowing of the small bowel may occur as a result of inflammation or fibrotic stenosis

Fistulization with or without infection

  • Sinus tracts and fistulas can result in intra-abdominal or retroperitoneal abscesses manifested by fevers, chills, tender abdominal mass, and leukocytosis

  • Fistulas between the small intestine and colon commonly are asymptomatic but can result in diarrhea, weight loss, bacterial overgrowth, and malnutrition

  • Bladder or vaginal recurrent infections

  • Cutaneous fistulas

  • Perianal disease

    • Skin tags

    • Anal fissures

    • Perianal abscesses

    • Fistulas

Extraintestinal manifestations

  • Arthralgias, arthritis

  • Iritis or uveitis

  • Pyoderma gangrenosum

  • Erythema nodosum

  • Oral aphthous lesions

  • Gallstones

  • Nephrolithiasis with stones

Differential Diagnosis

  • Ulcerative colitis

  • Irritable bowel syndrome

  • Appendicitis

  • Yersinia enterocolitica enteritis

  • Mesenteric adenitis

  • Intestinal lymphoma

  • Segmental colitis due to ischemic colitis, tuberculosis, amebiasis, chlamydia

  • Diverticulitis or appendicitis with abscess

  • Nonsteroidal anti-inflammatory drug–induced colitis

  • Perianal fistula due to other cause


Laboratory Tests

  • Obtain complete blood count, erythrocyte sedimentation rate or C-reactive protein, serum albumin

    • Anemia may be due to chronic inflammation, blood loss, iron deficiency, or vitamin B12 malabsorption

    • Leukocytosis occurs with abscesses

    • Sedimentation rate or C-reactive protein elevated

  • Fecal calprotectin

    • An excellent noninvasive test

    • Elevated levels are correlated with active inflammation as seen on ileocolonoscopy or radiologic CT or MR enterography

  • Stool specimens are sent ...

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