CROHN DISEASE 30A
A 28-year-old woman arrives in the urgent care clinic complaining of cramping abdominal pain. She has had the pain intermittently over the past 5 months, accompanied by diarrhea. During this time period, she lost 16 lb and had significant malaise. On examination, she has a diffusely tender abdomen, worst in the right lower quadrant (RLQ), but no rebound or guarding. Complete blood count (CBC) reveals anemia, and her serum vitamin B12 level is low. Her stool culture and ova and parasites examination results are negative. She is referred for colonoscopy, partly to exclude inflammatory bowel disease (IBD).
What are the salient features of this patient’s problem? How do you think through her problem?
Salient features: Chronic cramping abdominal pain and diarrhea; weight loss; malaise; anemia (presumably from poor vitamin B12 absorption in the terminal ileum); negative stool test results
How to think through: Diarrhea, a common symptom, requires consideration of its time course and a framework for clinical reasoning to determine its cause. This patient has chronic diarrhea. In chronic diarrhea, what are the common pathologic categories to frame the differential diagnosis? (Common causes: infectious, inflammatory, functional, malabsorption, and medication side effects. Less common causes: vasculitis, neuroendocrine tumors; may be explored after the common causes.) What characteristics make IBD likely in this patient? (Chronic abdominal pain; weight loss; and low serum vitamin B12 level, indicating possible involvement of the terminal ileum). Is fecal leukocyte testing useful in diagnosis of IBD? (No. Test specificity is poor; fecal leukocytes also occur in infectious diarrhea.) What extraintestinal symptoms and signs would increase your suspicion for IBD? (Fever, uveitis, arthritis, oral ulcers, erythema nodosum.) Ulcerative colitis commonly causes hematochezia, and Crohn disease causes heme-positive stools without gross blood. Her anemia may be caused by anemia of chronic disease, iron deficiency from gastrointestinal blood loss, or vitamin B12 deficiency. Do the gross and pathologic colonoscopic findings differ between Crohn disease and ulcerative colitis? (Yes.) What are the most serious complications of Crohn disease? (Fistulae, intraabdominal abscesses, and intestinal obstruction.) What are the common steroid-sparing agents used in the treatment of Crohn disease? (Azathioprine; mercaptopurine; methotrexate; infliximab.)
CROHN DISEASE 30B
What are the essentials of diagnosis and general considerations regarding Crohn disease?
Essentials of Diagnosis
Insidious onset of intermittent bouts of low-grade fever, diarrhea, and RLQ pain
Radiographic evidence of ulceration, stricturing, or fistulas of the small intestine or colon
General Considerations
Crohn disease is a transmural process.
Crohn disease may involve the small bowel only, colon alone, or both; it is most common in the terminal ileum.
It is a chronic illness with exacerbations and remissions.
One-third of patients have associated perianal disease (fistulas, fissures, abscesses).
Fewer than 5% of patients have symptomatic involvement of the upper intestinal tract.
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