Inflammatory Bowel Disease: Crohn's Disease vs Ulcerative Colitis

Inflammatory bowel disease (IBD) is a high-yield topic on nursing exams because students must reliably distinguish Crohn's disease from ulcerative colitis (UC) and recognize their unique complications, drug therapies, and nursing priorities. This guide organizes the key comparisons and clinical actions you need to know.

What Is Inflammatory Bowel Disease?

• IBD is a chronic inflammatory condition of the gastrointestinal tract.
• The two main types are Crohn's disease and ulcerative colitis.
• Both result from an abnormal immune response to gut bacteria in genetically susceptible individuals.

Crohn's Disease vs Ulcerative Colitis

Pathophysiology

• Crohn's disease: transmural inflammation with skip lesions and fistulas.
• Ulcerative colitis: continuous mucosal inflammation that begins at the rectum.

Clinical Presentation

• Crohn's disease: non-bloody diarrhea, right lower quadrant pain, weight loss, and perianal fistulas.
• Ulcerative colitis: bloody diarrhea, left lower quadrant pain, tenesmus, and urgency.
• Extraintestinal manifestations (both): erythema nodosum, pyoderma gangrenosum, uveitis, arthritis, and primary sclerosing cholangitis (associated with UC).

Diagnostic Tests

• Colonoscopy with biopsy is the gold standard.
• Granulomas on biopsy → Crohn's disease.
• Crypt abscesses on biopsy → ulcerative colitis.

Complications

• Crohn's disease: fistulas, strictures, abscesses, and malabsorption.
• Ulcerative colitis: toxic megacolon, massive hemorrhage, perforation, and significantly increased colorectal cancer risk after 8–10 years.

Medications

• Sulfasalazine causes orange urine and reversible oligospermia.
• Infliximab requires tuberculosis screening and may cause infusion reactions.

Management of an Acute Flare (First Actions)

• Administer aggressive IV fluids for dehydration.
• Administer corticosteroids for moderate to severe inflammation.
• Monitor for toxic megacolon: abdominal distension, fever, and decreased bowel sounds.

Nursing Priorities

• Monitor bowel movements for frequency, consistency, and blood.
• Monitor for dehydration: dry mucous membranes, hypotension.
• Monitor for toxic megacolon: abdominal distension, fever, decreased bowel sounds.
• For patients with strictures, provide a low-fiber, low-residue diet.
• For severe flares, maintain NPO status and insert a nasogastric tube if obstruction is present.

Patient Teaching

• Take medications exactly as prescribed; do not stop them during flares.
• Avoid NSAIDs — they worsen IBD.
• Avoid trigger foods during flares: dairy, spicy foods, and high-fiber foods.
• Patients with UC need colonoscopy surveillance every 1–3 years after 8 years of disease.

Surgery

• Surgery for Crohn's disease is not curative — the disease recurs at the anastomosis site.
• Total proctocolectomy with ileal pouch-anal anastomosis is curative for ulcerative colitis.

Common Exam Traps

• Crohn's = non-bloody diarrhea; UC = bloody diarrhea.
• Smoking worsens Crohn's but may improve UC.
• Sulfasalazine → orange urine and reversible oligospermia.
• Infliximab → TB screening required before initiation.
• Toxic megacolon is a complication of UC, not Crohn's.
• Surgery is curative for UC but not for Crohn's.

Key takeaways

• Crohn's: transmural, skip lesions, non-bloody diarrhea, RLQ pain, fistulas, granulomas on biopsy.
• UC: continuous mucosal inflammation from the rectum, bloody diarrhea, LLQ pain, crypt abscesses on biopsy.
• First priority in an acute flare: IV fluids and corticosteroids; monitor for toxic megacolon.
• 5-ASAs are first-line for UC; biologics require TB screening before starting.
• Avoid NSAIDs; UC patients require colorectal cancer surveillance after 8 years of disease.
• Surgery is curative for UC but not for Crohn's disease.