Complete Guide to Crohn’s Disease: Symptoms & Treatments

Crohn’s disease is a chronic, transmural inflammatory bowel disease (IBD) that can affect any part of the gastrointestinal (GI) tract, most commonly the terminal ileum and colon. Unlike ulcerative colitis, which is limited to the colon, Crohn disease is characterized by segmental “skip lesions,” where inflamed areas are sharply demarcated from adjacent healthy tissue. This autoimmune disorder causes inflammation across all layers of the bowel wall, leading to complications like strictures (narrowing), fistulas (abnormal tissue connections), and abscesses.

Pathophysiology

1. Inflammatory Mechanism:
   • Chronic inflammation spreads transmurally (through all bowel layers), causing tissue edema, ulceration, and fibrosis.
   • Granulomas: Noncaseating granulomas (clusters of immune cells) form in ~35–50% of patients but are not required for diagnosis. These granulomas signify chronic inflammation but do not predict disease severity.
   • Strictures: Over time, repeated inflammation and healing lead to scar tissue, narrowing the intestinal lumen and causing obstructive symptoms.
2. Anatomic Distribution:
   • Ileitis (30% of cases): Affects the ileum alone.
   • Ileocolitis (40%): Involves both the ileum and colon, often sparing the rectum.
   • Colonic (30%): Limited to the colon.
   • Rarely affects the stomach, duodenum, or esophagus.
3. Genetic and Environmental Factors:
   • Genetics: Mutations in genes like NOD2 (CARD15) increase susceptibility.
   • Smoking: A major modifiable risk factor linked to disease progression and post-surgical recurrence, especially in women.

Crohn’s disease Symptoms and Signs

Primary Symptoms:

Perianal fistulas/abscesses (25–33% of patients).

Chronic diarrhea (often non-bloody).

Abdominal pain and cramps (worsens after meals).

Fatigue, weight loss, fever, and malnutrition.

• Complications:
  • Bowel Obstruction: Caused by strictures or adhesions.
  • Fistulas: Entero-enteric (bowel-to-bowel), entero-vesical (bowel-to-bladder), or perianal.
  • Malabsorption: Leading to deficiencies in vitamin B₁₂, iron, or fat-soluble vitamins.
  • Extraintestinal Manifestations: Arthritis, erythema nodosum, uveitis, or primary sclerosing cholangitis.
• Red Flags: Sudden worsening of symptoms, severe abdominal pain, or rectal bleeding (less common than in ulcerative colitis).

Crohn’s Disease Bleeding

Crohn’s-related intestinal inflammation can erode blood vessels, causing gastrointestinal (GI) bleeding. Symptoms include blood in stool (hematochezia) or black, tarry stools (melena). Severe bleeding is uncommon but may require urgent treatment, such as endoscopy or surgery. Bleeding risk is higher in colonic Crohn’s than small-bowel disease.

Crohn’s Disease With Constipation

Constipation with Crohn’s signals potential strictures, adhesions, or bowel obstruction. Contrast with typical Crohn’s diarrhea patterns. Imaging (CT/MR enterography) identifies structural issues. Treatment includes dietary adjustments (low-residue), laxatives, or surgical resection if obstructions develop.

Crohn’s disease Diagnosis

1. Clinical Evaluation:
   • Detailed history of symptoms, family history of IBD, and smoking status.
2. Imaging:
   • CT/MRI Enterography: Detects bowel-wall thickening, strictures, or fistulas.
   • Small-Bowel Follow-Through: Highlights cobblestone mucosa and strictures (“string sign”).
   • Colonoscopy with Biopsy: Gold standard for diagnosis by colonoscopy; reveals patchy inflammation, ulcers, or granulomas.
3. Laboratory Tests:
   • Blood: Elevated CRP, ESR, or anemia (iron/B₁₂ deficiency).
   • Stool: Calprotectin (marker of intestinal inflammation), infectious workup to rule out pathogens.
4. Differential Diagnoses:
   • Ulcerative colitis, intestinal tuberculosis, celiac disease, or NSAID-induced enteropathy.

Crohn’s disease Treatments

1. Mild to Moderate Disease:

• Corticosteroids: Budesonide (9 mg/day) targets ileocecal inflammation with fewer systemic side effects than prednisone.
• 5-ASA Agents (e.g., mesalamine): Limited efficacy for small-bowel disease but used in colonic involvement.
• Antibiotics (e.g., metronidazole): For perianal fistulas or bacterial overgrowth.

2. Moderate to Severe Disease:

• Immunosuppressants:
  • Thiopurines (azathioprine, 6-mercaptopurine) reduce relapse rates post-surgery.
  • Methotrexate (for steroid-refractory cases).
• Biologic Therapies:
  • Anti-TNF Agents (infliximab, adalimumab): Induce remission in fistulizing/severe disease.
  • Anti-Integrins (vedolizumab): Gut-specific therapy with fewer systemic risks.
  • IL-12/23 Inhibitors (ustekinumab): For TNF-refractory patients.

3. Surgery:

• Indications: Obstruction, fistulas, abscesses, or medically refractory disease.
• Procedures: Strictureplasty (widens narrowed areas), resection of affected bowel.
• Post-Surgical Risks: High recurrence rates (50% at 10 years); mitigated by early thiopurine or biologic therapy.

4. Lifestyle and Supportive Care:

• Diet: Low-residue diet for strictures; avoid NSAIDs and smoking.
• Nutritional Supplements: Vitamin D, calcium, iron, or B₁₂.

Crohn’s disease Prognosis and Complications

• Disease Course: Chronic, relapsing-remitting pattern; >75% require surgery.
• Cancer Risk: Elevated risk of colorectal cancer in long-standing colonic disease.
• Mortality: Most deaths are due to thromboembolism or cancer.

Key References

1. Dulai PS et al. (2019). Should we divide Crohn’s disease into ileum-dominant and isolated colonic diseases?
2. Gomollón F et al. (2017). 3rd European Crohn’s and Colitis Organisation Consensus on Diagnosis and Management.
3. Feuerstein JD et al. (2021). ACG Clinical Guideline for Crohn’s Disease Management.

Conclusion

Crohn disease requires a tailored approach combining aggressive medical therapy, surgical intervention for complications, and lifestyle modifications. Advances in biologics and personalized medicine continue to improve quality of life, though early diagnosis and multidisciplinary care remain critical to reducing long-term morbidity.