Also called
Terminal ileitis (If confined to terminal ileum)
ICD-10
K50.90
Specialty
Gastroenterology
Onset
Chronic
Reviewed
July 2026
On This Page
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OverviewOverview
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Etiology & Risk FactorsEtiology & Risk Factors
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PathophysiologyPathophysiology
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Clinical PresentationClinical Presentation
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History TakingHistory Taking
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Physical ExaminationPhysical Examination
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InvestigationsInvestigations
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DiagnosisDiagnosis
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ManagementManagement
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ComplicationsComplications
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PrognosisPrognosis
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Key Points / Clinical PearlsKey Points / Clinical Pearls
Overview of Crohn’s Disease
- Crohn’s disease is caused by abnormal immune system activity, although the exact cause is unknown.
- Some people may also develop problems outside the digestive system, such as inflammation of the eyes, joints, or skin.
Teaching point
Crohn’s disease is long-term but manageable with proper treatment and regular follow-up.
Etiology & Risk Factors
-Etiology of Crohn’s Disease
- The exact cause of Crohn’s disease is unknown.
- It is believed to result from abnormal immune system activity and an imbalance of normal gut bacteria, leading to chronic inflammation.
-Risk Factors for Crohn’s Disease
- Family history of Crohn’s disease
- Genetic predisposition (e.g., certain inherited genes)
- Smoking tobacco (the most important modifiable risk factor)
Pathophysiology of Crohn’s Disease
Immune dysregulation → Chronic intestinal inflammation → Edema + ulcers + tissue damage → Transmural (full-thickness) bowel inflammation → Fibrosis and scarring → Strictures/intestinal obstruction → Deep fissures → Abscess formation → Fistula formation
Clinical Presentation of Crohn’s Disease
- Chronic diarrhea
- Abdominal pain (usually in the right lower abdomen)
- Weight loss
- Fatigue
- Low-grade fever
- Loss of appetite
- Malabsorption (may cause anemia and poor growth in children)
- Perianal disease (fistulas, abscesses, or lesions)
- Blood in stool (less common)
- Extraintestinal manifestations:
- Joint pain/arthritis
- Eye inflammation (uveitis, episcleritis)
- Skin lesions (erythema nodosum, pyoderma gangrenosum)
- Mouth ulcers (oral aphthae)
Important Note
Smoking is the most important modifiable risk factor and can worsen the disease.
History Taking
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Ask about:
- When did your symptoms start?
- How often do you have diarrhea?
- Do you have abdominal pain? Where is it located?
- Have you noticed blood in your stool?
- Have you lost weight recently?
- Do you have fever or fatigue?
- Have you lost your appetite?
- Do you have nausea or vomiting?
- Do you have pain or drainage around the anus?
- Do you have mouth ulcers?
- Do you have joint pain, eye redness, or skin rashes?
- Do you smoke?
- Does anyone in your family have Crohn’s disease or inflammatory bowel disease?
- Have you had similar symptoms before?
- What medications are you taking?
Physical Examination
- Low-grade fever
- Weight loss or signs of malnutrition
- Right lower quadrant (RLQ) abdominal tenderness
- Palpable abdominal mass (sometimes)
- Perianal lesions (fissures, fistulas, abscesses, skin tags)
- Signs of dehydration (if severe diarrhea)
- Mouth ulcers (aphthous ulcers)
- Joint swelling or tenderness
- Eye redness/inflammation
- Skin lesions (erythema nodosum, pyoderma gangrenosum)
Investigations of Crohn’s Disease
-Laboratory tests
- CBC – anemia, infection
- CRP and ESR – assess inflammation
- Stool tests – rule out infection
- Fecal calprotectin – detects intestinal inflammation
-Endoscopy
- Ileocolonoscopy with biopsy – gold standard to confirm the diagnosis
-Imaging
- MR enterography (preferred) – assesses small bowel involvement
- CT abdomen – if complications (e.g., abscess, perforation) are suspected
-Biopsy findings
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- Transmural inflammation
- Noncaseating granulomas (when present)
Diagnosis of Crohn’s Disease
- Diagnosis is based on a combination of:
- Clinical symptoms (chronic diarrhea, abdominal pain, weight loss)
- Laboratory tests: ↑ CRP, ↑ fecal calprotectin
- Ileocolonoscopy with biopsy (gold standard)
- Endoscopic findings:
- Skip lesions
- Cobblestone appearance
- Ulcerations
- Imaging (MR enterography or CT): shows intestinal inflammation and extent of disease
Management of Crohn’s Disease
- Refer to a gastroenterologist.
- Smoking cessation.
- Nutritional support and correct vitamin/iron deficiencies.
- Acute flare:
- Mild disease: Budesonide
- Moderate to severe disease: Corticosteroids (e.g., prednisone)
- Severe disease: IV corticosteroids and hospitalization if needed
- Biologic therapy (e.g., anti-TNF agents such as infliximab or adalimumab) to induce and maintain remission.
- Immunomodulators (e.g., azathioprine, methotrexate) for maintenance therapy.
- Surgery for complications (e.g., bowel obstruction, fistulas, abscesses) or if medical treatment fails.
- Regular follow-up to monitor disease activity and complications.
Complications of Crohn’s Disease
- Strictures → bowel obstruction
- Fistulas (especially perianal)
- Abscess formation
- Intestinal perforation → peritonitis
- Malabsorption → weight loss, anemia, vitamin deficiencies
- Colorectal cancer (increased risk)
- Short bowel syndrome (after repeated surgery)
- Primary sclerosing cholangitis (PSC)
- Osteoporosis
Prognosis of Crohn’s Disease
- Chronic disease with no cure.
- Most patients have periods of relapse (flare-ups) and remission.
- Early diagnosis and treatment help reduce complications.
- Some patients eventually require surgery, but the disease can recur after surgery.
- Poorly controlled disease increases the risk of strictures, fistulas, and the need for surgery.
Key Points / Clinical Pearls of Crohn’s Disease
- Chronic inflammatory bowel disease (IBD) with no cure.
- Can affect any part of the gastrointestinal tract, especially the terminal ileum.
- Characterized by transmural (full-thickness) inflammation and skip lesions.
- Common symptoms: chronic diarrhea, abdominal pain, and weight loss.
- Smoking is the most important modifiable risk factor.
- Ileocolonoscopy with biopsy is the gold standard for diagnosis.
- Treatment aims to induce and maintain remission using medications such as corticosteroids, biologics, and immunomodulators.
- Surgery may be needed for complications, but the disease often recurs after surgery.
- Major complications: strictures, fistulas, abscesses, bowel obstruction, malabsorption, and increased risk of bowel cancer.
- Regular follow-up, medication adherence, and smoking cessation are essential for long-term disease control.
- Tian C, Ranasinghe IR, Hsu R. National Center for Biotechnology Information (NIH). Crohn Disease, StatPearls.
- ACG Clinical Guideline: Management of Crohn's Disease in Adults. Am J Gastroenterol. 2025. Guideline Central Summary.
- MedlinePlus, National Library of Medicine (NIH). Crohn's Disease: Health Topic.
- National Center for Biotechnology Information (NIH). Inflammatory Bowel Disease, StatPearls.
- National Center for Biotechnology Information (NIH). Cutaneous Crohn Disease, StatPearls.
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