How is crohn's disease diagnosed?

How Is Crohn's Disease Diagnosed?

Crohn's disease is a type of inflammatory bowel disease (IBD) that can affect any part of the digestive tract. Because its symptoms—such as abdominal pain, diarrhea, fatigue and weight loss—overlap with other conditions, a careful diagnostic process is essential. Here's how doctors typically confirm a diagnosis of Crohn's disease, based on current evidence and expert guidelines (Gomollon et al. 2017).

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1. Medical History & Physical Examination

A thorough history and exam help guide which tests to order:

• Review of symptoms

  • Abdominal cramping or pain
  • Persistent diarrhea (sometimes with blood)
  • Unintended weight loss
  • Fatigue, fever or joint pain

• Risk factors & family history

  • Personal or family history of IBD
  • Smoking status (smoking can worsen Crohn's)
  • Medication-use history (some drugs can mimic IBD)

• Physical exam

  • Abdomen palpation to detect tenderness or mass
  • Assessment for extra-intestinal signs (skin rashes, eye redness, joint swelling)

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2. Laboratory Tests

Blood and stool tests help rule out infections and measure inflammation.

Blood Tests

• Complete blood count (CBC)

  • Anemia (low red blood cells) from chronic bleeding
  • Elevated white blood cells indicating inflammation

• Inflammatory markers

  • C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) often rise in active Crohn's

• Nutritional deficiencies

  • Low iron, vitamin B12 or vitamin D levels if parts of the intestine aren't absorbing properly

Stool Tests

• Infection screen

  • Rule out bacterial, viral or parasitic causes of diarrhea

• Faecal calprotectin

  • A protein released by inflamed intestinal cells
  • High levels suggest IBD rather than a functional bowel disorder (van Rheenen et al. 2010)

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3. Endoscopic Evaluation & Biopsy

Direct visualization of the bowel and tissue sampling are the gold standard for diagnosing Crohn's disease.

Colonoscopy (Ileocolonoscopy)

• Allows examination of the colon and terminal ileum
• Typical findings:
  • Patchy "skip" lesions (areas of normal bowel between inflamed sections)
  • Ulcers, strictures or narrowing
• Biopsy (small tissue samples) is taken throughout
  • Confirms chronic inflammation
  • Helps rule out infections, cancer or other conditions

Upper Endoscopy (Gastroscopy)

• Examines the esophagus, stomach and duodenum when upper-GI symptoms exist
• Can detect Crohn's involvement in the upper digestive tract

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4. Imaging Studies

Imaging helps evaluate disease extent, complications (fistulas, abscesses, strictures) and small-bowel involvement that endoscopy can't reach.

CT Enterography

• Uses oral contrast and CT scanning for detailed small-bowel images
• Detects wall thickening, ulcers, strictures, abscesses
• High accuracy for active inflammation (Paulsen et al. 2012)

MR Enterography

• Similar to CT enterography but uses MRI, avoiding radiation exposure
• Excellent for assessing disease activity, fistulas and perianal disease
• Preferred in children and young adults when frequent imaging is needed

Abdominal Ultrasound

• Non-invasive, no radiation
• Operator-dependent but increasingly used to monitor bowel wall thickness and blood flow

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5. Other Tests (When Needed)

• Capsule Endoscopy

  • A swallowed camera pill takes images throughout the small intestine
  • Useful if CT/MR findings are inconclusive and endoscopy can't reach high-small bowel areas

• Double-Balloon or Single-Balloon Enteroscopy

  • Specialized endoscopic methods to examine or biopsy deep small-bowel areas

• Small-Bowel Follow-Through (Barium X-ray)

  • Traditional imaging using oral barium contrast
  • Less common now but may be used where advanced imaging isn't available

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6. Putting It All Together

Diagnosing Crohn's disease involves integrating all the above findings:

• Clinical presentation and symptom pattern
• Lab tests indicating inflammation
• Endoscopic appearance and biopsy results
• Imaging that defines disease location and severity

This comprehensive approach ensures accurate diagnosis and helps form the basis for an individualized treatment plan.

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What to Do Next

If you've been experiencing persistent gastrointestinal symptoms like abdominal pain, diarrhea or unexplained weight loss, Ubie's free AI symptom checker can help you understand whether your symptoms may be related to Crohn's disease and guide you on the next steps to take.

However, tests and online tools can't replace medical advice. Always speak to a doctor about anything that could be life-threatening or serious. Early diagnosis and treatment can help manage symptoms, reduce complications and improve quality of life.