Crohn's Disease

Crohn's disease is a chronic inflammatory bowel disease (IBD) that causes inflammation of the digestive tract. This inflammation can affect any part of the gastrointestinal tract from the mouth to the anus, but most commonly affects the end of the small intestine (ileum) and the beginning of the colon. The inflammation often spreads deep into affected tissues, causing pain and potentially leading to life-threatening complications. While there's no cure for Crohn's disease, therapies can greatly reduce symptoms and even bring about long-term remission.

⚠️ Seek Immediate Medical Care

Call 911 or seek emergency care for: severe abdominal pain, high fever (>101°F), persistent vomiting, signs of intestinal blockage (severe cramping, inability to pass gas/stool), severe dehydration, or blood loss causing dizziness. These may indicate serious complications like perforation, abscess, or toxic megacolon.

Medical Disclaimer: This information is for educational purposes only and should not replace professional medical advice. Always consult with a qualified healthcare provider for diagnosis and treatment of any medical condition.

Understanding Crohn's Disease

Crohn's disease is one of two main forms of inflammatory bowel disease (IBD), the other being ulcerative colitis. Unlike ulcerative colitis, which only affects the colon and rectum, Crohn's can affect any part of the GI tract and involves all layers of the intestinal wall.

Key Characteristics

  • Skip lesions: Areas of inflammation alternate with healthy tissue
  • Transmural inflammation: Affects all layers of bowel wall
  • Can affect entire GI tract: Mouth to anus
  • Most common locations:
    • Terminal ileum (last part of small intestine)
    • Colon
    • Both ileum and colon (ileocolonic)

Disease Patterns

  • Inflammatory:
    • Superficial inflammation
    • Responds well to medical therapy
  • Stricturing (Fibrostenotic):
    • Narrowing of intestine
    • Can cause blockages
    • May require surgery
  • Penetrating (Fistulizing):
    • Creates abnormal connections
    • Abscesses and fistulas
    • Often requires surgery

Epidemiology

  • Affects about 500,000 Americans
  • Incidence: 3-20 per 100,000 annually
  • Peak onset: 15-35 years (second peak 60-80)
  • Equal gender distribution
  • Higher in developed countries
  • More common in urban areas

Causes and Risk Factors

The exact cause is unknown, but involves:

  • Genetics:
    • 15-20% have affected family member
    • Over 200 genes identified
    • NOD2/CARD15 most significant
  • Immune dysfunction:
    • Abnormal response to gut bacteria
    • Overactive immune response
  • Environmental factors:
    • Smoking (doubles risk)
    • NSAIDs
    • Diet (Western diet)
    • Stress (triggers flares)
    • Antibiotics in childhood

Signs and Symptoms

Symptoms vary depending on location and severity of inflammation. The disease typically follows a pattern of flares and remissions.

Common GI Symptoms

  • Diarrhea (90%):
    • Often chronic
    • May be bloody
    • Urgency common
    • Nocturnal diarrhea
  • Abdominal pain (70%):
    • Usually in lower right quadrant
    • Cramping nature
    • Often after meals
    • May indicate obstruction
  • Weight loss:
    • From poor absorption
    • Reduced food intake
    • Increased metabolic demands
  • Other GI symptoms:
    • Bloating and gas
    • Nausea and vomiting
    • Loss of appetite
    • Feeling of incomplete evacuation

Systemic Symptoms

  • Fatigue: Often severe and limiting
  • Fever: Low-grade, indicates inflammation
  • Anemia: From blood loss or poor absorption
  • Growth delay: In children and adolescents
  • Delayed puberty: From malnutrition

Extraintestinal Manifestations (25-40%)

Musculoskeletal:

  • Arthritis (most common)
  • Arthralgia
  • Ankylosing spondylitis
  • Osteoporosis

Skin:

  • Erythema nodosum (tender red nodules)
  • Pyoderma gangrenosum (ulcerating lesions)
  • Aphthous ulcers (mouth sores)
  • Psoriasis

Eyes:

  • Episcleritis
  • Uveitis
  • Conjunctivitis

Hepatobiliary:

  • Primary sclerosing cholangitis
  • Fatty liver disease
  • Gallstones

Perianal Disease (30%)

  • Fissures
  • Fistulas
  • Abscesses
  • Skin tags
  • May be first manifestation

Disease Course

  • Relapsing-remitting: Most common pattern
  • Chronic continuous: Persistent symptoms
  • Symptoms may precede diagnosis by years
  • Severity ranges from mild to severe

Diagnosis

No single test diagnoses Crohn's disease. Diagnosis requires combination of clinical, laboratory, endoscopic, and imaging findings.

Laboratory Tests

Blood Tests:

  • Inflammatory markers:
    • CRP elevated in 70-80%
    • ESR often elevated
    • May be normal in mild disease
  • Complete blood count:
    • Anemia common
    • Leukocytosis in active disease
    • Thrombocytosis
  • Nutritional markers:
    • Low albumin
    • Vitamin B12 deficiency
    • Iron deficiency
    • Vitamin D deficiency

Stool Tests:

  • Calprotectin/Lactoferrin:
    • Indicates intestinal inflammation
    • Helps differentiate from IBS
    • Monitors disease activity
  • Infectious workup:
    • Rule out C. difficile
    • Stool culture
    • Parasites

Endoscopy

Colonoscopy with Ileoscopy:

  • Gold standard for diagnosis
  • Allows tissue biopsy
  • Typical findings:
    • Skip lesions
    • Cobblestone appearance
    • Deep ulcers
    • Strictures
    • Fistulas

Upper Endoscopy:

  • If upper GI symptoms
  • 10-15% have upper tract involvement

Capsule Endoscopy:

  • Evaluates small bowel
  • When colonoscopy normal but suspicion high
  • Contraindicated if stricture suspected

Imaging Studies

CT/MR Enterography:

  • Evaluates small bowel
  • Detects complications
  • Shows:
    • Bowel wall thickening
    • Enhancement patterns
    • Strictures
    • Fistulas
    • Abscesses

Small Bowel Follow-Through:

  • Less used now
  • Shows strictures, fistulas

Ultrasound:

  • Non-invasive
  • Good for monitoring
  • Operator dependent

Histopathology

  • Non-caseating granulomas (30%)
  • Transmural inflammation
  • Focal chronic inflammation
  • Cryptitis and crypt abscesses

Treatment

Treatment aims to induce and maintain remission, prevent complications, and improve quality of life. Approach depends on location, severity, and complications.

Medical Management

5-Aminosalicylates (5-ASA):

  • Mild disease, especially colonic
  • Mesalamine, sulfasalazine
  • Limited efficacy in Crohn's
  • May help maintain remission

Corticosteroids:

  • For acute flares:
    • Prednisone 40-60mg daily
    • Budesonide for mild-moderate
    • Not for maintenance
  • Side effects limit long-term use

Immunomodulators:

  • Thiopurines:
    • Azathioprine, 6-mercaptopurine
    • Maintenance therapy
    • Takes 3-6 months to work
    • Monitor blood counts
  • Methotrexate:
    • Alternative to thiopurines
    • Intramuscular or subcutaneous
    • Contraindicated in pregnancy

Biologic Therapies:

  • Anti-TNF agents:
    • Infliximab (IV infusion)
    • Adalimumab (subcutaneous)
    • Certolizumab pegol
    • Effective for fistulas
  • Anti-integrin:
    • Vedolizumab
    • Gut-selective
    • Fewer systemic effects
  • Anti-IL-12/23:
    • Ustekinumab
    • For anti-TNF failures
  • Anti-IL-23:
    • Risankizumab
    • Newest class

Small Molecule Drugs:

  • JAK inhibitors:
    • Upadacitinib
    • Oral medication
    • Rapid onset

Nutritional Therapy

  • Exclusive enteral nutrition:
    • Effective in children
    • Induces remission
    • Liquid diet for 6-8 weeks
  • Partial enteral nutrition:
    • Supplemental nutrition
    • Maintains remission
  • Specific diets:
    • Low FODMAP
    • Specific Carbohydrate Diet
    • Mediterranean diet

Surgical Treatment

70-80% require surgery within 20 years. Indications include:

  • Failed medical therapy
  • Intestinal obstruction
  • Perforation
  • Abscess/fistula
  • Bleeding
  • Cancer/dysplasia

Surgical Options:

  • Resection: Remove diseased segment
  • Strictureplasty: Widen narrowed areas
  • Fistula repair
  • Abscess drainage
  • Proctocolectomy: For severe colonic disease

Living with Crohn's Disease

Diet and Nutrition

  • During remission:
    • Balanced, varied diet
    • High fiber if tolerated
    • Adequate protein
    • Stay hydrated
  • During flares:
    • Low-residue diet
    • Avoid trigger foods
    • Small, frequent meals
    • May need liquid diet
  • Common trigger foods:
    • High-fiber foods
    • Dairy (if lactose intolerant)
    • Fatty foods
    • Spicy foods
    • Alcohol
    • Caffeine

Lifestyle Modifications

  • Smoking cessation: Critical - smoking worsens disease
  • Stress management:
    • Can trigger flares
    • Meditation, yoga
    • Counseling
  • Exercise:
    • Regular, moderate activity
    • Improves well-being
    • May reduce inflammation
  • Sleep hygiene: Adequate rest important

Monitoring

  • Regular gastroenterologist visits
  • Lab monitoring based on medications
  • Colonoscopy surveillance
  • Bone density scans
  • Skin cancer screening (if on immunosuppressants)
  • Vaccinations up to date

Managing Flares

  • Recognize early signs
  • Contact healthcare team promptly
  • May need medication adjustment
  • Rest and stress reduction
  • Dietary modifications
  • Stay hydrated

Complications

Intestinal Complications

  • Strictures:
    • Narrowing from scar tissue
    • Can cause obstruction
    • May need surgery
  • Fistulas:
    • Abnormal connections
    • Between intestines or to skin
    • Perianal most common
  • Abscesses:
    • Pockets of infection
    • Need drainage
    • May require surgery
  • Perforation:
    • Medical emergency
    • Requires surgery
  • Toxic megacolon: Rare but serious

Malabsorption Issues

  • Vitamin B12 deficiency (terminal ileum)
  • Fat-soluble vitamin deficiency
  • Bile salt malabsorption
  • Short bowel syndrome (after surgery)
  • Osteoporosis

Cancer Risk

  • Small bowel adenocarcinoma
  • Colorectal cancer (with colonic involvement)
  • Lymphoma (rare)
  • Risk increases with duration and extent

Other Complications

  • Kidney stones
  • Gallstones
  • Primary sclerosing cholangitis
  • Venous thromboembolism
  • Growth failure in children

Prognosis

Disease Course

  • Highly variable between individuals
  • Most have periods of remission
  • 10-20% have prolonged remission after initial flare
  • 10-20% have continuously active disease
  • Disease behavior may change over time

Long-term Outlook

  • Life expectancy near normal with treatment
  • Quality of life can be excellent
  • Most people work and have families
  • 70-80% need surgery eventually
  • 30-50% need repeat surgery within 10 years

Factors Affecting Prognosis

  • Favorable:
    • Older age at diagnosis
    • Limited disease extent
    • Inflammatory phenotype
    • Good response to therapy
    • Non-smoker
  • Less favorable:
    • Young age at diagnosis
    • Extensive small bowel disease
    • Perianal disease
    • Stricturing/penetrating disease
    • Smoking
    • Need for steroids at diagnosis

With modern treatments including biologics and improved surgical techniques, most people with Crohn's disease can achieve good disease control and maintain an excellent quality of life. Early diagnosis, appropriate treatment, and regular monitoring are key to preventing complications and achieving the best outcomes.