What are the typical presentation, differential diagnosis (ddx), investigations (invx), management (mx), and complications of Crohn's disease?

Crohn's Disease: Presentation, Diagnosis, Management, and Complications

Crohn's disease is a chronic inflammatory condition characterized by transmural inflammation that can affect any part of the gastrointestinal tract from mouth to perianal area, with the terminal ileum and colon being the most commonly affected sites. 1

Typical Presentation (Signs and Symptoms)

Common Clinical Features

• Abdominal pain (often in right lower quadrant)
• Chronic diarrhea (may be bloody)
• Weight loss
• Fatigue
• Fever
• Abdominal masses
• Perianal disease (fistulas, abscesses)

Distribution Patterns

• Ileitis only (25%)
• Colitis only (25%)
• Ileocolitis (50%) 2

Key Characteristics

• Discontinuous/skip lesions (affected areas interspersed with normal mucosa)
• Transmural inflammation (affecting all layers of the bowel wall)
• Asymmetric involvement
• Rectal sparing (in contrast to ulcerative colitis) 1

Differential Diagnosis (DDx)

Infectious Causes

• Bacterial infections (Salmonella, Shigella, Campylobacter, Yersinia)
• Tuberculosis
• Clostridium difficile colitis
• Cytomegalovirus enterocolitis 1, 3

Inflammatory Conditions

• Ulcerative colitis
• Microscopic colitis
• Behçet's disease
• Diverticular colitis
• Ischemic colitis
• Radiation enteritis 4, 3

Drug-Induced Conditions

• NSAID-induced enteropathy (must be withdrawn at least 4 weeks prior to diagnostic testing) 1, 4
• Other medication-induced colitis

Other Conditions

• Lymphoma
• Vasculitis
• Celiac disease 4, 3

Investigations (Invx)

Initial Laboratory Assessment

• Complete blood count (may show anemia, leukocytosis)
• C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR)
• Liver and renal function tests
• Iron studies
• Vitamin D level
• Vitamin B12 and folate levels
• Fecal calprotectin (high sensitivity for intestinal inflammation)
  • <50 mg/g: high sensitivity (88%) for ruling out inflammation

  • 250 mg/g: higher specificity (74%) for active inflammation 4, 5

Endoscopic Evaluation

• Ileocolonoscopy with biopsies is the gold standard for diagnosis 1
• Biopsy protocol:
  • At least two biopsies from terminal ileum
  • At least four biopsies from different colonic segments
  • Biopsies from rectum
  • Clearly identify sites of origin 1, 4

Histopathological Features

• Architectural distortion
• Crypt atrophy
• Increased lamina propria chronic inflammatory cells
• Paneth cell metaplasia
• Non-cryptolytic granulomas (strongly favor Crohn's over UC)
• Discontinuous distribution between and within sites 1

Imaging Studies

• MR enterography: preferred method for suspected small bowel involvement
• CT enterography: alternative if MRI unavailable
• Small bowel capsule endoscopy: high diagnostic yield for small bowel lesions, especially early mucosal lesions
• Abdominal ultrasound: useful for detecting complications 1, 4

Management (Mx)

Treatment Goals

• Improve or resolve symptoms
• Achieve and maintain deep remission
• Promote mucosal healing
• Prevent complications and disease progression
• Improve quality of life 1, 6

Induction of Remission

Mild to Moderate Disease

• Mesalamine products (for mild to moderate colonic disease)
• Antibiotics (metronidazole, fluoroquinolones)
• Budesonide (for ileal or right-sided colonic disease) 5

Moderate to Severe Disease

• Conventional glucocorticosteroids (prednisolone, methylprednisolone, IV hydrocortisone) for first presentation or single inflammatory exacerbation in a 12-month period 1
• Immunomodulators (azathioprine, 6-mercaptopurine, methotrexate)
• Biologic agents:
  • TNF inhibitors (infliximab, adalimumab, certolizumab)
  • Anti-integrin agents (vedolizumab)
  • Anti-IL-12/23 agents (ustekinumab) 1, 7, 2

Maintenance Therapy

• 5-aminosalicylic acid products
• Immunomodulators
• Biologic agents 2

Monitoring Disease Activity

• Clinical assessment
• Fecal calprotectin (every 3-6 months)
• Endoscopic evaluation for mucosal healing
• Cross-sectional imaging as needed for complications 1, 4

Surgical Management

• Required in up to two-thirds of patients during their lifetime
• Indications:
  • Medically refractory disease
  • Perforation
  • Persistent/recurrent obstruction
  • Abscess not amenable to percutaneous drainage
  • Intractable hemorrhage
  • Dysplasia or cancer 2
• Procedures:
  • Bowel resection
  • Stricturoplasty
  • Drainage of abscess

Complications

Intestinal Complications

• Strictures and obstruction
• Fistulas (enterocutaneous, enterovesical, enterovaginal, enteroenteric)
• Abscesses
• Perforation
• Massive hemorrhage
• Toxic megacolon
• Colorectal cancer 6, 2

Extraintestinal Manifestations

• Arthropathies (peripheral and axial)
• Ocular (episcleritis, uveitis, scleritis)
• Dermatologic (erythema nodosum, pyoderma gangrenosum)
• Hepatobiliary (primary sclerosing cholangitis, cholelithiasis)
• Metabolic bone disease (osteoporosis)
• Nephrolithiasis 5

Post-Surgical Complications

• Endoscopic recurrence at neoterminal ileum in 30-90% of patients within 12 months
• Almost universal recurrence by 5 years 2

Special Considerations

Upper GI Involvement

• Occurs in 0.5-16% of patients
• Often mild and nonspecific symptoms
• Predicts more severe disease phenotype
• Requires acid suppression therapy for symptomatic relief 8

Monitoring for Medication Side Effects

• Regular monitoring for potential adverse effects of immunosuppressive and biologic therapies
• Screening for infections (tuberculosis, hepatitis B) before initiating biologics 7

Crohn's disease management requires a comprehensive approach with close monitoring and adjustment of therapy based on disease activity. Early aggressive treatment in high-risk patients may help prevent complications and disease progression.