Inflammatory Bowel Disease
A chronic autoimmune condition that causes severe inflammation and sores in the digestive tract, leading to diarrhea, pain, and weight loss.
Emergency Management: Toxic Megacolon. Stop antidiarrheals, NPO, IV fluids, IV steroids, broad-spectrum antibiotics, and stat surgical consult for potential colectomy.
Inflammatory Bowel Disease (IBD) encompasses two primary chronic, idiopathic, relapsing inflammatory disorders of the gastrointestinal tract: Ulcerative Colitis (UC), which is restricted to the colonic mucosa, and Crohn's Disease (CD), which can cause transmural inflammation anywhere from the mouth to the anus.
Detailed Overview
IBD results from an inappropriate and sustained mucosal immune response to normal intestinal flora in genetically susceptible individuals. UC presents with bloody diarrhea and superficial ulceration starting from the rectum and extending proximally. CD presents with abdominal pain, non-bloody diarrhea, and complications like strictures and fistulas due to transmural inflammation. Both carry significant risks of extraintestinal manifestations and long-term risk of colorectal cancer.
Epidemiology & Demographics
Highest incidence in North America and Northern Europe. Peaks in the 20s and 30s. Bimodal distribution with a second, smaller peak in the 50s-60s.
Etiological Mechanism
Complex interplay of genetic susceptibility (e.g., NOD2 gene in CD), environmental triggers (smoking, NSAIDs), gut microbiome dysbiosis, and an overactive mucosal immune system.
Primary Causes
Idiopathic immune dysregulation
In CD: Th1 and Th17 cell-mediated response causing transmural granulomatous inflammation. This thickens the bowel wall, leading to strictures (bowel obstruction), deep ulcers, and fistulas (connections between bowel loops or other organs). In UC: Th2 cell-mediated response causing superficial mucosal inflammation. Neutrophils infiltrate the crypts, causing crypt abscesses and friable, bleeding mucosa. Chronic inflammation leads to loss of haustra (lead-pipe appearance) and dysplasia.
Diagnostic Criteria & Guidelines
Combination of clinical history, endoscopic findings (colonoscopy/EGD), and histological confirmation via biopsy. Stool tests must rule out infection.
Mild UC: Topical (rectal) and oral 5-Aminosalicylates (e.g., Mesalamine 4.8g/day). Mild CD: Budesonide 9 mg PO daily for ileocecal disease. Moderate/Severe IBD: Systemic corticosteroids (Prednisone 40 mg daily) to induce remission, transitioning rapidly to biologic agents for maintenance.
Second-Line & Adjunctive Therapy
Biologics/Small molecules: Anti-TNF agents (Infliximab 5 mg/kg IV at weeks 0, 2, 6 then q8 weeks, or Adalimumab). Anti-integrins (Vedolizumab) or Anti-IL-12/23 (Ustekinumab).
Surgical & Procedural Management
UC: Total proctocolectomy with ileal pouch-anal anastomosis (IPAA) is curative for intestinal disease. CD: Bowel resection is not curative (disease recurs at anastomosis) but is required for strictures, abscesses, or fistulas.
Patient Counseling & Advice
Explain that IBD is a chronic disease requiring lifelong medication. Discuss that feeling well does not mean the inflammation is gone; mucosal healing is the target. Counsel on the importance of CRC screening 8 years after onset of pancolitis.
Follow-Up & Monitoring Schedule
Fecal calprotectin and CRP every 3-6 months. Surveillance colonoscopy every 1-2 years starting 8 years after disease onset for dysplasia screening.
Preventive Strategies
No primary prevention.
Chronic, relapsing-remitting course. Normal life expectancy, but significant morbidity. ~50% of CD patients require surgery within 10 years of diagnosis.