Inflammatory Bowel Disease

IBD Overview - Fiery Bowel Blues

• Chronic, relapsing idiopathic inflammation of GIT.
• Two main types: Ulcerative Colitis (UC) & Crohn's Disease (CD).
• Epidemiology:
  • Peak incidence: 15-30 years & 50-80 years (bimodal).
  • Slight female predominance.
  • Higher in developed nations.
• Risk factors:
  • Genetics (e.g., NOD2/CARD15 for CD).
  • Smoking (Worsens CD, Protects UC 📌).
  • Diet (Western diet), NSAIDs.
  • Altered gut microbiota.

⭐ Extraintestinal manifestations (EIMs) are common, occurring in up to 50% of IBD patients; arthritis is the most frequent EIM_._

Crohn's vs UC - The Great Divide

⭐ Extraintestinal manifestations (EIMs) are common in IBD. Primary Sclerosing Cholangitis (PSC), a significant EIM, has a strong association with Ulcerative Colitis (approx. 70% of PSC patients have UC).

📌 Mnemonic:

• CD: "GRANny skips on COBBLESTONES from GUM to BUM, but SMOKING makes her FISTulae WORSE."
• UC: "ULCERS in the COLON are CONTINUOUS from the RECTUM, SMOKING is PROTECTIVE, but watch for CANCER."

Clinical & Diagnosis - Spotting the Signs

• Common Symptoms:
  • Ulcerative Colitis (UC): Bloody diarrhea (hallmark), tenesmus, urgency, LLQ abdominal pain. Systemic symptoms less prominent.
  • Crohn's Disease (CD): Abdominal pain (RLQ, colicky), weight loss, fatigue, diarrhea (often non-bloody). Perianal disease common.
• Key Extraintestinal Manifestations (EIMs): (~25-40% IBD patients) 📌 A PIE SAC
  • Arthritis (peripheral/axial), Aphthous stomatitis
  • Pyoderma gangrenosum
  • Iritis/Uveitis
  • Erythema nodosum
  • Sclerosing cholangitis (PSC - UC, ↑cancer risk)
  • Clubbing, Cholelithiasis (CD - ileal)
• Diagnostic Approach:
  • Labs: CBC (anemia), ↑ESR/CRP, fecal calprotectin. p-ANCA (UC ~60%), ASCA (CD ~60%).
  • Endoscopy + Biopsy (Definitive):
    • UC: Continuous inflammation (rectum proximally), friability, pseudopolyps. Biopsy: cryptitis, crypt abscesses.
    • CD: Skip lesions, aphthous/linear ulcers, cobblestoning, transmural. Biopsy: non-caseating granulomas (pathognomonic, ~30-50%).
  • Imaging (CT/MR Enterography): Small bowel, transmural extent, complications (strictures, fistulae, abscesses).

⭐ While crypt abscesses are characteristic of UC, they can also be seen in severe CD; non-caseating granulomas are specific to CD but only found in ~30-50% of biopsies.

Management - Taming the Flames

• Medical Therapy (Step-Up):
  • Mild: 5-ASA (Mesalamine, Sulfasalazine) for UC; Budesonide for ileocolonic CD.
  • Moderate Flares: Systemic Corticosteroids (Prednisolone $~1mg/kg$, max 40-60mg), taper on remission.
  • Maintenance/Steroid-Sparing: Immunomodulators (Azathioprine, 6-MP, MTX). Monitor side effects.
  • Severe/Refractory: Biologics (📌AIVU: Adalimumab, Infliximab, Vedolizumab, Ustekinumab).

    ⭐ Infliximab requires latent TB screening (reactivation risk).

• Surgical Therapy:
  • Ulcerative Colitis (UC):
    • Indications: Refractory, dysplasia/cancer, toxic megacolon ($>6cm$ dilation + toxicity), perforation, hemorrhage.
    • Procedure: Total Proctocolectomy with IPAA (curative).
  • Crohn's Disease (CD):
    • Indications: Complications (strictures, fistulas, abscesses, obstruction), refractory disease.
    • Procedures: Conservative resection, stricturoplasty. Not curative.

High‑Yield Points - ⚡ Biggest Takeaways

• Crohn's Disease: Characterized by transmural inflammation, skip lesions, fistulas, and strictures; smoking is a significant risk factor.
• Ulcerative Colitis: Features continuous mucosal inflammation typically starting in the rectum, with risk of toxic megacolon; smoking is paradoxically protective.
• Extraintestinal manifestations like arthritis, uveitis, and skin lesions are common in both.
• Surgical indications for Crohn's: Primarily for complications (e.g., stricture, fistula, abscess); bowel conservation (e.g., strictureplasty) is paramount.
• Surgical indications for UC: Includes medically refractory disease, dysplasia/cancer, or acute severe colitis; total proctocolectomy with IPAA is curative.
• Both IBD types carry an increased colorectal cancer risk, necessitating regular surveillance.
• Key serological markers: p-ANCA often positive in UC, ASCA often positive in Crohn's Disease.