351.2 🩺 國考版

351.2.1 高頻考點

351.2.1.1 CD vs UC Hallmarks (MEMORIZE)

  • CD: transmural, skip lesions, any GI, fistulas, granulomas, smoking worse
  • UC: mucosal, continuous from rectum, colorectum, bloody diarrhea, no granulomas, smoking protective

351.2.1.2 Distribution

  • CD: ileocolic (50%), ileal only (30%), colonic only (20%), perianal common
  • UC: proctitis (rectum), left-sided, pancolitis

351.2.1.3 Extraintestinal Manifestations

  • Joints: peripheral arthritis (type 1 parallels disease, type 2 independent), AS
  • Skin: erythema nodosum (UC), pyoderma gangrenosum
  • Eye: uveitis, episcleritis
  • Liver: PSC strongly UC-associated
  • Renal: oxalate stones (CD)
  • Hematologic: anemia, hypercoagulability

351.2.1.4 Diagnosis

  • Colonoscopy + ileal intubation + biopsy (gold standard)
  • Fecal calprotectin
  • MRE for CD (small bowel)
  • pANCA (UC), ASCA (CD)

351.2.1.5 Treatment Modalities

5-ASA (Mesalamine): - UC mainstay (mild-moderate) - Less effective in CD

Corticosteroids: - Induction for moderate-severe - Not for maintenance

Immunomodulators: - Thiopurines (TPMT testing) - Methotrexate (CD)

Biologics:

Anti-TNF: infliximab, adalimumab, certolizumab, golimumab (UC) Anti-Integrin: vedolizumab (gut-selective) Anti-IL-12/23: ustekinumab Anti-IL-23: risankizumab (CD FDA 2022 + UC 2024), mirikizumab (UC FDA 2023), guselkumab JAK Inhibitors: tofacitinib (UC), upadacitinib (UC + CD) S1P Modulators: ozanimod (UC FDA 2021), etrasimod (UC FDA 2023)

351.2.1.6 Toxic Megacolon

  • Severe UC complication

  • 6 cm transverse colon

  • Systemic toxicity
  • IV steroids + abx + cyclosporine/infliximab rescue
  • Colectomy if refractory 24-72 hr

351.2.1.7 Pouchitis

  • After IPAA (J-pouch) in UC patients
  • Treatment: metronidazole, ciprofloxacin
  • Recurrent: biologics

351.2.1.8 CRC Surveillance

  • 8-10 years post-onset (UC)
  • Earlier with PSC
  • Colonoscopy q 1-2 yr
  • Random biopsies + chromoendoscopy

351.2.1.9 Pregnancy + IBD

  • Continue biologics (TNF inhibitors safe)
  • Methotrexate teratogenic — stop
  • Plan with specialist

351.2.1.10 Key Trials

  • SONIC: infliximab + AZA vs each in CD
  • GEMINI: vedolizumab UC + CD
  • UNITI/IM-UNITI: ustekinumab CD
  • U-EXCEL/U-EXCEED: upadacitinib CD
  • ADVANCE/MOTIVATE: risankizumab CD
  • LUCENT-1/LUCENT-2: mirikizumab UC
  • TRUE NORTH: ozanimod UC
  • OASIS / ELEVATE UC: etrasimod UC

351.2.2 易混淆比范

Drug Class Examples Use Notes
5-ASA Mesalamine, sulfasalazine UC mild-mod Topical for distal
Corticosteroids Prednisone, budesonide Induction Not maintenance
Thiopurines AZA, 6-MP Maintenance TPMT testing
Methotrexate — CD Bone, liver tox
Anti-TNF Infliximab, adalimumab Mod-severe TB screen
Vedolizumab Entyvio UC + CD Gut-selective
Ustekinumab Stelara UC + CD IL-12/23
Risankizumab Skyrizi CD + UC IL-23 selective
Mirikizumab Omvoh UC IL-23 selective
Tofacitinib Xeljanz UC JAK; CV risk
Upadacitinib Rinvoq UC + CD JAK
Ozanimod Zeposia UC S1P modulator
Etrasimod Velsipity UC S1P modulator

351.2.3 Special Topics

351.2.3.1 IBD-Unclassified

  • Cannot distinguish CD vs UC
  • 5-10% of IBD cases
  • Treat per dominant features

351.2.3.2 Microscopic Colitis

  • Different from IBD
  • Older patients
  • Chronic watery diarrhea
  • Normal endoscopy; diagnosis on biopsy
  • Treatment: budesonide

351.2.3.3 Indeterminate Colitis

  • Similar to IBD-unclassified
  • May reclassify over time