350.1 🎓 醫孞生版

350.1.0.1 📌 䞀頁重點

350.1.0.1.1 IBS Definition + Diagnosis

350.1.1 Rome IV Criteria

  • Recurrent abdominal pain ≥ 1 day/week × 3 months
  • 2+ of:
    • Related to defecation
    • Change in stool frequency
    • Change in stool form (appearance)
  • Symptoms onset ≥ 6 months
  • Exclude alarms

350.1.2 Bristol Stool Scale

  • 1: separate hard lumps
  • 2: lumpy sausage
  • 3: cracked sausage
  • 4: smooth sausage (normal)
  • 5: soft blobs with clear-cut edges
  • 6: fluffy, mushy
  • 7: liquid

350.1.3 Subtypes

  • IBS-D: > 25% loose, < 25% hard (diarrhea predominant)
  • IBS-C: > 25% hard, < 25% loose (constipation predominant)
  • IBS-M: mixed (both ≥ 25%)
  • IBS-U: unspecified

350.1.4 Alarm Features (Warrant Further Workup)

  • ≥ 50 yo new onset
  • Weight loss
  • Hematochezia
  • Anemia
  • Family history GI cancer
  • Nocturnal symptoms
  • Persistent severe symptoms
350.1.4.0.1 Epidemiology
  • 10-15% prevalence (US, Europe, Asia)
  • F > M (2:1)
  • Onset typically < 50 yo
  • ↑ Comorbidities: anxiety, depression, somatic disorders, fibromyalgia
350.1.4.0.2 Pathophysiology

Multifactorial: - Visceral hypersensitivity - Altered GI motility - Altered microbiome (dysbiosis) - Low-grade inflammation - Brain-gut axis dysfunction - Psychosocial stress - Post-infectious IBS (gastroenteritis can trigger) - Genetic predisposition

350.1.4.0.3 Diagnosis

350.1.5 Clinical

  • Detailed history (Rome IV)
  • Physical exam (often normal)
  • Triggers + alleviating factors
  • Psychosocial assessment

350.1.6 Limited Workup (No Alarm Features)

  • CBC
  • BMP
  • Fecal calprotectin (rule out IBD)
  • Celiac serology (especially IBS-D)
  • TSH
  • C. diff if recent antibiotic / hospital
  • Stool studies for chronic if needed

350.1.7 Colonoscopy

  • Alarm features
  • ≥ 50 yo
  • IBS-D refractory (microscopic colitis)
  • Family history CRC

350.1.8 Imaging

  • Limited role unless specific concern
350.1.8.0.1 Treatment — General Approach

Education + Reassurance: - Patient-physician relationship critical - Validate symptoms - Set expectations - Treatment may take time

350.1.9 Dietary

Low FODMAP Diet (Most Evidence): - Fermentable Oligosaccharides, Disaccharides, Monosaccharides, And Polyols - Restriction → 4-6 weeks → reintroduction - 50-75% improve - Dietitian guidance helpful - Avoid: wheat, onions, garlic, lactose, certain fruits

Other Dietary: - Identify trigger foods - Lactose-free if intolerant - Gluten-free if celiac excluded (some IBS benefit) - Probiotics (mixed evidence) - Avoid excess caffeine, alcohol

350.1.10 Lifestyle

  • Stress management
  • Exercise
  • Sleep

350.1.11 Pharmacologic by Subtype

IBS-C Treatment: - Polyethylene glycol (PEG) — first-line laxative - Linaclotide (Linzess) — guanylate cyclase C agonist - Lubiprostone (Amitiza) — chloride channel activator - Plecanatide (Trulance) — GC-C agonist - Tenapanor (Ibsrela) — NHE3 inhibitor - Prucalopride (Motegrity) — 5-HT4 agonist

IBS-D Treatment: - Loperamide (Imodium) — mu-opioid receptor agonist; symptomatic - Rifaximin (Xifaxan) — non-absorbed antibiotic; 14-day course - Eluxadoline (Viberzi) — mu-opioid agonist + delta antagonist; avoid in hx pancreatitis/cholecystectomy - Alosetron (Lotronex) — 5-HT3 antagonist; REMS program; women only - Bile acid sequestrants (cholestyramine) if bile acid diarrhea - Probiotics (variable evidence)

Pain Management: - Antispasmodics: dicyclomine, hyoscyamine, peppermint oil - TCAs (low-dose amitriptyline 10-25 mg HS) — pain + diarrhea; IBS-D - SSRIs — pain; some IBS-C benefit - Pregabalin / gabapentin — visceral pain (off-label)

Psychological Therapies: - Cognitive Behavioral Therapy (CBT) — most evidence - Hypnotherapy (gut-directed) - Mindfulness approaches

350.1.12 Newer + Emerging

Microbiome Modulation: - Probiotics (specific strains) - FMT (fecal microbiota transplant) — trials for IBS

Microbiome-Targeted Therapies: - Various in development

Gut-Brain Axis Modulators: - New compounds investigating

350.1.12.0.1 Functional Constipation

350.1.13 Rome IV Criteria

  • ≥ 2 of:
    • < 3 BM/week
    • Straining > 25%
    • Lumpy or hard stools
    • Sensation of incomplete evacuation
    • Sensation of anorectal obstruction
    • Manual maneuvers
  • Loose stools rarely without laxatives
  • Insufficient criteria for IBS

350.1.14 Subtypes

  • Slow Transit Constipation (colonic inertia)
  • Outlet Dysfunction (pelvic floor dyssynergia)
  • Normal Transit Constipation

350.1.15 Workup

  • Anorectal manometry + balloon expulsion (outlet)
  • Colonic transit study (slow transit)
  • Defecography (structural)

350.1.16 Treatment

  • Lifestyle (fiber, fluid, exercise)
  • Osmotic laxatives (PEG)
  • Stimulant laxatives (senna, bisacodyl)
  • Prokinetics (prucalopride)
  • Lubiprostone, linaclotide for resistant
  • Biofeedback for outlet dysfunction
350.1.16.0.1 Cyclic Vomiting Syndrome (CVS)

350.1.17 Clinical

  • Recurrent stereotyped episodes of nausea + vomiting
  • Symptom-free intervals
  • Often associated with migraine
  • Triggers: stress, infection

350.1.18 Treatment

  • Acute: ondansetron, lorazepam, hydration
  • Preventive: amitriptyline, propranolol, topiramate
  • Avoid triggers
350.1.18.0.1 Cannabinoid Hyperemesis Syndrome (CHS)

350.1.19 Clinical

  • Heavy chronic cannabis use
  • Cyclic vomiting episodes
  • Relief from hot showers/baths (pathognomonic)
  • Long-term cannabis use

350.1.20 Treatment

  • Cannabis cessation (definitive)
  • Hot showers symptomatic
  • Antiemetics
  • Topical capsaicin
350.1.20.0.1 Globus Sensation

350.1.21 Definition

  • Lump in throat without dysphagia
  • Functional disorder

350.1.22 Workup

  • Rule out GERD, thyroid, mass
  • ENT exam

350.1.23 Treatment

  • Reassurance
  • PPI trial
  • Voice therapy
  • CBT
350.1.23.0.1 Functional Heartburn (Rome IV)

350.1.24 Definition

  • Heartburn without acid reflux or hypersensitivity

350.1.25 Treatment

  • TCAs / SSRIs
  • CBT
  • Hypnotherapy

350.1.25.1 🩺 床邊速查

  • IBS: Rome IV criteria + alarm exclusion
  • Subtypes: IBS-D, IBS-C, IBS-M, IBS-U
  • Workup: fecal calprotectin (rule out IBD); celiac serology (esp IBS-D)
  • Treatment foundation: low FODMAP diet + education
  • IBS-C: linaclotide, lubiprostone, plecanatide, tenapanor, prucalopride
  • IBS-D: rifaximin, eluxadoline, alosetron, loperamide
  • Both: TCA, SSRI, antispasmodics, peppermint oil
  • CBT: most evidence for psychological therapy
  • Microbiome modulation: emerging (FMT trials)