---

GIT Pathology — Study Preparation Guide

---

⭐ PEPTIC ULCER DISEASE (PUD) — Priority Topic

Definition & Pathophysiology

• H. pylori infection (~70% of duodenal ulcers, ~50% of gastric ulcers)
• NSAIDs / aspirin (COX-1 inhibition → ↓ prostaglandins)
• Hypersecretory states (Zollinger-Ellison syndrome)
• Stress ulcers (Curling's — burns; Cushing's — CNS)

---

H. pylori Eradication Regimens

✅ FIRST-LINE: Standard Triple Therapy (7–14 days)

If penicillin allergy: replace amoxicillin with metronidazole 500 mg BID (PPI + Clarithromycin + Metronidazole)

• Duration: 14 days preferred over 7 days for higher eradication rates
• Eradication rate: ~70–85% (declining due to clarithromycin resistance)

---

✅ FIRST-LINE PREFERRED (ACG 2024): Bismuth Quadruple Therapy (BQT) — 14 days

"For treatment-naive patients with H. pylori infection, bismuth quadruple therapy (BQT) for 14 days is the preferred regimen when antibiotic susceptibility is unknown."

• Duration: 14 days
• Eradication rate: ~90%
• Advantage: Not affected by clarithromycin resistance
• Also packaged as Pylera (bismuth + metronidazole + tetracycline) + PPI

---

Triple vs. Quadruple — Key Comparison

---

When & How to Replace / Substitute Antibiotics

• Replace amoxicillin → Metronidazole 500 mg BID
• OR use BQT (no amoxicillin needed)

• Switch to BQT (bismuth quadruple)
• OR: Levofloxacin-based triple: PPI + Levofloxacin 500 mg OD + Amoxicillin 1000 mg BID × 14 days

• In triple therapy: replace metronidazole → amoxicillin (if not already used)
• Use BQT with higher metronidazole dose (500 mg QID instead of 250 mg) — partial resistance overcome by dose

• If first-line was triple → use BQT × 14 days
• If first-line was BQT → use Rifabutin-based triple: PPI + Rifabutin 150 mg BID + Amoxicillin 1000 mg BID × 14 days
• ACG: "In patients previously treated with optimized BQT, rifabutin triple therapy for 14 days is a suitable empiric alternative"

• Culture and susceptibility testing if available
• Levofloxacin triple (if not previously used)
• Furazolidone-based regimens (in some regions)

---

Summary: Eradication Therapy Algorithm

Treatment-naive patient
       ↓
Clarithromycin resistance unknown?
       ↓
→ BQT × 14 days  ← ACG 2024 PREFERRED
→ OR Triple therapy × 14 days (low resistance areas)

Treatment FAILURE:
First-line was Triple → Switch to BQT × 14 days
First-line was BQT   → Switch to Rifabutin Triple × 14 days

---

Confirming Eradication

• Test ≥4 weeks after completing therapy and ≥2 weeks off PPI
• Preferred: Urea Breath Test (UBT) or Stool Antigen Test
• Endoscopic biopsy + urease test if repeat endoscopy is indicated

---

Non-H. pylori Ulcers (NSAID-induced)

1. Stop the NSAID if possible
2. PPI (omeprazole 20–40 mg OD) × 4–8 weeks
3. If NSAID must continue: use selective COX-2 inhibitor + PPI
4. Misoprostol (prostaglandin analog) — alternative mucosal protection

---

DYSPLASIA (GIT Context)

Types

• Low-grade dysplasia (LGD): mild nuclear atypia, preserved architecture
• High-grade dysplasia (HGD): severe atypia, architectural disarray → precancerous

Key Contexts

Management of Dysplasia in IBD

• LGD (flat): chromoendoscopy surveillance; consider colectomy discussion
• HGD or multifocal LGD: colectomy recommended
• Raised/polypoid dysplasia: endoscopic resection if feasible
• Surveillance colonoscopy: every 1–2 years after 8–10 years of pancolitis

---

ULCERATIVE COLITIS (UC)

Key Features

• Continuous mucosal inflammation, rectum always involved, extends proximally
• Bloody diarrhea, tenesmus, urgency
• Limited to colon (unlike Crohn's)

Classification by Extent (Montreal)

Management by Severity

• 5-ASA (mesalazine/sulfasalazine) — first-line for induction and maintenance
  • Rectal foam/suppository for proctitis; oral for extensive disease
• Oral corticosteroids (prednisolone 40 mg/day) if 5-ASA fails

• IV corticosteroids (hydrocortisone 100 mg IV QID or methylprednisolone 60 mg/day)
• IV cyclosporine or infliximab as rescue therapy in steroid-refractory disease

• 5-ASA long-term (also reduces colorectal cancer risk)
• Thiopurines (azathioprine, 6-mercaptopurine) for steroid-dependent/recurrent disease
• Biologics: Infliximab, adalimumab (anti-TNF); vedolizumab (anti-integrin); ustekinumab

• Toxic megacolon, perforation, uncontrolled bleeding
• Medically refractory disease
• Dysplasia / carcinoma
• Surgery = curative (total colectomy + ileal pouch-anal anastomosis — IPAA / "J-pouch")

---

CROHN'S DISEASE

Key Features

• Transmural inflammation, skip lesions, any part of GIT (mouth to anus)
• Most common: terminal ileum + colon
• Cobblestone mucosa, fistulas, strictures, granulomas, non-caseating
• Non-bloody diarrhea, RIF pain, weight loss, perianal disease

Crohn's vs. UC — Comparison

Management

• Mild ileal/right colonic: Budesonide 9 mg/day × 8–12 weeks
• Moderate-severe: Systemic corticosteroids (prednisolone 40 mg/day)
• Severe/perianal: Biologics — infliximab, adalimumab (anti-TNF)

• Thiopurines (azathioprine 2–2.5 mg/kg/day)
• Methotrexate (15–25 mg/week IM/SC)
• Anti-TNF (infliximab, adalimumab) ± immunomodulator (combination)
• Vedolizumab (gut-selective anti-integrin)
• Ustekinumab (anti-IL12/23)

• Stricturoplasty for fibrous strictures
• Resection for localized refractory disease or complications (obstruction, fistula)

---

Quick Recall Summary Table

---

Study tip for tomorrow: Focus especially on the antibiotic substitution logic in H. pylori treatment — know what replaces what and why (resistance, allergy, prior failure). The distinction between triple and quadruple (bismuth) therapy, and when to escalate to rifabutin, is high-yield. For IBD, master the Crohn's vs. UC comparison table and the step-up treatment ladder.

---

🏥 GIT Diseases — Full Study Guide

---

⭐ PEPTIC ULCER DISEASE (PUD) — Main Focus

Pathophysiology in One Line

Causes

---

💊 H. pylori Eradication — The Heart of the Topic

REGIMEN 1 — Classic Triple Therapy (10–14 days)

• Eradication rate: ~70–85%
• Use where clarithromycin resistance is <15%
• Duration: 14 days preferred over 7 days

If penicillin allergy → replace amoxicillin with Metronidazole 500 mg BID Becomes: PPI + Clarithromycin + Metronidazole

---

REGIMEN 2 — Bismuth Quadruple Therapy / BQT (14 days) ⭐ ACG 2024 PREFERRED

"For treatment-naive patients with H. pylori infection, bismuth quadruple therapy (BQT) for 14 days is the preferred regimen when antibiotic susceptibility is unknown."

• Eradication rate: ~90%
• Not affected by clarithromycin resistance
• Also available as Pylera capsule (bismuth + metronidazole + tetracycline) + separate PPI

---

Triple vs. Quadruple — Side by Side

---

🔄 How We Replace / Change Antibiotics — High-Yield

Scenario 1 — Penicillin allergy (amoxicillin replacement)

• Triple becomes: PPI + Clarithromycin + Metronidazole
• OR switch entirely to BQT (no amoxicillin needed)

Scenario 2 — Clarithromycin resistance or prior macrolide use

• Switch to BQT × 14 days
• OR Levofloxacin triple: PPI + Levofloxacin 500 mg OD + Amoxicillin 1000 mg BID × 14 days

Scenario 3 — Metronidazole resistance

• In triple therapy: increase metronidazole dose (resistance is partially overcome by higher doses in BQT)
• Use tetracycline instead if available

Scenario 4 — First treatment FAILED (second-line)

Scenario 5 — Third-line / salvage

• Send culture + susceptibility testing → targeted therapy
• Levofloxacin triple (if not previously used)
• Furazolidone-based (resource-limited settings)

---

Eradication Decision Algorithm

Treatment-naive H. pylori
         ↓
Susceptibility unknown?
         ↓
 ┌───────────────────────────────────┐
 │  BQT × 14 days  ← PREFERRED      │
 │  OR Triple × 14d (low resistance) │
 └───────────────────────────────────┘
         ↓ Treatment FAILS
         ↓
First-line = Triple?  →  Give BQT × 14 days
First-line = BQT?     →  Rifabutin triple × 14 days
         ↓ Still fails
         ↓
Culture + sensitivity → targeted salvage

---

Confirming Eradication

• Test ≥4 weeks after completing antibiotics AND ≥2 weeks after stopping PPI
• Urea Breath Test (UBT) — preferred non-invasive
• Stool Antigen Test — alternative
• Endoscopic biopsy + rapid urease test — if endoscopy indicated anyway

---

Non-H. pylori Ulcers (NSAID-induced)

1. Stop NSAID if possible
2. PPI (omeprazole 20–40 mg OD) × 4–8 weeks for healing
3. If NSAID cannot be stopped: use selective COX-2 inhibitor + PPI
4. Misoprostol (prostaglandin analog) — mucosal protection alternative

---

DYSPLASIA IN THE GIT

What It Is

Key Clinical Settings

Management of Dysplasia in IBD

• LGD (flat): Enhanced surveillance with chromoendoscopy (dye spray + targeted biopsies); discuss colectomy
• HGD or multifocal LGD: Colectomy recommended
• Polypoid/raised dysplasia: Endoscopic resection if technically feasible
• Surveillance schedule: Colonoscopy every 1–2 years after 8–10 years of pancolitis

---

ULCERATIVE COLITIS (UC)

Hallmarks

• Continuous mucosal inflammation starting from rectum, extending proximally
• Bloody diarrhea, tenesmus, urgency, mucus
• Colon only — never involves small bowel (except backwash ileitis)

Extent Classification (Montreal)

Treatment Step-Up

1. 5-ASA (Mesalazine / Sulfasalazine) — first-line for induction AND maintenance
   • Suppositories/foam for proctitis; oral ± topical for extensive disease
2. Oral corticosteroids (Prednisolone 40 mg/day) if 5-ASA fails → taper over 8 weeks

• IV Cyclosporine (2 mg/kg/day)
• IV Infliximab (5 mg/kg)

• Thiopurines: Azathioprine 2–2.5 mg/kg/day or 6-Mercaptopurine
• Biologics: Infliximab, Adalimumab (anti-TNF); Vedolizumab (anti-integrin); Ustekinumab (anti-IL12/23)

• Indications: toxic megacolon, perforation, massive hemorrhage, medically refractory, dysplasia/cancer
• CURATIVE: Total proctocolectomy + ileal pouch-anal anastomosis (IPAA / J-pouch)

---

CROHN'S DISEASE

Hallmarks

• Transmural inflammation, skip lesions, any part of GIT (mouth to anus)
• Most common site: terminal ileum + proximal colon
• Non-caseating granulomas, cobblestone mucosa, fistulas, strictures, perianal disease
• Non-bloody diarrhea, RIF pain, weight loss, malabsorption

Crohn's vs. UC — Master Comparison

Treatment Step-Up

• Budesonide 9 mg/day × 8–12 weeks (topically acting steroid, low systemic side effects)

• Systemic corticosteroids: Prednisolone 40 mg/day → taper
• Metronidazole / Ciprofloxacin (for perianal/colonic disease)

• Anti-TNF biologics: Infliximab 5 mg/kg IV (0, 2, 6 weeks → every 8 weeks) or Adalimumab SC
• Combination therapy: Anti-TNF + Azathioprine (reduces immunogenicity, higher remission rates)

• Thiopurines: Azathioprine 2–2.5 mg/kg/day
• Methotrexate: 15–25 mg/week IM/SC (if thiopurine intolerant)
• Vedolizumab (gut-selective anti-integrin)
• Ustekinumab (anti-IL12/23)

• Stricturoplasty for fibrous strictures (preserves bowel length)
• Segmental resection for localized refractory disease
• Drainage of abscesses, repair of fistulas

---

Quick Master Summary Table

---

Exam focus for tomorrow: The most likely questions will center on (1) what drugs are in each H. pylori regimen, (2) what you do when a drug must be replaced (allergy, resistance, failure), and (3) the difference between Crohn's and UC. Know the algorithm from triple → BQT → rifabutin triple cold, and you will be well prepared.