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Gastric Ulcer vs Duodenal Ulcer — A Detailed Comparison

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1. Definition

"Duodenal ulcer was traditionally viewed as a disease of increased acid-peptic action on the duodenal mucosa, whereas gastric ulcer was viewed as a disease of weakened mucosal defenses." — Schwartz's Principles of Surgery, 11th ed.

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2. Epidemiology

"On average, gastric ulcer patients are older than duodenal ulcer patients, and the incidence is increasing in the elderly, perhaps because of increasing NSAID and aspirin use." — Schwartz's Principles of Surgery, 11th ed.

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3. Location

Gastric Ulcer

• Most commonly on the lesser curvature of the stomach, at the junction of the body and antrum (angularis incisura / incisura angularis)
• The Johnson classification of gastric ulcers by site:
  • Type I — Lesser curvature at the incisura (most common, ~60%); normal or ↓ acid
  • Type II — Body of stomach + concurrent duodenal ulcer; associated with ↑ acid
  • Type III — Prepyloric; associated with ↑ acid (behaves like duodenal ulcer)
  • Type IV — High on lesser curvature, near gastroesophageal junction; normal or ↓ acid
  • Type V — Anywhere in stomach; NSAID-induced

Duodenal Ulcer

• First part of the duodenum (duodenal bulb), within a few centimetres of the pyloric valve
• The anterior wall of the duodenal bulb is the most common site

"Peptic ulcers are most common in the gastric antrum and first portion of the duodenum." — Robbins & Kumar Basic Pathology, 11th ed.

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4. Pathophysiology

Gastric Ulcer

• H. pylori colonizes the antrum, releases CagA toxin and urease → breaks down the mucus-bicarbonate barrier and causes direct epithelial injury
• NSAIDs inhibit COX-1 → ↓ prostaglandin E₂ → ↓ mucus and bicarbonate secretion → ↓ mucosal blood flow
• Acid secretion is normal or reduced in Type I GU (parietal cell mass is not increased)
• Bile reflux from the duodenum contributes to mucosal damage in some patients
• Smoking ↓ mucosal blood flow and ↓ prostaglandin synthesis

Duodenal Ulcer

• H. pylori preferentially infects the antrum → antral gastritis → ↑ gastrin release → ↑ parietal cell stimulation → elevated BAO and MAO
• Parietal cell mass may be increased (~2× normal)
• H. pylori also suppresses somatostatin-secreting D cells → loss of inhibitory brake on gastrin
• Increased rate of gastric emptying → larger acid load per unit time reaches duodenum
• Decreased duodenal bicarbonate secretion (due to H. pylori) impairs neutralization
• Gastric metaplasia in the duodenum → H. pylori can colonize duodenum → local mucosal injury

"Gastric ulcers form primarily because the mucosal barrier is defective... In duodenal ulcers, patients produce more acid than normal controls in response to any known acid secretory stimulus." — Costanzo Physiology, 7th ed. / Schwartz's Surgery, 11th ed.

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5. Acid Secretion Profile

"Patients with type I gastric ulcer usually have normal or decreased acid secretion." — Schwartz's Principles of Surgery, 11th ed.

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6. Gross Morphology

• Solitary in >80% of patients
• Round to oval, sharply punched-out defect with clean, smooth base
• Mucosal margin is flush with surrounding mucosa (NOT heaped up — raised margins suggest carcinoma)
• Mucosal folds radiate from the ulcer crater ("radiating folds" on barium study)
• Scarring may involve full thickness, drawing surrounding mucosa inward

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7. Histology

1. Thin fibrinoid necrosis — on the luminal surface
2. Neutrophilic inflammatory infiltrate — active inflammation
3. Granulation tissue — immature vessels, mononuclear leukocytes
4. Collagenous/fibrous scar at the base — thickened, occasionally thrombosed vessels (source of life-threatening haemorrhage)

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8. Clinical Features

"Patients with duodenal ulcer often experience pain 2 to 3 hours after a meal and at night. Two-thirds of patients with duodenal ulcers will complain of pain that awakens them from sleep. The pain of gastric ulcer more commonly occurs with eating and is less likely to awaken the patient at night." — Schwartz's Principles of Surgery, 11th ed.

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9. Complications

"The significant difference is the possibility of malignancy in a gastric ulcer. This critical difference necessitates... biopsies." — Sabiston Textbook of Surgery, 21st ed.

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10. H. pylori and Aetiology

"More than 70% of PUD cases are associated with H. pylori infection." — Robbins & Kumar Basic Pathology, 11th ed.

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11. Diagnosis

• All gastric ulcers must be biopsied (multiple biopsies from margin and base) to exclude malignancy
• Duodenal ulcers do not require routine biopsy unless atypical
• Biopsy antrum/body for H. pylori (rapid urease test, histology)

• GU: niche/crater on lesser curvature, radiating folds, Hampton's line (thin lucent line across ulcer neck)
• DU: deformity of duodenal cap ("cloverleaf" deformity), spasm, constant filling defect

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12. Medical Treatment

1. PPI therapy (omeprazole, lansoprazole, pantoprazole) — mainstay; heals both GU and DU
   • DU: 4–6 weeks; GU: 8–12 weeks (needs endoscopic confirmation of healing)
2. H. pylori eradication — Triple or quadruple therapy; dramatically reduces recurrence
3. Discontinue NSAIDs/aspirin where possible; if continued, add PPI co-prescription
4. Lifestyle: stop smoking, avoid alcohol and ulcerogenic drugs

"Helicobacter treatment dramatically decreases the recurrence rate of both duodenal and gastric ulcer." — Schwartz's Principles of Surgery, 11th ed.

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13. Surgical Treatment

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14. Summary Comparison Table

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• Schwartz's Principles of Surgery, 11th Edition — Chapter 26
• Robbins & Cotran Pathologic Basis of Disease, 10th Edition — Chapter 17
• Robbins & Kumar Basic Pathology, 11th Edition — Chapter 13
• Costanzo Physiology, 7th Edition — Chapter 8
• Guyton and Hall Textbook of Medical Physiology — Chapter 67
• Sabiston Textbook of Surgery, 21st Edition — Chapter on Gastric and Duodenal Ulcers
• Sleisenger and Fordtran's Gastrointestinal and Liver Disease — Chapter 20/53

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Triple Therapy for H. pylori Eradication

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Background

"Failure of monotherapy and dual therapy for treatment of H. pylori infection prompted the development of triple therapy and other multidrug regimens." — Yamada's Textbook of Gastroenterology, 7th ed.

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Classic Triple Therapy — Components

The Three Standard Regimens

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PPI Options

• Raises intragastric pH → creates environment less hostile to antibiotics
• Increases half-life and stability of clarithromycin and amoxicillin in gastric mucus
• H. pylori is in a replicative state at higher pH → more susceptible to bactericidal antibiotics
• Has synergistic bactericidal effect

"Acid suppression with PPI has synergistic bactericidal effects and stabilizes antibiotics, so increasing their half-life... H. pylori is more likely in a nonreplicative state in low gastric pH but is more replicative and therefore susceptible to amoxicillin and clarithromycin when the pH rises." — Yamada's Gastroenterology, 7th ed.

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Duration

"Simpler (dual therapy) and shorter regimens (7 and 10 days) are not as effective as triple therapy for 14 days." — Harrison's Principles of Internal Medicine, 22nd ed.

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Mechanism of Each Drug

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Efficacy and the Resistance Problem

• Cure rates of <80% (and in some regions <50%) are now widely reported — in Greece, India, Italy, Japan, Mexico, and Spain
• Clarithromycin resistance rates of >15% are now common across most of Europe, Asia, and the Americas
• Metronidazole resistance is also significant but has less clinical impact (metronidazole resistance can be partially overcome by higher doses)

"Using triple therapy as first-line treatment, cure rates of less than 80% (and even below 50%) are now widely reported across countries." — Yamada's Textbook of Gastroenterology, 7th ed.

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Causes of Triple Therapy Failure

1. Clarithromycin resistance — most important cause
2. Poor patient adherence — high pill burden / side effects
3. Inadequate acid suppression (especially in CYP2C19 extensive metabolisers who rapidly metabolise PPIs)
4. Metronidazole resistance (when PAM used)
5. Reinfection (rare in developed countries)

"Failure of H. pylori eradication with triple therapy in a compliant patient is usually due to infection with a resistant organism. Additional important factors in treatment failure include inadequate acid suppression and inadequate adherence." — Harrison's Principles of Internal Medicine, 22nd ed.

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Alternative and Rescue Regimens

1. Bismuth Quadruple Therapy (now often first-line)

• Eradication rates ≥90% first-line; 79–88% as second-line
• Major drawback: 17–34 pills/day (Pylera combination capsule reduces this to 14/day)
• Metronidazole resistance has much less impact here than clarithromycin resistance does in triple therapy

2. Sequential Therapy

• Days 1–5: PPI + Amoxicillin
• Days 6–10: PPI + Clarithromycin + Tinidazole (or metronidazole)
• Eradication ~85–90% in original studies

3. Concomitant (Non-bismuth Quadruple) Therapy

• PPI + Amoxicillin + Clarithromycin + Nitroimidazole — all four drugs simultaneously × 10–14 days
• Overcomes clarithromycin resistance better than sequential therapy

4. Levofloxacin Triple Therapy (second-line)

• PPI + Amoxicillin + Levofloxacin 500 mg OD × 5–7 days
• Used when both clarithromycin and metronidazole resistance suspected

5. Rifabutin Triple Therapy (salvage/third-line)

• PPI + Amoxicillin + Rifabutin
• Reserved for multiply treatment-resistant cases; used in areas of high fluoroquinolone resistance

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Confirming Eradication

• ¹³C-urea breath test — preferred non-invasive test
• Stool antigen test — acceptable alternative
• Repeat endoscopy with biopsy — used when endoscopy is required anyway (e.g., gastric ulcer follow-up)

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Indications for H. pylori Eradication (and Thus Triple Therapy)

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Summary

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• Harrison's Principles of Internal Medicine, 22nd Edition — Chapter 335 (Table 335-4)
• Yamada's Textbook of Gastroenterology, 7th Edition — Chapter 49 (Table 49.5)
• Schwartz's Principles of Surgery, 11th Edition — Chapter 26
• Maastricht V/Florence Consensus Guidelines (Malfertheiner et al., Gut 2017/2022)