A 48-year-old woman on chronic NSAID therapy presents with epigastric pain. A 35-year-old man with H. pylori infection presents with similar symptoms. Which feature best distinguishes NSAID-induced peptic ulcers from H. pylori-associated ulcers?

Explanation

## Anatomical Distinction: NSAID vs. H. pylori Peptic Ulcers ### Location as the Primary Discriminator **Key Point:** The anatomical site of ulceration is the most reliable and clinically useful feature that distinguishes NSAID-induced ulcers from H. pylori-associated ulcers. ### Comparison Table: NSAID vs. H. pylori Peptic Ulcers | Feature | NSAID-Induced Ulcer | H. pylori-Associated Ulcer | | --- | --- | --- | | **Primary location** | Anterior duodenal wall, lesser curve of stomach | Posterior duodenal wall, greater curve of stomach | | **Mechanism** | Direct mucosal injury + COX inhibition | Chronic inflammation + acid hypersecretion | | **Associated gastritis** | Minimal or absent | Chronic active gastritis with intestinal metaplasia | | **Acid secretion** | Normal or low | Often elevated (especially in duodenal ulcers) | | **Prevalence** | More common in gastric ulcers | More common in duodenal ulcers | | **Bleeding risk** | High (anterior wall erosion) | Moderate | | **Perforation risk** | High (anterior wall perforation) | Moderate | | **Recurrence after healing** | Low (if NSAID stopped) | High (if H. pylori not eradicated) | ### Anatomical Explanation **High-Yield:** - **NSAID ulcers** on the **anterior duodenal wall** and **lesser curve** occur because these are the most exposed areas to direct NSAID contact and gastric acid. - **H. pylori ulcers** on the **posterior duodenal wall** and **greater curve** occur because H. pylori colonizes the antrum and body, triggering acid-mediated ulceration in these regions. ### Clinical Implications **Clinical Pearl:** The anatomical location has critical surgical implications: - **Anterior duodenal ulcer perforation** → penetrates into the peritoneal cavity → acute peritonitis (classic presentation: sudden severe epigastric pain, board-like rigidity) - **Posterior duodenal ulcer erosion** → erodes into the gastroduodenal artery → massive GI bleeding (often without preceding perforation symptoms) ### Why Location Matters **Mnemonic: "APE" for NSAID ulcers** — **A**nterior wall, **P**erforation risk, **E**xposed to acid and drug. **Mnemonic: "PGA" for H. pylori ulcers** — **P**osterior wall, **G**reater curve, **A**cid hypersecretion. [cite:Robbins 10e Ch 17]