A 38-year-old woman on chronic ibuprofen therapy for rheumatoid arthritis presents with epigastric pain and dyspepsia for 3 months. Upper endoscopy shows a 1.5 cm antral ulcer with clean base. H. pylori serology is negative. Which investigation is most appropriate to confirm the diagnosis and assess ulcer healing?

## Investigation for NSAID-Induced Ulcer Confirmation and Healing Assessment ### Clinical Scenario This patient has an endoscopically-proven ulcer in the setting of chronic NSAID use (ibuprofen) with negative H. pylori serology. The diagnosis of NSAID-induced peptic ulcer is clinically clear, but confirmation of healing and exclusion of malignancy require follow-up endoscopy. ### Why Repeat Endoscopy with Biopsy? **Key Point:** In patients with gastric ulcers (especially antral location), repeat endoscopy with biopsies of the ulcer margin is mandatory to exclude gastric malignancy, even if the initial appearance is benign. **High-Yield:** Gastric ulcers carry a small but real risk of malignancy (~1–3%), particularly in patients >40 years. Biopsies from the ulcer edge (not the base) are required to rule out dysplasia or carcinoma. Duodenal ulcers do not require follow-up endoscopy unless complicated. **Clinical Pearl:** Follow-up endoscopy should be performed 4–6 weeks after starting PPI therapy and NSAID cessation. Complete healing confirms benign ulcer; failure to heal or suspicious features warrant further investigation (EUS, CT). ### Diagnostic Algorithm: Gastric vs Duodenal Ulcer ```mermaid flowchart TD A[Peptic ulcer on endoscopy]:::outcome --> B{Location?}:::decision B -->|Duodenal| C[Treat with PPI + stop NSAID]:::action B -->|Gastric| D[Biopsy ulcer margin now]:::action C --> E[No follow-up endoscopy needed]:::outcome D --> F[Benign histology]:::outcome D --> G[Dysplasia/cancer]:::urgent F --> H[Repeat endoscopy in 4-6 weeks]:::action H --> I[Healed?]:::decision I -->|Yes| J[Confirm benign, stop PPI]:::outcome I -->|No| K[EUS or CT for malignancy]:::action ``` ### Why Not the Other Options? | Investigation | Use | Why Not Here | |---|---|---| | **Faecal calprotectin** | Inflammatory bowel disease (Crohn's, UC) | Patient has NSAID-induced ulcer, not IBD; not indicated | | **Serum pepsinogen I/II ratio** | Research/screening for atrophic gastritis | Not standard for diagnosis or monitoring of peptic ulcer healing | | **Abdominal CT with contrast** | Complications (perforation, obstruction) or staging | Patient is stable; CT not needed unless malignancy suspected on biopsy | **Mnemonic:** **GRAB** — Gastric ulcer requires Repeat endoscopy, Biopsies, Assessment of healing, Benign confirmation. [cite:Harrison 21e Ch 297]