Peptic Ulcer Disease I: Introduction

Peptic ulcer disease, or PUD, involves true ulcers in the stomach or duodenum that extend through the muscularis mucosae into the submucosa or deeper layers.

These ulcers can cause serious complications such as bleeding or perforation.

Normally, the mucosal barrier includes bicarbonate-rich mucus, tight epithelial junctions, and adequate blood flow. These defenses protect the stomach lining from gastric acid and pepsin. When these defenses are disrupted, ulcers can form.

The bacterium Helicobacter pylori, a major cause of peptic ulcers, colonizes the stomach lining and releases urease, protease, phospholipase, and cytotoxins that damage the mucosal barrier and trigger inflammation.

NSAIDs like aspirin cause ulcers by inhibiting cyclooxygenase enzymes and reducing prostaglandins, which protect the stomach lining through mucus, bicarbonate secretion, and blood flow maintenance.

Additional risk factors include irritants like alcohol and tobacco, and in critically ill patients, stress-induced vasoconstriction due to reduced gut blood flow, also known as splanchnic hypoperfusion.