Peptic Ulcer Disease I: Introduction

Peptic ulcer disease involves true ulcers in the stomach or duodenum that extend through the muscularis mucosae into the submucosa or deeper layers. Unlike superficial erosions affecting only the mucosal layer, these deeper ulcers can cause serious complications such as bleeding or perforation when they damage blood vessels.

Helicobacter pylori colonizes the stomach lining and releases urease, protease, phospholipase, and cytotoxins that damage the mucosal barrier and trigger inflammation. The bacterium secretes urease to neutralize gastric acid, allowing it to survive while simultaneously injuring epithelial cells and degrading the protective mucus layer.

NSAIDs like aspirin inhibit cyclooxygenase enzymes and reduce prostaglandins, which normally protect the stomach lining through mucus secretion, bicarbonate production, and blood flow maintenance. By suppressing these protective mechanisms, NSAIDs significantly weaken the mucosal barrier and increase ulcer risk in susceptible patients.

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 protective mechanisms are disrupted by infection, medications, or reduced blood flow, ulcers can develop.

Acute ulcers are short-lived with minimal inflammation and heal quickly after the irritant is removed. Chronic ulcers persist, may recur, and often cause scarring due to ongoing tissue damage. Understanding this distinction helps predict healing timelines and treatment responses in clinical practice.

Beyond H. pylori and NSAIDs, risk factors include alcohol and tobacco irritation, corticosteroid use that suppresses prostaglandin synthesis, impaired blood flow from severe anemia, hyperacidity from excess gastrin, and lifestyle factors like irregular eating and excessive caffeine consumption that disrupt gastric homeostasis.

In critically ill patients, stress induces vasoconstriction that reduces gut blood flow, a condition called splanchnic hypoperfusion. This impaired blood flow compromises the mucosal barrier's ability to maintain protective bicarbonate secretion and healing, significantly increasing susceptibility to stress-induced ulcer formation.