Peptic Ulcer Disease and Gastrointestinal Bleeding

The named artery depends on the named wall

Name the wall and you name the danger. The structure just beyond it is waiting.

A gastric ulcer on the lesser curvature can erode left gastric branches and cause upper gastrointestinal hemorrhage.

A posterior duodenal-bulb ulcer can enter the gastroduodenal artery and bleed briskly.

An anterior duodenal ulcer opens into the peritoneal cavity instead, because no large named artery guards its free surface.

In the duodenal bulb, posterior means artery and anterior means free perforation.

Gastric versus duodenal ulcer

Meal timing is the least reliable difference. Site, cancer concern, and mucosal physiology decide it.

Gastric ulcers favor the lesser curvature or antrum after H pylori or NSAIDs weaken mucosal defense. Biopsy at endoscopy generally excludes malignancy.

Duodenal ulcers sit in the bulb and track with H pylori, excess acid delivery, or impaired bicarbonate defense. Primary duodenal malignancy is far less likely.

The classic timing pattern exists. Gastric-ulcer pain may worsen with food, while duodenal-ulcer pain may briefly improve before returning hours later or at night. The overlap is why timing alone cannot decide.

Primary diagnostic image

Meal timing can support an ulcer location, but it cannot establish one.

Blood changes appearance with time and volume

Time darkens blood, transit preserves its color. The stool tells you how long the blood traveled.

Slow or moderate upper gastrointestinal bleeding turns black and tarry as melena after acid, enzymes, and intestinal transit work on it.

Very rapid upper bleeding can rush out as red hematochezia. Small chronic losses from any level may show up only as iron-deficiency anemia or positive stool testing.

Hematochezia with shock can still come from a brisk upper gastrointestinal hemorrhage.

The ligament of Treitz divides upper from lower bleeding

Stool color is a speed read, not a location read. Transit always comes first.

Proximal to the ligament of Treitz, the source is the esophagus, stomach, or duodenum. Hematemesis, coffee-ground emesis, or melena is the common result.

Distal to the ligament, the source is usually colon or anorectum, and hematochezia is the rule. The small bowel sits between the two territories.

The overlap is the trap here. A brisk upper source can outrun digestion into hematochezia, while slow right-colonic or small-bowel loss produces dark stool and iron-deficiency anemia.

H pylori and NSAIDs reach the same ulcer by different routes

H pylori changes the acid signals, NSAIDs strip the defense. Both end at the same ulcer.

H pylori drives chronic gastritis and disrupts somatostatin-gastrin signaling. It weakens bicarbonate defense, and depending on its distribution it can raise duodenal acid exposure or cause atrophic gastric injury.

NSAIDs inhibit cyclooxygenase-dependent prostaglandin synthesis. Mucosal blood flow, mucus, bicarbonate, epithelial repair, and platelet function all drop.

Once acid and pepsin win, a break through the muscularis mucosae is a true peptic ulcer. From that depth it can bleed, penetrate, perforate, or scar.

Hemorrhage, obstruction, perforation, and penetration

An ulcer changes character the moment it reaches a vessel, narrows the outlet, or leaves the wall.

Hemorrhage is the most common major complication. It runs from occult iron loss to shock with hematemesis, melena, or hematochezia.

Edema, spasm, or scarring near the pylorus or proximal duodenum can block the gastric outlet. Early satiety, retained food, a succussion splash, and nonbilious vomiting follow.

The trap here is mixing perforation with penetration. Perforation spills gas and contents into the peritoneum with free air. Penetration enters an adjacent organ such as the pancreas, and free intraperitoneal air may not appear.