UWorld Internal Medicine Practice Test

The most common site for a peptic ulcer is the duodenum. Peptic ulcers generally arise due to an imbalance between aggressive factors, such as gastric acid and pepsin, and protective factors, including the mucosal barrier. The duodenum, being the first part of the small intestine just beyond the stomach, frequently encounters acidic gastric contents. It is particularly vulnerable to ulceration caused by factors such as Helicobacter pylori infection, prolonged use of non-steroidal anti-inflammatory drugs (NSAIDs), and excessive acid production.

Duodenal ulcers are more prevalent compared to those found in the stomach or esophagus. While stomach ulcers can occur, they are less common than duodenal ulcers. The esophagus and jejunum are also not typical sites for peptic ulcers. The esophagus may develop ulcers but these are usually related to reflux disease and present in a different pathological context. The jejunum is not a common site for ulceration due to peptic disease, as it normally has a more alkaline environment and the protective mucosal layer is more intact. Hence, the duodenum stands out as the predominant location for peptic ulcers.