<prompt> Duodenal ulcer is most commonly caused by:March 2013 c, d, eGERDNSAID therapyStress ulcerH. pylori  <response>: Ans. D i.e. H. pyloriPeptic ulcerPeptic ulcer diseaseIt is defined as mucosal erosions equal to or greater than 0.5 cm.As many as 70-90 of such ulcers are associated with Helicobacter pylori, a helical-shaped bacterium that lives in the acidic environment of the stomach.Four times as many peptic ulcers arise in the duodenum--the first pa of the small intestine, just after the stomach--as in the stomach itself.About 4 of gastric ulcers are caused by a malignant tumor, so multiple biopsies are needed to exclude cancer.Duodenal ulcers are generally benign. 