Duodenal ulcer with arterial rupture. Close-up of a peptic ulcer in the duodenum of the small intestine, which has led to a ruptured artery. Peptic ulcers result from the caustic (burning) effects of acid and pepsin in the lining of the stomach or intestines. If the ulcer becomes too severe it can perforate the lining and leak into the abdominal cavity. However, if the ulcer erodes one of the blood vessels (as shown here) then the resultant severe bleeding can be life-threatening.