RESUMEN
A duodenal diverticulum is most common in the medial aspect of the second portion of the duodenum and rarely causes symptoms. An obstruction, bleeding, perforation, jaundice and pancreatitis are uncommon complications of a duodenal diverticulum. Bleeding from the periampullary diverticulum should be considered in the diagnosis of a patient who presents with upper gastrointestinal bleeding of unknown origin. The second portion of the duodenum is sometimes difficult to observe entirely from the tangent line with the use of a forward-viewing endoscope. The diagnosis and treatment of periampullary diverticular bleeding may be achieved more easily by use of a side-viewing endoscope. We report here a case of narrow opened periampullary diverticular bleeding diagnosed by the use of a side-viewing endoscope with difficulty