Ulcer general lesion, usually shallow, on the skin or on the mucous membrane lining a body cavity, including inside the intestine which is, in fact, skin folded inside the body and vastly modified to perform specialised functions. To the common man the term 'ulcer', however, means ulcer in the gastrointestinal tract generally described as peptic ulcer.

Two types of peptic ulcer can be distinguished - those of the stomach are gastric ulcer and of part of the small intestine (duodenum), duodenal ulcer. Gastric ulcer is frequently associated with infection of the stomach lining by recently recognised bacteria called Helicobacter pylori. This organism is unusually resistant to very high acidity of the stomach and can thus establish infection readily inside the stomach. Correlation of gastric ulcer and occurrence of H. pylori in the stomach is very high in Bangladeshi population, as it is true in other parts of the world as well. Approximately 3 million peptic ulcer cases are estimated to be seen by hospitals each year. Incidence of H. pylori infection in the population is high. Approximately 70% adults are infected recently or show immunological evidence of infection in the past. Most subjects are adults above the age of 30. [Zia Uddin Ahmed]