 In a peptic ulcer it is believed to be a result of edema and scarring of the ulcer, followed by healing and fibrosis, which leads to obstruction of the gastroduodenal junction (usually an ulcer in the first part of the duodenum).The most confirmatory investigation is endoscopy of upper gastrointestinal tract.Laboratory often find hypochloremic, hypokalemic, and alkalotic due to loss of hydrogen chloride and potassium.