Over the past 6 months, a 60-year-old woman with long standing duodenal ulcer disease has been complaining of anorexia, nausea, weight loss and repeated vomiting. She recognizes undigested food in the vomitus. Examination and workup reveal dehydration, hypokalemia, and hypochloremic alkalosis. What is the most likely diagnosis?

Chronic duodenal ulcer, with recurrent episode of healing and repair, may lead to pyloric obstruction due to scarring and stenosis of the duodenum. Painless vomiting of undigested food may occur once or twice a day. Surgical intervention should be carried out after correction of fluid and electrolyte imbalances. Preoperative antibiotics should be used due to bacterial overgrowth secondary to gastric static.