Stomach ulcers can cause symptoms such as burning or gnawing pain in the upper abdomen, bloating and nausea. If left untreated, ulcers can lead to complications like bleeding or perforation. Diagnosis often involves endoscopy, where a flexible tube with a camera is inserted into the stomach to visualise and potentially treat the ulcer. Additionally, blood tests and stool tests may be conducted to check for the presence of the bacterium Helicobacter pylori, a common cause of ulcers.