Bleeding can occur within the gastrointestinal tract from lesions such as gastric ulcers, duodenal ulcers, gastric varices, oesophageal varices, colonic diverticula or colonic ulcers. Modern endoscopic techniques can be used to stop bleeding from these lesions (endoscopic haemostasis). This includes the use of injection of adrenaline, thermocoagulation, haemoclipping and band ligation in conjunction with either oesophago-gastro-duodenoscopy (OGD) or colonoscopy.

Gastric and duodenal ulcers are seen in the illustrations on the left. In the bottom 2 illustrations, haemoclips have been applied to the bleeding vessels within the ulcer.