The site of bleeding duodenal ulcer is inside the ulcer, there may be bleeding in the center of the ulcer and there may be bleeding in the periphery of the ulcer. Duodenal ulcers are ulcerative lesions in the duodenum, usually in the bulb of the duodenum, either in the anterior wall of the bulb or in the posterior wall of the bulb. When the ulcer is deeper and invades the blood vessels, causing them to break down, the ulcer may bleed, but the amount of bleeding may be small, such as about 50 mL, and the patient will usually have black stools. Of course, if the bleeding volume is high and the bleeding rate is very fast, the patient may have abdominal distension and vomit blood, which may be coffee-colored blood at first, and dark red blood or bright red blood if the bleeding continues, etc. In most cases, the bleeding can be stopped by conservative medical treatment, but of course, if conservative medical treatment and endoscopic treatment are ineffective, emergency surgery is needed if necessary.