There are two main causes of black stools caused by cirrhosis: 1. Patients with cirrhosis are often combined with portal hypertension, and portal hypertensive gastropathy is a relatively common complication that can manifest itself as erosion and congestion of the gastric mucosa, or combined with gastric ulcers, duodenal bulb ulcers, etc. If the erosion or ulcer causes black stool and the ulcer is small, it is possible that the ulcer will heal on its own and the bleeding will stop, but the chances of this are relatively low. If the ulcer is larger and deeper, it is difficult to heal by itself, and the lack of timely medication will lead to continued black stools and even anemia and hypotension. 2, caused by portal hypertension, commonly bleeding from ruptured esophageal or gastric fundic varices. This kind of bleeding is more aggressive, the possibility of self-healing is almost non-existent. As a result, black stools will persist and there may even be a large vomiting of blood from the upper gastrointestinal tract. Regardless of the cause, it is important to seek prompt medical attention for any black stools combined with cirrhosis.