Bleeding from diverticulosis mainly causes a lot of blood to appear in the stool. This bleeding usually cause no abdominal pain and stops on its own, according to WebMD.
Diverticulosis causes severe bleeding from the rectum, causing bright red or dark red clots. Since this bleeding is mainly painless, most people do not realize they have this condition. This bleeding starts suddenly, requires no treatment and stops on its own, notes WebMD.
The cause of diverticulosis is unknown. Doctors believe that this condition occurs when pressure within the large intestine pushes against the colonic walls, forming diverticula, or bulging sacs. These sacs can occur throughout the large intestine, but they are common in curves between the colon and rectum, says MedicineNet.com.