Condition Basics

What is diverticular bleeding?

Diverticular bleeding occurs when pouches (diverticula) that have developed in the wall of the large intestine (colon) bleed. If you have these pouches, you have a condition called diverticulosis. Diverticular bleeding causes a large amount of blood to appear in your stool.

What causes it?

The reason pouches (diverticula) form in the colon wall is not completely understood. Doctors think diverticula form when high pressure inside the colon pushes against weak spots in the colon wall.

Normally, a diet with enough fiber (also called roughage) produces stool that is bulky and can move easily through the colon. If a diet is low in fiber, the colon must exert more pressure than usual to move small, hard stool. A low-fiber diet also can increase the time stool remains in the bowel, adding to the high pressure.

Pouches may form when the high pressure pushes against weak spots in the colon. Weak spots are where blood vessels pass through the muscle layer of the bowel wall to supply blood to the inner wall.

Bleeding occurs when the blood vessel going to the pouch breaks open.

What are the symptoms?

Diverticular bleeding usually causes sudden, severe bleeding from the rectum. The blood may be dark red or bright red, and there may be clots. In most cases there is no abdominal (belly) pain.

How is it diagnosed?

Diverticular bleeding is diagnosed by ruling out other causes of the bleeding. Your doctor will do a medical history and physical exam, along with some tests. Colonoscopy—the inspection of the entire large intestine (colon) using a long, flexible, lighted viewing scope (colonoscope)—is thought to be one of the most useful tests for finding the source of bleeding in the lower intestines. An imaging test such as CT angiography may be done to find the location of persistent bleeding.

How is diverticular bleeding treated?

Bleeding from diverticula often will stop on its own. If it doesn't, treatment may be needed to stop it and to replace lost blood, and you may need to be hospitalized. Treatment may include intravenous fluids, blood transfusions, and injection of medicines.

How can you prevent it?

Eating a high-fiber diet, getting plenty of fluid, and exercising regularly may help prevent the formation of diverticula. But if you already have diverticulosis, diet may not help prevent bleeding.

You may have a higher risk of diverticular bleeding if you take aspirin or blood thinners. Talk to your doctor about the benefits and risks of these medicines.