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 fibre (also called roughage) produces stool that is bulky and can move easily through the colon. If a diet is low in fibre, the colon must exert more pressure than usual to move small, hard stool. A low-fibre 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 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. Imaging tests such as angiography (also known as arteriography) may be done to find the location of persistent bleeding. 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.

Your doctor might do a test called a technetium-labelled red blood cell bleeding scan to look for the source of bleeding. In this test, some blood is taken from you, and a small amount of radioactive material called technetium is added to the blood. The blood containing the technetium is then injected back into your bloodstream and traced to the source of 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, injection of medicines, and in some cases surgery to remove the diseased part of the colon.

How can you prevent it?

Eating a high-fibre 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 regularly (more than 4 days a week).^{footnote 1}