Angiodysplasia of the colon is enlarged and fragile blood vessels in the colon that result in occasional loss of blood from the gastrointestinal (GI) tract.

Angiodysplasia of the colon is mostly related to the aging and degeneration of the blood vessels. It usually occurs in older adults.

There are several theories about the cause. The most likely cause is that normal spasms of the colon lead to enlargement of blood vessels in the area. This swelling becomes so severe that a small direct passageway develops between a very small artery and vein. This is called an arteriovenous fistula. It is in this area of the colon wall that the patient is at risk for bleeding.

Angiodysplasia of the colon is very rarely related to other diseases of the blood vessels, including Osler-Weber-Rendu syndrome. It is not related to cancer, and is different than diverticulosis, another very common cause of intestinal bleeding in older adults.

The symptoms vary. Often, in elderly patients, the symptoms are weakness, fatigue, and shortness of breath due to anemia. There may not be any signs of bleeding directly from the colon. Others may have occasional mild or severe bleeding episodes with bright red blood coming from the rectum.

Some patients may have dark or black, tarry stools. There is no pain associated with angiodysplasia.

Tests that may be done to diagnose this condition include:

• Angiography (only useful if there is active bleeding into the colon)
• Complete blood count (CBC) to check for anemia
• Colonoscopy
• Stool guaiac test (a positive test result suggests bleeding from the colon)

When a person is bleeding from the colon, it is important to determine the source of the bleeding and how fast they are losing blood. The patient's condition must be evaluated continuously and may need to be admitted to a hospital's intensive care unit (ICU). Fluids may be given through a vein, and blood products may be required.

Treatment begins once the source of bleeding is found. Most patients stop bleeding on their own without any treatment.

If treatment is needed, it may involve:

• Angiography to help form a clot in the bleeding area or to deliver medicine to help cause the blood vessels to tighten to stop the bleeding
• Burning (cauterizing) the site of the bleed with heat or a laser using a colonoscope
• Using electrical energy (argon plasma coagulation) to stop bleeding

In some instances, surgery is the only option. Removal of the entire right side of the colon (right hemicolectomy) is the treatment of choice for someone with this condition who continues to bleed at a dangerously quick rate, despite several treatments by angiography and colonoscopy.

Patients who have bleeding related to this condition despite having had colonoscopy, angiography, or surgery are likely to have more bleeding in the future.

The goal of therapy is to reduce, if not totally eliminate, the number of bleeds, hospitalizations, and blood transfusions. Surgery may be a cure in some cases. The outlook remains good if the bleeding is controlled.

• Anemia
• Death from excessive blood loss
• Side effects from treatment
• Severe loss of blood from the GI tract

Call your health provider if rectal bleeding or black stools occur.

There is no known prevention.

Hauser S. Vascular diseases of the gastrointestinal tract. In: Goldman L, Ausiello D. Cecil Textbook of Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 146.