(See also Overview of Gastrointestinal Bleeding.)
Vascular ectasias (angiodysplasias, arteriovenous malformations) are dilated, tortuous vessels that typically develop in the cecum and ascending colon. They occur mainly in people > 60 and are the most common cause of lower gastrointestinal (GI) bleeding in that age group. They are thought to be degenerative and do not occur in association with other vascular abnormalities. Most patients have 2 or 3 lesions, which are typically 0.5 to 1.0 cm, bright red, flat or slightly raised, and covered by very thin epithelium.
Vascular ectasias also occur in association with a number of systemic diseases (eg, renal failure, aortic stenosis, cirrhosis, CREST syndrome [calcinosis cutis, Raynaud phenomenon, esophageal dysmotility, sclerodactyly, telangiectasias]—see Pathophysiology) and after radiation to the bowel.
Gastric antral vascular ectasia (watermelon stomach or GAVE) consists of large dilated veins running linearly along the stomach, creating a striped appearance suggestive of a watermelon. The condition occurs mainly in older women and is of unknown etiology.
Hereditary hemorrhagic telangiectasia (Rendu-Osler-Weber syndrome) is an autosomal dominant disorder that causes multiple vascular lesions in various parts of the body, including the entire GI tract. GI bleeding rarely occurs before age 40.
Dieulafoy lesion is an abnormally large artery that penetrates the gut wall, occasionally eroding through the mucosa and causing massive bleeding. It occurs mainly in the proximal stomach.
Arteriovenous malformations and hemangiomas, both congenital disorders of blood vessels, can occur in the GI tract but are rare.
Vascular lesions are most commonly diagnosed endoscopically. If routine endoscopy is nondiagnostic, small-bowel endoscopy, capsule endoscopy, intraoperative endoscopy, or visceral angiography may be required. Technetium-99m–labeled red blood cell scans are less specific but may help localize the lesion enough to facilitate endoscopy or angiography.
Endoscopic coagulation (with heater probe, laser, argon plasma, or bipolar electrocoagulation) is effective for many vascular lesions. Vascular ectasias are treated with endoscopic coagulation if they are thought to be the cause of bleeding. Endoscopic clips may be applied to some lesions. They often recur, although there is some evidence that oral estrogen-progesterone combinations may limit recurrence.
Mild recurrent bleeding can be treated simply with chronic iron therapy. More significant bleeding that is unresponsive to endoscopic measures may require angiographic embolization or surgical resection. However, rebleeding occurs in about 15 to 25% of surgically treated patients.