A gastrointestinal arteriovenous malformation is a rare defect of tangled veins and arteries involving the intestine. This defect can occur anywhere in the intestine. The defect creates an abnormal collection of blood vessels that can put pressure on other parts of your body that are close by. It causes blood vessels to expand (dilate) over time and sometimes bleed. Many people with this defect never have any symptoms. This defect is present at birth (congenital).
What are the causes?
This defect is present at birth (congenital). Why this defect develops is not known.
What are the signs or symptoms?
Signs and symptoms often do not appear until you are older and may include:
Blood in your stool.
Black or dark red stools.
Weakness.