Angiodysplasia: characterization, diagnosis, and advances in treatment. Gastrointestinal bleeding accounts for 2% of all adult hospital admissions each year. Angiodysplasia is one of the most frequently reported causes of lower gastrointestinal bleeding. In 80% of patients with bleeding angiodysplasia, the bleeding will stop spontaneously, but will often recur. Although angiography may detect bleeding in 86% of actively bleeding patients, the bleeding rate must be at least 0.5 mL/min. The treatment of choice for control of bleeding has been resection of the suspected segment of bowel, but this procedure is associated with a 10% rebleeding rate and 7% to 8% mortality. Superselective catheterization with infusion of vasoconstrictors has been used to control bleeding, but effects are short-lived. Superselective embolization occludes an offending vessel, but is difficult to perform accurately and is associated with risk of infarction. Laser photocoagulation controls bleeding in 84% of patients, with a 6% complication rate. This method of controlling bleeding offers distinct advantages, especially for the hemodynamically unstable patient. Except for cases in which surgical resection is indicated, Nd:YAG laser photocoagulation is the safest, least invasive, and probably most effective means of treating angiodysplasia. 