Angiodysplasia: Acquired degenerative dilation or expansion (ectasia) of normal BLOOD VESSELS, often associated with aging. They are isolated, tortuous, thin-walled vessels and sources of bleeding. They occur most often in mucosal capillaries of the GASTROINTESTINAL TRACT leading to GASTROINTESTINAL HEMORRHAGE and ANEMIA.Gastrointestinal Hemorrhage: Bleeding in any segment of the GASTROINTESTINAL TRACT from ESOPHAGUS to RECTUM.Argon Plasma Coagulation: A method of tissue ablation and bleeding control that uses ARGON plasma (ionized argon gas) to deliver a current of thermocoagulating energy to the area of tissue to be coagulated.Gastric Antral Vascular Ectasia: A distinct vascular lesion in the PYLORIC ANTRUM that is characterized by tortuous dilated blood vessels (ectasia) radiating outward from the PYLORUS. The vessel pattern resembles the stripes on the surface of a watermelon. This lesion causes both acute and chronic GASTROINTESTINAL HEMORRHAGE.Colonic Diseases: Pathological processes in the COLON region of the large intestine (INTESTINE, LARGE).Capsule Endoscopy: Non-invasive, endoscopic imaging by use of VIDEO CAPSULE ENDOSCOPES to perform examination of the gastrointestinal tract, especially the small bowel.Upper Gastrointestinal Tract: The segment of GASTROINTESTINAL TRACT that includes the ESOPHAGUS; the STOMACH; and the DUODENUM.Hemostasis, Endoscopic: Control of bleeding performed through the channel of the endoscope. Techniques include use of lasers, heater probes, bipolar electrocoagulation, and local injection. Endoscopic hemostasis is commonly used to treat bleeding esophageal and gastrointestinal varices and ulcers.Telangiectasia, Hereditary Hemorrhagic: An autosomal dominant vascular anomaly characterized by telangiectases of the skin and mucous membranes and by recurrent gastrointestinal bleeding. This disorder is caused by mutations of a gene (on chromosome 9q3) which encodes endoglin, a membrane glycoprotein that binds TRANSFORMING GROWTH FACTOR BETA.Endoscopy, Gastrointestinal: Endoscopic examination, therapy or surgery of the gastrointestinal tract.Colonoscopy: Endoscopic examination, therapy or surgery of the luminal surface of the colon.Arteriovenous Malformations: Abnormal formation of blood vessels that shunt arterial blood directly into veins without passing through the CAPILLARIES. They usually are crooked, dilated, and with thick vessel walls. A common type is the congenital arteriovenous fistula. The lack of blood flow and oxygen in the capillaries can lead to tissue damage in the affected areas.