The goal of this clinical trial is to evaluate oxygenation in the colon in people with acquired vascular abnormalities in the proximal colon.

The etiology of acquired vascular abnormalities of the large bowel (i.e. angiodysplasia, AVM, hemangiomas of the cecum. etc.) are unknown. These lesions typical appear as ectatic, dilated, and tortuous blood vessels within the submucosa and mucosa of the GI tract. In some patients they are the cause of acute large volume bleeding or a slower chronic bleed that manifests as chronic iron deficiency anemia. These lesions are more common in older individuals and those with underlying cardiac, pulmonary, and renal disease. As such, it is hypothesized that these lesions may result from chronic hypoxia. This study aims to evaluate oxygenation of the colon in people with acquired vascular abnormalities in the proximal colon compared to healthy controls.

Inclusion Criteria:

• Undergo standard of care colonoscopy
• People with a history of vascular lesions of the colon
• People with healthy colon
• 18 - 89 years of age

Exclusion Criteria:

• Age < 18 years
• Age > 90 years
• People with ulcerations in at ascending colon opposite the ileocecal valve
• Previous colon surgery