Patients receiving long-term hemodialysis develop GI telangiectasias involving the stomach, small intestine, and colon (642). (Telangiectasia refers to the dilation of preexisting vessels, whereas angiomatosis refers to the formation of new vessel growth.) The telangiectatic areas appear small, flattened, and reddish with fernlike margins. The lesions can be detected endoscopically or angiographically. Several factors predispose to the development of the telangiectasias. Chronic sodium and water overload may cause venous hypertension, thereby dilating submucosal veins. Additionally, dialysis patients receive long-term therapy with aluminum hydroxide gel to control hyperphosphatemia. This compound causes constipation, bowel distention, and cutaneous telangiectasias (642). Hemodialysis
patients also develop accelerated atherosclerosis, which may predispose the GI vasculature to develop abnormalities in a manner analogous to the angiodysplasia of the elderly (see Chapter 13).