Absence of ischemia in telangiectasias of chronic radiation proctopathy

Background and Study Aims: It has been postulated that chronic radiation proctopathy, clinically manifested by hematochezia and by the appearance of multiple telangiectasias, is caused by ischemia. This theory is based on reports that appeared in the 1980s which described obliterative endarteritis in patients with chronic radiation-induced ulcers. However, bleeding from radiation proctopathy is typically successfully treated endoscopically by widespread tissue coagulation, and the complications that would be expected to occur if the tissue was ischemic, such as poor wound healing, generally do not arise. We therefore hypothesized that the ischemia theory is incorrect and that rectal capillary oxygen saturation is normal in patients with telangiectasias of chronic radiation proctopathy. Patients and Methods: We developed a visible-light spectroscopy device that measures mucosal capillary hemoglobin oxygen saturation during endoscopy (having reported its operating characteristics previously). We prospectively studied 20 patients who had typical findings of multiple rectal telangiectasias, 1-20 years after undergoing external-beam irradiation for prostate or rectal carcinoma. We measured and compared the mucosal capillary oxygen saturations in the affected areas of the distal rectum and in endoscopically normal areas in the rectosigmoid colon. Results: Mucosal oxygenation was normal in all 20 patients in affected areas (64%-80%) and in unaffected areas (63%-75%). The mean mucosal hemoglobin oxygen saturation was actually slightly higher in the affected areas of the rectum than in the uninvolved rectosigmoid colon (73% vs. 69%, P < 0.01). Conclusions: The common form of chronic radiation proctopathy, characterized by multiple telangiectasias without ulcers or strictures, is not associated with ongoing mucosal ischemia. This finding may explain why endoscopic treatment of this disorder, in which large areas of the mucosa are coagulated with argon plasma or other treatment modalities that cause widespread ulceration, does not typically result in complications from poor wound healing.