(also, rectoscopy), in medicine, a diagnostic method that consists in the examination of rectal mucosa with a proctoscope, a steel tube 25–30 cm in length and 1.5–2 cm in diameter equipped with an electric light on a long rod and an ocular.
Proctoscopy is performed with the patient in a knee-elbow position after the preliminary preparation, which consists in the administration of an enema. The proctoscope is inserted slowly and carefully into the anus under visual control. The rectum must be inflated with air in order to have its lumen clearly visible. Proctoscopy makes it possible to detect tumors, ulcers, and cicatricial stenoses, to remove a small amount of tissue for biopsy, to remove rectal polyps, and to perform the electrocoagulation of a polyp. During proctoscopy the mucosae of both the rectum and the distal portion of the sigmoid are examined; the latter procedure is called rectoromanoscopy. Flexible fibercolonoscopes are used in the examination of deeper sections of the large intestine, including the cecum; this procedure is called colonoscopy.