PROCTOSCOPE

lighted tube that is used by physicians for the visual inspection of the rectum and lower colon. The instrument consists of a 25-centimetre- (10-inch-) long metal or plastic tube with a strong, dependable light. Modern proctoscopes often use optic fibres to deliver light at the inserted end, whereas older instruments used an external light source located near the examiner's eye. The proctoscope allows the entire surface of the rectal lining to be examined for evidence of disease. It is passed into the anal canal using gentle pressure and is gradually advanced as far as is comfortable for the patient being examined. Proctoscopy or proctosigmoidoscopy (in which the lower or sigmoid colon is also observed) is a standard part of the physical examination of older persons. The rigid instrument has been somewhat replaced by flexible instruments using optic fibres to transmit both light from the outside and images of the intestine. These flexible instruments allow more extensive observation with less patient discomfort.