Proctoscopy is a common medical procedure in which an instrument called a proctoscope (also known as a rectoscope) is used to examine the anal cavity, rectum or sigmoid colon. A proctoscope is a short (10in or 25cm long), straight, rigid, hollow metal tube, which usually has a small light bulb mounted at the end. During proctoscopy, the proctoscope is lubricated and inserted into the rectum, and then the obturator is removed, allowing an unobstructed view of the interior of the rectal cavity. This procedure is normally done to inspect for haemorrhoids or rectal polyps. Modern fibre-optic proctoscopes allow more extensive observation with less patient discomfort.

Disposable proctoscopes without lights are also available. The proctoscope also has a hollow channel through which other instruments may be inserted. For example, another instrument may be used to take a biopsy of a small amount of tissue for examination under a microscope. Similar instruments are the sigmoidoscope and colonoscope.