Proctoscopy is a common medical procedure in which an instrument called a proctoscope (also known as a rectoscope, although the latter may be a bit longer) is used to examine the anal cavity, rectum, or sigmoid colon. A proctoscope is a short, straight, rigid, hollow metal tube, and usually has a small light bulb mounted at the end. It is approximately 5 inches or 15 cm long, while a rectoscope is approximately 10 inches or 25 cm long. 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 hemorrhoids or rectal polyps and might be mildly uncomfortable as the proctoscope is inserted further into the rectum. Modern fibre-optic proctoscopes allow more extensive observation with less discomfort.