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

Rectum

The rectum is the final straight portion of the large intestine in some mammals, and the gut in others, terminating in the anus. The human rectum is about 12 cm long...

 or sigmoid colon

Sigmoid colon

The sigmoid colon is the part of the large intestine that is closest to the rectum and anus. It forms a loop that averages about 40 cm...

. 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

Rectum

The rectum is the final straight portion of the large intestine in some mammals, and the gut in others, terminating in the anus. The human rectum is about 12 cm long...

, and then the obturator

Obturator

Obturator may refer to:In medicine:* Obturator artery* Obturator nerve* Obturator vein* Obturator externus muscle* Obturator internus muscle* Obturator membrane* Obturator canal* Obturator foramen...

 is removed, allowing an unobstructed view of the interior of the rectal cavity. This procedure is normally done to inspect for hemorrhoids or rectal polyp

Polyp

A polyp in zoology is one of two forms found in the phylum Cnidaria, the other being the medusa. Polyps are approximately cylindrical in shape and elongated at the axis of the body...

s 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.

Disposable proctoscopes without light 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

Biopsy

A biopsy is a medical test involving sampling of cells or tissues for examination. It is the medical removal of tissue from a living subject to determine the presence or extent of a disease. The tissue is generally examined under a microscope by a pathologist, and can also be analyzed chemically...

 of a small amount of tissue

Biological tissue

Tissue is a cellular organizational level intermediate between cells and a complete organism. A tissue is an ensemble of cells, not necessarily identical, but from the same origin, that together carry out a specific function. These are called tissues because of their identical functioning...

 for examination under a microscope

Microscope

A microscope is an instrument used to see objects that are too small for the naked eye. The science of investigating small objects using such an instrument is called microscopy...

. Also, air may be injected through the proctoscope to help make viewing easier. Similar instruments, the sigmoidoscope

Sigmoidoscopy

Sigmoidoscopy From Greek Sigma - eidos - scopy, to look inside an s-like object, is the minimally invasive medical examination of the large intestine from the rectum through the last part of the colon. There are two types of sigmoidoscopy, flexible sigmoidoscopy, which uses a flexible endoscope,...

 and colonoscope

Colonoscopy

Colonoscopy is the endoscopic examination of the large bowel and the distal part of the small bowel with a CCD camera or a fiber optic camera on a flexible tube passed through the anus. It may provide a visual diagnosis and grants the opportunity for biopsy or removal of suspected...

may be used to visualize more proximal parts of the bowels.