This page was reviewed under our medical and editorial policy by

Chukwuemeka Obiora, MD, Surgical Oncologist

This page was reviewed on April 7, 2023.

A proctoscopy, also known as a proctosigmoidoscopy or rigid sigmoidoscopy, is a procedure that uses a proctoscope to view the inside of the rectum and anus. Measuring about 6 inches long, the rectum is the lowest part of the colon (large intestine), which holds waste, or stool, and ends at the anus. The anus is the opening that leads out of the body.

A proctoscope is a thin, hollow tube about 10 inches long with a light and camera at the end. The proctoscope is rigid, meaning it doesn’t bend. During the procedure, the proctoscope is inserted through the anus in order to closely examine the insides of the rectum and anus.

This guide will cover these common questions:

Why is a proctoscopy done?

A proctoscopy may be performed to diagnose problems or conditions affecting the rectum or anus, such as:

  • Tumors, rectal polyps, sources of inflammation and bleeding
  • Hemorrhoids
  • Reasons for diarrhea or constipation
  • Rectal cancer (for screening or treatment monitoring purposes)

As it relates specifically to rectal cancer, a proctoscopy may be needed for the reasons below.

Screening tests

Screening tests help detect cancer early and improve the rate of cancer survival. A proctoscopy may be used as a way to screen for rectal cancer. Rectal cancer is diagnosed when a growth of abnormal cells has been detected in the rectum. Most cancers start as small growths and lesions, or polyps. Polyps may be raised or indented and may be rooted by a stalk (as in pedunculated polyps), or grow along the surface of the rectum lining (as in sessile polyps).

Cancer diagnosis

During the proctoscopy, the proctoscope finds and removes potential polyps so they may be biopsied. A biopsy is the removal of a tissue for further evaluation. Typically, the tissue is viewed under a microscope to detect the presence of cancerous or abnormal cells. The tissue may also be tested for gene changes and mutations, which may help determine which medications to recommend to help treat the cancer.

Cancer staging

Proctoscopy may also be used to stage rectal cancer. The proctoscope views and measures any polyps or tumors and determines their exact location. This information is needed to stage the cancer (determining the cancerous tissue size and checking to see whether it’s spread to the lymph nodes and/or other organs), and determine the treatment plan and prognosis.

The stages of rectal cancer range from stage 0 to stage 4:

  • Stage 0: This is the earliest stage, sometimes called precancer, where there’s a small amount of abnormal cells in the inner lining of the rectum.
  • Stage 1: Cancer cells have invaded the inner layer and the thin muscle layer of the rectum, but not the lymph nodes or distant organs (such as the lungs or liver).
  • Stage 2: Cancer cells have invaded just past the border of the rectum, but not the lymph nodes or distant organs.
  • Stage 3: Cancer cells have spread past the border of the rectum, and one to six lymph nodes near the rectum are affected, but the cancer hasn’t spread to distant organs.
  • Stage 4: Cancer has spread to other parts of the body and may or may not have spread to nearby lymph nodes.

Cancer treatment

Stage 0 rectal cancer may be treated by removing polyps from the affected area, which may be removed during a proctoscopy. Rectal cancers in stages 1 through 4 require treatment beyond the proctoscopy procedure.

How do I prepare for a proctoscopy?

Ideally, the inside of the rectum would be thoroughly cleaned out so the doctor can examine the area during a proctoscopy. Although a proctoscopy does not require a full bowel prep (e.g., with laxatives), specific instructions for preparation are often given prior to the procedure.

The patient may be asked to clear the rectum or may be given an enema or glycerin suppository prior to the procedure to help facilitate emptying. An enema is performed by placing liquid into the rectum through the anus. The liquid may be water, or it may contain medication. The liquid is held in the rectum for a recommended amount of time until a bowel movement occurs. During this process, it’s helpful for the patient to stay near the toilet for up to an hour after using an enema, since it may cause more than one bowel movement.

What should I expect from the procedure?

A proctoscopy is performed in a hospital or outpatient center. Before the procedure starts, the patient will put on a gown and be instructed to lie on his or her side with the knees to the chest.

First, the doctor will insert a gloved and lubricated finger in the anus to perform an exam. Then, the proctoscope will be inserted in the anus. While the test is being performed, the patient may feel like he or she needs to have a bowel movement. This sensation is due to air being inserted by the scope to promote better visibility of the rectum.

The air in the bowels may cause a bit of discomfort, such as cramping or bloating. Otherwise, the procedure is typically not painful. Anesthesia isn’t usually required for the procedure, which routinely takes about 10 to 20 minutes to perform. The patient may resume regular activity after a proctoscopy.

Complications and side effects

Overall, little risk is involved with a proctoscopy. Some side effects may include:

  • Bleeding lightly a few days after the procedure (if bleeding continues beyond a few days, or if there is a large amount of blood in the stool, it may be necessary to follow up with a health care provider.)
  • Slight abdominal discomfort

Patients who experience these more rare outcome should call the doctor:

  • Abdominal pain
  • Dizziness
  • Weakness
  • Fever of 100 F or greater

Infection and rare tears in the rectum may also occur.

How is a proctoscopy different from other procedures?

While a proctoscopy is similar in some ways to other endoscopic procedures (by using a tubular instrument, for example), they are also different. The procedures visualize different parts of the gastrointestinal tract and may be chosen according to the part of the intestine that needs to be viewed. Other endoscopic procedures include those listed below.

Flexible sigmoidoscopy

A flexible sigmoidoscopy is also able to see the sigmoid colon and rectum. However, the procedure uses a flexible, lit tube, rather than a rigid one. The tube is about the width of a finger and, similar to the rigid sigmoidoscopy tool, has a camera on the end so the medical team can view inside the rectal area. The 2-foot-long scope is inserted into the anus, then through the rectum and into the lower colon. Because of the instrument’s shorter length, the medical team may only view as far as the lower half of the colon, but they can see the entire rectum. During the procedure, the doctor will view images from inside the body on a screen and remove any suspicious tissue for further inspection. According to the American Cancer Society, this procedure isn’t widely used as a screening tool for colorectal cancer in the United States.

Because the scope bends, it may cause less discomfort than the rigid sigmoidoscopy. Research indicates those who were screened for rectal cancer using flexible sigmoidoscopy were less likely to develop colorectal cancer than those who didn’t undergo screening.


Proctoscopy examines the anus and rectum, while a colonoscopy uses a colonoscope to view the entire colon. Like the proctoscope, a colonoscope is a thin, hollow tube that’s inserted in the anus. However, it’s flexible and is much longer so that it may see all parts of the colon. The colon is the first part of the large intestine. About 5 feet long, the colon removes water, electrolytes and some nutrients from digested food. The colonoscopy is used to screen for colon cancer.

More preparation is required for a colonoscopy, as it’s a more invasive procedure than the proctoscopy. Preparation prior to this procedure includes:

  • A special diet
  • Adjustments to prescribed medications
  • Emptying of the bowels by use of laxatives and/or enemas

During the colonoscopy, unlike typical proctoscopy procedures, sedation is used, which may make recovery take longer than it does with a proctoscopy.


The anoscopy uses a shorter scope than the one used in a proctoscopy, and it may not be able to see the entire rectum. An anoscopy would be used for viewing only the anus and the first part of the rectum.

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