A rectal biopsy is a procedure to remove a small piece of rectal (anal) tissue for examination.

A rectal biopsy is usually part of anoscopy or sigmoidoscopy.

A digital rectal exam is first done to make sure there isn't anything blocking the rectal area. After this is done, a lubricated instrument (anoscope, rectal speculum, or proctoscope) is placed into the rectum. You will feel some pressure when this is done.

A biopsy can be taken through any of these instruments.

A laxative, enema, or other preparation may be given prior to the biopsy so that you can completely empty your bowels.

There will be some pressure during the procedure, and you may feel an urge to have a bowel movement. A small amount of cramping sometimes occurs as the instrument is placed into the rectal area, but there should be little pain.

A rectal biopsy is used to determine the cause of abnormal growths found during anoscopy, sigmoidoscopy, or other tests. It can also be used to confirm the diagnosis of amyloidosis.

The anus and rectum appear normal in size, color, and shape. There should be no evidence of bleeding, polyps, hemorrhoids, or other abnormalities. On microscopic examination of biopsy tissue, no abnormalities should be noted.

This test is one of the more common means to confirm amyloidosis. It also determines the specific causes of abnormal conditions of the rectum, such as colitis. Other findings could include colorectal polyps, abscesses, inflammation, infection, hemorrhoids, or tumors.

Additional conditions under which the test may be performed include the following:

• Hirschsprung's disease
• Ulcerative colitis
• Crohn's disease

There is some risk of bleeding, pain, and perforation. Occasionally, patients have problems with urinary retention after rectal biopsy.