Rectal biopsy

Alternative names:

biopsy of the rectum

How the test is performed:

A rectal biopsy is usually part of anoscopy or sigmoidoscopy.

First, a digital rectal examination is performed. The doctor inserts a lubricated, gloved finger into the rectum to determine if anything will block the insertion of the anoscope.

A lubricated anoscope (or sometimes, a rectal speculum or proctoscope) is then inserted, which will cause some pressure. If a biopsy must be taken, it can be done through any of these scopes. The scope is a short tube with a light attached; it enlarges the rectum to allow the doctor to view the entire anal canal. Anesthetic is introduced through the anoscope, then biopsy forceps, a cytology brush, culture swab, or suction catheter is introduced through the anoscope to take a sample. Afterward, the scope is slowly removed.

How to prepare for the test:

You will need to defecate before the procedure and a laxative, enema, or other preparation may be administered.

How the test will feel:

There will be some pressure during the procedure, and you may feel an urge to defecate. A small amount of cramping sometimes occurs as the anoscope is inserted, but there should be no pain.

Why the test is performed:

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