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Biopsy of the Prostate and Transrectal Ultrasound

Medically reviewed by Last updated on Feb 2, 2023.

What is the test?

Harvard Health Publishing

Your doctor is likely to recommend this test if you've had a rectal exam or blood tests that suggest that you might have prostate cancer. For this test, a urologist takes tissue samples from several places in your prostate, to be examined for cancer. A transrectal ultrasound helps the urologist see the prostate during the procedure.

There are two ways in which the biopsy can be performed. The most common uses an ultrasound and samples the prostate tissue with a biopsy needle that goes through the rectum. This is called a TRUS biopsy, or transrectal ultrasound guided biopsy. The second way of sampling the prostate tissue is by going through the area located between the bottom of the scrotum (the sac that contains the testicles) and the anus — this is called a transperineal biopsy. This article will focus on the TRUS method.

How do I prepare for the test?

Tell your doctor about all the medicines you take before scheduling the procedure. If you take aspirin, another NSAID or an anticoagulant medicine such as warfarin (Coumadin), your doctor will advise if changes need to be made for the biopsy. Be sure to mention any allergies, especially to antibiotics.

Some doctors recommend that you have an enema the night before or the morning of the test. And some doctors also recommend taking an antibiotic one hour before the procedure starts.

What happens when the test is performed?

In most cases, you lie on your side with your knees bent up to your chest. An ultrasound machine's sensor — a short rod about the width around of two fingers — is covered with a condom and clear jelly and gently inserted into your rectum. You may feel some pressure similar to the sensation before a bowel movement. Once the sensor is in place, an image of your prostate appears on a video screen.

The ultrasound sensor surveys the whole prostate gland and pinpoints specific areas for biopsy. Then the doctor may remove this ultrasound sensor and replace it with a slightly smaller one. In addition to generating an ultrasound image, the smaller sensor has a small tube on its side called a needle guide.

Your doctor points the needle guide at specific parts of your prostate. The guide releases a spring-loaded needle to take biopsies from different parts of the prostate. The spring-loading allows this needle to move into and out of the prostate very quickly. You are likely to feel some discomfort from each biopsy, but because the needle moves so quickly, any pain lasts only for a second at a time.

Doctors usually collect multiple samples. Your doctor may want you to take antibiotics after the procedure.

What risks are there from the test?

Many people have some blood in their urine or stool for several days to a week. You may also have specks of blood in the semen when you ejaculate, and this can last several weeks after the biopsy. The only significant risk is the possibility of an infection in the prostate, but antibiotics can help prevent this.

Must I do anything special after the test is over?

If your doctor prescribes an antibiotic, take it as directed. Call your doctor if you develop a fever.

How long is it before the result of the test is known?

A pathologist will examine the biopsies under a microscope for cancer. This process usually requires several days to a week.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.