What is a prostate/rectal ultrasound?

A prostate or rectal ultrasound is an imaging test that uses sound waves to look at your prostate or rectum.

The healthcare provider uses a small probe called a transducer to make images of your prostate or rectum. The transducer is about the size of a finger. It's gently placed into your rectum, where it sends out sound waves that bounce off your organs and other structures. The sound waves are too high-pitched for you to hear. The transducer then picks up the bounced sound waves. These are made into pictures of your organs.

Your provider can add another device called a Doppler probe to the transducer. This probe lets your provider hear the sound waves the transducer sends out. They can hear how fast blood is flowing through a blood vessel and in which direction it is flowing. No sound or a faint sound may mean that you have a blockage in blood flow.

Why might I need a prostate/rectal ultrasound?

A prostate/rectal ultrasound may be used to check the size, location, and shape of the prostate gland and nearby structures. It may be used to look at the prostate gland for signs of cancer or other conditions. It’s often the next step after a finding of raised (elevated) prostate-specific antigen (PSA) blood test. Prostate/rectal ultrasound may be used to stage and watch treatment of rectal cancer. It's also used to look at the rectum for other problems.

Your healthcare provider may also use a prostate/rectal ultrasound to help place a needle to take a tissue sample (biopsy), which will be checked under a microscope in a lab. Or they may do it to help place radiation seeds used to treat prostate cancer.

Your provider may also use the test to see how well blood is flowing to the prostate. Or to find detect abnormal growths in the prostate.

Your provider may have other reasons to advise a prostate/rectal ultrasound.

What are the risks of a prostate/rectal ultrasound?

An ultrasound has no risk from radiation. Most people have mild discomfort from the transducer being placed in the rectum.

Tell your healthcare provider if you're allergic to latex. The probe is placed in a latex covering before it's put into the rectum.

You may have risks depending on your specific health condition. Be certain your provider knows about all of your health conditions before the procedure.

Too much stool in the rectum may make the test less accurate.

How do I get ready for a prostate/rectal ultrasound?

• Your healthcare provider will explain the procedure and you can ask questions. Make a list of questions and any concerns to talk about with your provider before the procedure. Think about bringing a family member or trusted friend to the medical appointment. They can help you remember your questions and concerns.  

• You'll be asked to sign a consent form that gives your permission to do the procedure. Read the form carefully. Ask questions if something isn't clear.

• You may be asked to stop taking blood-thinning medicines, such as aspirin, for 7 to 10 days before the test if it's being done as part of a biopsy. You may also be instructed to use an enema for bowel cleansing and take antibiotics if a biopsy is planned.

• Follow all directions you're given for not eating or drinking before the test.

• Follow any other instructions your provider gives you to get ready.

What happens during a prostate/rectal ultrasound?

You may have a prostate/rectal ultrasound done as an outpatient. This means you go home the same day. Or it may be done during a hospital stay. The way the test is done may vary depending on your condition and your healthcare provider's practices.

Generally, a prostate/rectal ultrasound follows this process:

1. You'll need to remove any clothing, jewelry, or other objects that may get in the way of the procedure.

2. If asked to remove clothing, you'll be given a gown to wear.

3. You'll lie on an exam table on your left side with your knees bent up to your chest.

4. The healthcare provider may do a digital rectal exam before the ultrasound.

5. The provider puts a clear gel on the transducer and puts the probe into the rectum. You may feel a fullness of the rectum at this time.

6. The provider will turn the transducer slightly several times to see different parts of the prostate gland and other structures.

7. If blood flow is being looked at, you may hear a whoosh, whoosh sound when the Doppler probe is used.

8. Once the test is done, the provider will wipe off the gel.

A prostate/rectal ultrasound may be uncomfortable. You'll need to remain still during the test. The gel will also feel cool and wet. The technologist will use all possible comfort measures and do the scan as quickly as possible to minimize any discomfort.

What happens after a prostate/rectal ultrasound?

You don't need any special care after a prostate/rectal ultrasound. In rare cases, a small amount of blood may be present in the semen or urine after the procedure. You may go back to your normal diet and activities unless your healthcare provider tells you otherwise.

Next steps

Before you agree to the test or the procedure, make sure you know:

• The name of the test or procedure

• The reason you are having the test or procedure

• What results to expect and what they mean

• The risks and benefits of the test or procedure

• What the possible side effects or complications are

• When and where you are to have the test or procedure

• Who will do the test or procedure and what that person’s qualifications are

• What would happen if you did not have the test or procedure

• Any alternative tests or procedures to think about

• When and how you will get the results

• Who to call after the test or procedure if you have questions or problems

• How much you will have to pay for the test or procedure