A transrectal ultrasound (TRUS) of the prostate may also be called a prostate sonogram or endorectal ultrasound. A doctor usually performs a TRUS to help diagnose prostate cancer or detect prostate disorders.

A doctor uses a probe known as an ultrasound transducer to send sound waves through the rectal wall and into the prostate and tissue around the rectum.

As the sound waves bounce off the organs, a computer analyzes the echoes and uses them to produce an image. The procedure can provide clear images of soft tissue that an X-ray might not be able to provide.

A TRUS does not use ionizing radiation and does not typically cause health issues.

This article discusses the purpose, preparation, and procedure for a TRUS. It also looks at what the results may mean, next steps, benefits, risks, and limitations of the procedure, and offers guidance on costs and financial help.

An ultrasound of the prostate -2.Share on Pinterest
alex-mit/Getty Images

Often, a doctor will perform a TRUS to help diagnose an issue that affects the prostate. The prostate, which forms part of the male reproductive system, is a small gland in front of the rectum that helps produce semen.

This may include:

A doctor may perform a TRUS to pursue a diagnosis for various reasons, which include following up if a person:

A doctor may also perform a TRUS to help guide a needle during a prostate biopsy to help them gather a tissue sample.

In preparation for a TRUS, a doctor may advise:

  • stopping certain blood-thinning medications 7–10 days before the procedure
  • receiving an enema before the procedure
  • emptying their bladder shortly before the procedure

A doctor usually performs a TRUS in an outpatient clinic or doctor’s office.

Before it begins, a doctor may numb the area. The sensation of the probe, or transducer, may be uncomfortable, but it is not usually painful.

For the procedure, the person lies on their side with their knees bent toward their chest. The doctor lubricates the transducer — about the width of a finger — and inserts it into the rectum. The person may experience a feeling of fullness or pressure in the rectum once the probe is in place.

A TRUS typically takes less than 10 minutes but may take 15–30 minutes.

After the procedure, a radiologist — a doctor with expertise in supervising and interpreting radiology exams — will examine the images.

The radiologist will send their report of the images to the doctor who requested the procedure.

Routine results will reveal a healthy prostate that is not enlarged and does not contain growths, lesions, or other abnormalities.

If the results of the TRUS are atypical, it could indicate that the person has:

If the results of a TRUS reveal abnormal results, a doctor may request a follow-up exam, which may involve further ultrasound imaging or different imaging techniques, such as MRI.

A doctor may also refer the individual to a urologist, which is a doctor who specializes in the treatment of urinary tract conditions.

If a doctor suspects a person has an enlarged prostate, they may recommend medication or surgery.

If a doctor suspects prostate cancer, they may order a biopsy. In a biopsy, the doctor places a thin, hollow needle alongside the ultrasound probe and pushes the needle through the wall of the rectum and into the prostate.

The doctor uses the hollow needle to collect 10–12 tissue samples from different areas of the prostate. The doctor sends the samples to a laboratory so the pathologist can examine the tissue for cancer cells or other abnormalities.

Doctors do not associate a TRUS with any risks.

Some people are not ideal candidates for transrectal ultrasounds, such as people who have undergone surgery to remove the end of their bowel.

In such cases, a radiologist may try to view the prostate by placing the probe on the perineal skin, but the images it produces may not be as detailed as they would be with a transrectal probe.

Ultrasound imaging techniques are typically more cost-effective than other types of imaging.

Based on Medicare national averages from 2022, the cost of a transrectal ultrasound is as follows:

Ambulatory surgical centersHospital outpatient departments
Total cost$88$143
Doctor fee$32$32
Facility fee$56$111
Medicare pays$71$114
Person pays$17$28

In a TRUS, a doctor inserts a probe into the rectum, which sends sound waves through the rectal walls to the prostate and surrounding tissue.

The sound waves bounce off the organs, and a computer interprets and forms these waves into an image, allowing doctors to view the prostate.

A doctor will typically perform a TRUS to help them diagnose an issue with the prostate, such as enlargement or cancer. A doctor may also use an ultrasound to help guide a needle into the prostate for a biopsy.