A transrectal ultrasound (TRUS) is a specialized scan that uses sound waves to create detailed, close-up images of your prostate gland. The prostate is a small, walnut-sized gland in men located just in front of the rectum. Because it sits deep in the pelvis, standard abdominal scans can struggle to see it clearly.
By inserting a slender, lubricated probe into the rectum, the radiographer can place the ultrasound sensor right next to the prostate gland, obtaining extremely sharp images of its structure.
Common Indications for a Transrectal Ultrasound (TRUS)
- Investigating abnormal findings from a digital rectal exam (DRE) or high blood test results (PSA).
- Guiding a needle biopsy to test for prostate cancer.
- Evaluating a suspected prostate infection or abscess (prostatitis).
- Investigating issues with male infertility (checking for blocked ducts).
- Determining the exact size of the prostate to plan treatments for an enlarged prostate (BPH).
What exactly does a transrectal ultrasound (TRUS) show?
The scan shows the size, shape, and internal structure of the prostate gland and the surrounding tissues, including the seminal vesicles. It can identify solid nodules, fluid-filled cysts, areas of infection, or signs of enlargement.
How should I prepare for a transrectal ultrasound (TRUS)?
Preparation varies, but you may be asked to use a mild enema (laxative) a few hours before the scan to empty your lower bowel. This ensures a clear view. If the scan includes a prostate biopsy, you may be asked to start taking antibiotics beforehand and stop taking blood thinners.
Do I need to stop taking medication?
For a diagnostic ultrasound alone, you do not need to stop medications. If you are having a biopsy guided by the ultrasound, you must discuss stopping blood-thinning medications (such as aspirin or warfarin) with your referring doctor.
What happens when I arrive for my scan?
You will go to a private scan room. You will undress from the waist down and change into a hospital gown. The radiographer will ask you to lie on your left side on the scan couch, with your knees bent up toward your chest.
How is the procedure performed?
The doctor will perform a quick physical digital rectal exam first. Then, they will place a sterile sheath and warm gel over a slender, specialized probe. The probe is gently inserted into your rectum. You will feel a sensation of fullness. The doctor will move the probe slightly to capture images of the prostate from various angles. If a biopsy is needed, a tiny needle will be passed through the probe to collect tissue samples.
How long does a transrectal ultrasound (TRUS) take?
A diagnostic scan takes about 15 to 20 minutes. If a biopsy is being performed during the scan, the procedure takes about 30 minutes.
Is there any discomfort?
Yes. You will feel a feeling of pressure and fullness in your rectum as the probe is inserted and adjusted. While it is uncomfortable and may feel like you need to have a bowel movement, it is generally not painful. Try to take slow, deep breaths to help relax your muscles.
Are there risks?
For the scan alone, there are virtually no risks. If a biopsy is performed, there is a small risk of temporary bleeding (blood in your urine, stool, or semen for a few weeks) and a small risk of infection, which is managed with preventative antibiotics.
Can children have this scan?
This scan is performed almost exclusively on adult men.
Can I have this scan if I am pregnant?
This scan is only performed on male patients.
When will I get my results?
A radiologist will review the images. The report will be sent to your referring doctor within 24 hours. If a biopsy was performed, the tissue samples will be sent to a pathologist, and those results usually take 5 to 7 days.
What if the scan finds something?
If the scan shows an abnormality or enlargement, your referring doctor (a urologist) will discuss treatment options. If a biopsy confirms cancer, they will guide you through options like active surveillance, surgery, or radiation therapy.
What are the important limitations?
Ultrasound does not use ionising radiation, but a useful result still depends on the clinical question, the operator, the equipment, patient anatomy, and whether the target can be reached by sound waves. Gas, bone, body habitus, pain, movement, and a limited acoustic window can hide disease. A normal scan does not automatically exclude the suspected condition; persistent or worsening symptoms need clinical reassessment and sometimes repeat ultrasound, CT, MRI, laboratory tests, or another specialist test.
Ultrasound should be used for a medical purpose, with output and examination time kept as low as reasonably achievable—especially in pregnancy and with Doppler. Internal scans and procedures require explanation, consent, privacy, and a chaperone according to patient preference and local policy.
Questions to ask your care team
- What exact question should this ultrasound answer, and could anything important remain unseen?
- Is this a screening, diagnostic, surveillance, or procedure-guidance examination, and will the result change care?
- What preparation is required, and should I continue all medicines unless my own clinician gives different instructions?
- When will I receive the signed report, who will explain it, and what symptoms should prompt urgent assessment rather than waiting?
Sources and further reading
Conclusion
A transrectal ultrasound is a safe and vital tool for diagnosing prostate conditions. To make the scan more comfortable, try to remain as relaxed as possible and breathe deeply during the probe insertion.