The transrectal ultrasound of the prostate (TRUS) is a medical imaging procedure that uses high-frequency sound waves to create detailed pictures of the prostate gland and surrounding tissues. These sound waves travel through the body, bounce back as echoes, and are translated by a computer into a real-time image on a screen. This minimally invasive technique is commonly used to investigate prostate abnormalities, such as an elevated Prostate-Specific Antigen (PSA) result or an unusual finding during a digital rectal exam (DRE). TRUS helps diagnose conditions like prostate enlargement or inflammation, and it often guides more involved procedures, such as a needle biopsy.
Preparing for the Ultrasound
Proper preparation ensures the clearest possible images of the prostate for a successful TRUS. Patients are often asked to perform a bowel preparation using a small enema or laxative shortly before the procedure. This clears the rectum of stool and gas, reducing interference that could obstruct sound waves or impede the probe’s movement.
Patients must discuss all current medications with the healthcare provider, especially blood-thinning agents like aspirin or non-steroidal anti-inflammatory drugs (NSAIDs). If a biopsy is planned, these medications may need to be temporarily stopped to lower the risk of excessive bleeding. Antibiotics may also be prescribed before and after the scan to reduce the risk of infection, as the rectum is not sterile.
Instructions regarding the bladder vary, but it should generally not be completely full or empty for the scan. Patients must also follow instructions regarding food and drink, as fasting may be required if sedation or a biopsy is involved.
The Transrectal Ultrasound Procedure
TRUS is typically performed in an outpatient setting and generally lasts between 15 and 30 minutes. The patient is usually asked to lie on their side with their knees drawn toward their chest for comfortable access and easier insertion of the probe. If a biopsy is performed, a local anesthetic is injected into the prostate tissue to minimize discomfort.
The procedure begins with the gentle insertion of the specialized ultrasound probe into the rectum until it rests next to the prostate gland. The probe is covered with a protective sheath and sterile lubricating gel. Its close proximity to the prostate is necessary because the high-frequency sound waves provide high-resolution images of soft tissue.
Once the probe is in place, the sonographer or physician systematically moves and rotates the device to capture images of the entire prostate from various angles. The echoes generate a cross-sectional image on a monitor. The provider measures the gland’s dimensions to calculate its volume and checks for any abnormal areas, such as masses or asymmetry. If a biopsy is required, the ultrasound image precisely guides a fine, hollow needle to collect tissue samples.
Post-Procedure and Recovery
Following a TRUS performed without a biopsy, patients can usually return to normal daily activities immediately. The procedure is well-tolerated, and most individuals experience no side effects. Some may notice a mild feeling of pressure or minor soreness in the rectal area immediately after the probe is removed.
If the TRUS included a biopsy, recovery is slightly more involved but still low-risk. Patients should avoid strenuous activity or heavy lifting for a few days to minimize complications. It is common to see small amounts of blood in the urine or stool for a day or two, and blood in the semen can occur for several weeks.
Patients should contact their provider if they experience signs of infection, such as fever, chills, or difficulty urinating. They should also report heavy or prolonged rectal or urinary bleeding. Staying well-hydrated is encouraged to help flush the urinary system.
Understanding the Ultrasound Findings
The primary finding from a TRUS is the accurate measurement of the prostate gland’s volume and size. This measurement is important for evaluating conditions like benign prostatic hyperplasia (BPH), or prostate enlargement, and for calculating PSA density. The ultrasound images also reveal the internal structure of the prostate, providing visual evidence of its overall shape and symmetry.
The sonographer looks for areas that reflect sound waves differently than healthy tissue, which may appear as abnormal masses, nodules, or calcifications. While TRUS alone cannot definitively diagnose cancer, it can indicate suspicious areas that warrant further investigation. The findings are often used alongside other clinical data, such as PSA levels and DRE results, to create a complete picture of prostate health.
TRUS visualization is also used to guide treatments, such as planning for radiation therapy or monitoring the effects of hormone therapy. If the ultrasound confirms the presence of a suspicious lesion, the images serve as a map to guide the needle during a targeted biopsy, which is required to obtain a definitive diagnosis. The final report combines these structural findings and measurements for the physician to interpret and discuss with the patient.