A prostate ultrasound uses high-frequency sound waves to create detailed pictures of the prostate gland and surrounding tissues. This procedure is most commonly performed as a transrectal ultrasound (TRUS), providing physicians with a close-up view of the small gland located beneath the bladder and in front of the rectum. The scan evaluates the gland’s structure, size, and texture for various health concerns.
How the Ultrasound Works
The technology behind this imaging technique relies on a small device called a transducer, which functions as both a sender and receiver of sound waves. This probe emits high-frequency sound waves into the body’s soft tissues. As these waves encounter different structures, such as the prostate tissue, they bounce back as echoes.
The transducer captures these returning echoes, and a connected computer translates the patterns into a real-time, two-dimensional image displayed on a monitor. Because the prostate is positioned close to the rectum, the transrectal approach allows the transducer to be placed directly against the rectal wall, providing clear visualization of the gland. This proximity enables the accurate assessment of the prostate’s internal structure without using ionizing radiation.
Why Doctors Order This Scan
Physicians often recommend a prostate ultrasound to investigate potential issues with the gland. A common indication is an elevated or rapidly rising level of Prostate-Specific Antigen (PSA) detected in a blood test. High PSA levels can signal conditions like inflammation, enlargement, or prostate cancer, prompting closer examination.
The scan is also frequently ordered after a doctor detects an abnormality, such as a firm area, lump, or asymmetry, during a Digital Rectal Exam (DRE). The ultrasound helps map the exact location and characteristics of these palpable changes. Furthermore, the test precisely measures the size and volume of the prostate, which is necessary for diagnosing and managing Benign Prostatic Hyperplasia (BPH), a non-cancerous enlargement common in older men.
The ultrasound’s primary role is guiding a prostate biopsy. The real-time imaging allows a physician to accurately steer a fine needle to collect tissue samples from specific, suspicious areas of the gland. This technique, known as a TRUS-guided biopsy, ensures that samples are taken from the correct regions for laboratory testing.
Patient Preparation Steps
Preparation for a transrectal ultrasound focuses primarily on ensuring the rectum is clear for optimal imaging. Patients are typically instructed to perform a bowel cleanse at home using a small enema or mild laxative a few hours before the scheduled appointment. This step clears the lower rectum, minimizing interference with sound waves and improving image clarity.
If the procedure includes a biopsy, patients must discuss their current medications with their physician beforehand. They are usually advised to temporarily stop taking blood-thinning medications, such as aspirin, for about a week prior to the scan. This measure reduces the risk of excessive bleeding during tissue sampling. Patients generally do not need to fast, but some doctors may ask them to avoid eating for a few hours before the test.
Details of the Examination
The transrectal ultrasound procedure is typically performed in a urologist’s office or an outpatient clinic and is usually completed within 15 to 30 minutes. The patient changes into a gown and lies on the examination table, most often on their side with their knees bent toward their chest. This position, known as the left lateral decubitus position, facilitates the gentle insertion of the probe.
The physician or technician first covers the finger-sized transducer with a protective sheath and applies sterile lubricating gel. The probe is then gently inserted a short distance into the rectum. Patients commonly report feeling a sensation of pressure or fullness, similar to needing a bowel movement, rather than sharp pain.
Once the transducer is correctly positioned, the physician systematically rotates and angles the probe to capture cross-sectional images of the entire prostate gland and the seminal vesicles. The images are analyzed in real-time, allowing the doctor to measure the prostate and note any abnormal areas. If a biopsy is performed, the procedure may take slightly longer, and a local anesthetic may be administered before tissue samples are collected. After the examination is complete, the probe is removed, and the patient can immediately resume normal activities, with results typically being processed and reviewed by a radiologist or urologist over the following days.