What is the procedure for performing a prostate ultrasound?

Prostate Ultrasound Procedure

Transrectal ultrasound (TRUS) is the standard method for evaluating the prostate and guiding needle biopsies when prostate cancer is suspected, using a probe inserted through the rectum with frequencies of 5.0 to 10 MHz. 1, 2

Types of Prostate Ultrasound

• Transrectal ultrasound (TRUS) is the primary method used for prostate evaluation and to guide biopsies, offering detailed visualization of the prostate's internal architecture 1, 3
• Transabdominal ultrasonography can be used to assess prostate shape, size, configuration, and protrusion into the bladder when measuring residual urine 1

TRUS Procedure Steps

• Patient is typically positioned in the left lateral decubitus position with knees drawn up toward the chest 4
• A digital rectal examination is performed prior to probe insertion 4
• The ultrasound probe is covered with a condom or sheath and lubricated 4
• The probe is gently inserted into the rectum and advanced to visualize the prostate 4
• Images are obtained in multiple planes (transverse, sagittal, and coronal) to fully evaluate the prostate 4
• Prostate volume measurements are taken in three dimensions 1, 4
• If performing a biopsy, local anesthetic (typically 10cc of 1% lidocaine) is injected around the prostate approximately 10 minutes before the procedure 5
• For biopsies, an 18-gauge needle attached to a semi-automatic spring-loaded device is used under ultrasound guidance 4

Clinical Applications

• Primary use is to guide systematic biopsies when prostate cancer is suspected (rated 9/9 for appropriateness by the American College of Radiology) 1, 2
• Allows accurate measurement of prostate size and evaluation of prostate shape 1, 3
• Can identify hypoechoic lesions that may represent cancer, though with limited specificity 1, 3
• First-line imaging modality for evaluation of hematospermia 1
• Can be used to assess prostatic size and shape when planning treatments that depend on anatomical characteristics 1

Limitations and Considerations

• Conventional grayscale TRUS has poor tumor visualization with only 11-35% of tumors being sonographically visible 1, 2
• Only 17-57% of hypoechoic lesions detected on TRUS are actually malignant 1, 2
• TRUS-guided systematic biopsy has a false-negative rate of 15-46% 1
• TRUS alone (without biopsy) has low specificity and is not recommended for cancer screening 1, 3
• MRI before TRUS-guided biopsy is now recommended to identify appropriate targets for sampling using MRI-TRUS fusion technology 1

Complications and Safety

• TRUS is generally well-tolerated with minimal risk to patients 6
• Minor complications are common (63.6% of patients) but major complications are rare 7
• Most common complication is persistent hematuria (47.1% of cases), typically lasting 3-7 days 7
• Infectious complications are rare (1.7% incidence of fever) 7
• Pain during the procedure is significantly reduced with proper local anesthetic administration 5
• Younger patients may experience more discomfort during the procedure and may benefit from additional analgesia 7

Advanced Techniques

• MRI-TRUS fusion biopsies combine multiparametric MRI with TRUS to target specific lesions, improving detection of clinically significant cancers 1, 2
• Advanced ultrasound techniques such as Doppler, 3D ultrasound, microbubble contrast-enhanced ultrasound, and elastography show potential for improving TRUS performance 1