The first transrectal core needle prostate biopsy was first reported by Astraldi and colleagues in 1937. Since that time, advances in our understanding of prostatic zonal anatomy, ultrasound imaging, and the development of a spring-loaded core biopsy device have resulted in the modern transrectal ultrasound (TRUS)–guided prostate biopsy technique. Currently, TRUS-guided prostate biopsy remains the gold standard for diagnosis of prostate cancer.
Indications
The decision to proceed to prostate biopsy is quite complex with myriad factors to consider, including digital rectal exam findings, prostate volume, serum prostate-specific antigen (PSA), PSA kinetics, percentage free PSA, patient life expectancy, age, family history, race, alternative biomarkers, and MRI findings among others. Development of biomarkers to better predict aggressive versus indolent prostate cancers is currently underway and may help identify patients with higher probability of high-risk prostate cancer detection. Urologists should have thorough discussion of the risks of TRUS-guided prostate biopsy and implications for treatment of prostate cancer should a diagnosis of prostate cancer be made prior to making the decision to proceed to TRUS-guided prostate biopsy.
Preprocedural Management
Antibiotics
Patients should undergo preprocedural antibiotic administration with a fluoroquinolone, or /third-intramuscular (IM)/intravenous (IV) first-, second-, or third-generation cephalosporin (if penicillin allergic trimethoprim-sulfamethoxazole, or an aminoglycoside should be administered). Antibiotics should be continued for up to 24 hours post procedure.
Choice of antibiotics should be tailored to local antibiotic resistance patterns, and duration of antibiotic should be extended if patients are at high risk for development of prostatic infection (i.e., repeat biopsy). Rectal swabbing and culture to assess for antibiotic-resistant rectal flora and bowel preparation/enema to sterilize the bowel are practices often used by some urologists to reduce risk of postbiopsy prostate infection.
Equipment
TRUS Probe
Transrectal ultrasonography is performed using a cylindrical probe, which generates frequencies between 6 and 10 MHz, allowing for 180-degree visualization of the prostate in transverse and sagittal views ( Fig. 73.1 ). The trajectory of the prostate biopsy needle can be overlaid onto the prostate images. Newer biplane models allow for simultaneous visualization of the prostate in transverse and sagittal views.
Current commercially available probes have a needle guide in either a side-fire or end-fire configuration ( Fig. 73.2 ) . Current ultrasound machines have preprogrammed, optimized settings for prostate biopsy, and tools that aid in measurement of prostate volume.
Resolution and depth of penetration are inversely related and can be influenced by changing the ultrasound frequency. Ultrasound frequencies around 7 MHz will allow for visualization at a depth of 1–4 cm, which is optimal for prostate imaging. Images obtained with lower frequencies will have a lower resolution but higher depth of penetration.
Prostate Biopsy Device
The prostate biopsy device consists of two needles, which are individually spring loaded ( Fig. 73.3 ). The inner needle has a tapered tip with a notched groove, which is used to capture the prostate tissue. The outer needle is hollow and surrounds the inner needle.
When the biopsy trigger is engaged, the inner needle advances 23 mm followed by the outer hollow needle fractions of a second later. The urologist must anticipate advancement of 23 mm to avoid unnecessary advancement of the needle into the adjacent structures like the bladder. The prostate tissue is trapped in the notch of the inner needle. To retrieve the specimen, the outer hollow needle must be retracted and the prostate tissue must be removed from the notch of the inner needle. The prostate biopsy specimen should be 15–17 mm.
Surgical Procedure, 12-Core Prostate Biopsy
Setting
TRUS-guided prostate biopsy is most commonly performed in an office-based setting; however, it can be performed under light sedation in the operating room for patients who are unable to tolerate biopsy in the office setting.
Positioning
The patient is placed in the left lateral decubitus position. The patient’s anal verge should be positioned at the edge of the table to allow for maximal mobility of the TRUS probe. The patient should have his knees and hips flexed at 90 degrees to maximally expose the anal verge.
Placement of intrarectal lidocaine lubrication should be placed several minutes prior to the procedure.
A prebiopsy digital rectal exam should be performed at the start of the procedure. Any nodular areas should be noted and biopsy should be directed at them.
Probe Insertion and Orientation
The TRUS probe should be slowly inserted with constant pressure to slowly dilate the anal sphincter and should be directed toward the patient’s spine.
The ultrasound needle direction trajectory overlay setting should be turned on. The ultrasound view should be switched between axial and sagittal to allow for accurate localization of prostate biopsy sites.
With side-fire TRUS probes, twisting of the probe allows for medial-lateral visualization of the prostate. Clockwise rotation of the probe provides visualization of the left side of the prostate, whereas counterclockwise rotation provides visualization of the right prostate ( Fig. 73.4 ) .
