A safe and accurate biopsy technique is essential for the management of prostate cancer. Patients are selected for biopsy based on a complex algorithm of their PSA and kinetics, DRE finding, age and comorbidities, individual risk factors for cancer, including family history, patient concern of cancer, preoperative MRI findings, or a prior diagnosis of prostate cancer with the patient on an active surveillance program. Favoring a transperineal route for biopsy include patient concern for infection (or risk factors thereof), or where patients have had a prior negative TRUS biopsy but there remains a high index of clinical suspicion of a missed anterior cancer.
Various schemes have been described over time, with the early finger-guided transperineal sextant biopsies giving way to transrectal ultrasound-guided (TRUS) biopsies more recently. However, the risk of enteric flora translocation via the transrectal route is a persistent safety issue, growing only more important with increasing antibiotic resistance. The advent of template-guided transperineal biopsy now permits a way to sample the whole prostate accurately and cleanly. Using a transrectal ultrasound probe, the prostate is able to be visualized throughout, with the imaging guiding a transperineal needle on its approach to the prostate, avoiding contamination from the rectal carriage entirely. New technology developments include real-time fusion of ultrasound and MRI data, permitting targeted biopsy of (suspicious) high PI-RADS score regions. Increasingly MRI is being used before biopsy to establish the need to biopsy, and also to direct the biopsy, as well as indicate the likelihood of a positive biopsy (pretest probability, using the PI-RADS system).
Although the learning curve for this technique is not well documented, the authors have found that around 50 cases are required for consistent results. These numbers will be less for clinicians who have experience with brachytherapy.
Preoperative Preparation and Planning
Owing to the patient position for the biopsy and cutaneous sensation at the perineum, transperineal biopsy is typically performed under general anesthesia in a day procedure unit. All patients are ensured to have a sterile preoperative urine culture. On the day prior to the procedure, men commence a 3-day course of oral fluoroquinolone prophylaxis, with norfloxacin (400-mg twice-daily) preferred in our institution. Additionally, patients are administered with perioperative intravenous ceftriaxone.
Specific equipment requirements for biopsy include YelloFins (Allen Medical Systems, Acton, MA) or similar to permit placement of patient into the lithotomy position.
Attached to the operating table is a stepper , which holds both the brachytherapy grid and ultrasound probe in a fixed position against the perineum. Stepper design has evolved significantly over time, with recent models offering improved ergonomics and ease of use. Favored are devices that only require one point of fixation to the operating table, multiple points of articulation for multiple degrees of freedom, and a pistol-grip for easy engagement / disengagement ( Fig. 74.1 ).
A biplanar transrectal ultrasound probe (7.5 MHz) and monitor permits real-time visualization of the prostate and biopsy needle. Some clinicians use higher-megahertz probes, though 7.5 remains the most commonly used ( Fig. 74.2 ).
The brachytherapy grid permits a systematic approach to biopsies. The standard grid is 6 × 6 cm, with 5-mm increments between openings, giving 13 points per axis and 169 total openings ( Fig. 74.3 ).
Biopsies are obtained using a 18-G Tru-Cut biopsy needle .
Patient Positioning and Surgical Incision
With the patient under general anesthesia, the patient is moved from the supine into the dorsal lithotomy position. A digital rectal examination is routinely performed prior the placement of the probe for a more accurate assessment of the prostate.
To expose the perineum the scrotum is elevated, either with passive support from the patient’s own hand or with use of fixative tape.
The perineum is prepped with betadine (10% povidone-iodine). Although sterile leg draping is placed in some institutions, its routine use is not required ( Fig. 74.4 ).
The stepper is then fixed to the bed, ultrasound probe fitted and aligned for entry into the rectum ( Fig. 74.5 ).
Ensure the patient is adequately anesthetized before starting the biopsy process, as if the patient is too light then the patient may experience discomfort/awareness. Furthermore, the patient can move from the pain, resulting in damage to the probe or stepper.
Biopsies are performed with the patient in a dorsal lithotomy position under general anesthesia. It is important to ensure adequate lubricating jelly is placed in the rectum.
With the ultrasound probe fixed to the stepper, the rectum is slowly entered using constant light pressure until it accommodates. The probe is then advanced backward and forward (rostrally and caudally) to ensure that the prostate is fully visualized along its length. Identify the critical landmarks, particularly the urethra, the apex, the presence of a middle lobe, and the seminal vesicles. After landmarks are identified, look carefully for obvious hypoechoic abnormalities that may correlate with prebiopsy MRI or digital rectal examination findings.
If the apex of the prostate is unable to be imaged, usually in high-arched rectums, it may be necessary to use more lubricating gel to increase contact between probe and rectal wall, as well as change the angle of the probe relative to the rectum. Moving the probe backward and forward helps to eliminate air between probe and prostate, which also impacts upon clear visualization with artifact. With the patient appropriately positioned, the gland is measured ( Fig. 74.6 ).