NEW Technologies: In-Office Ultrasound-Guided Transperineal Prostate Biopsy
By: Andres Felipe Correa, MD; Alexander Kutikov, MD; David Y. T. Chen, MD | Posted on: 01 May 2021
Prostate cancer remains the most prevalent cancer in men, with an estimated 250,000 cases diagnosed every year in the United States.1 Despite recent advances in prostate cancer imaging with magnetic resonance imaging (MRI) and prostate specific antigen (PSA) positron emission tomography (PET), a prostate biopsy remains necessary to establish a prostate cancer diagnosis. It is estimated that over 1 million prostate biopsies are performed annually in the U.S. alone.2 Transrectal (TR) ultrasound-guided prostate biopsy has been the predominant prostate biopsy approach in the U.S. and elsewhere.2 The infectious complications associated with the TR approach have been well documented, with cystitis, prostatitis and epididymitis reported in up to 7.0% of men, and rates of post-biopsy sepsis ranging from 0.3% to 3.1%.3 The emergence of multidrug resistant organisms not only has increased the incidence and severity of of post-biopsy infections,4 but also is driving the routine use of broader spectrum antibiotics for peri-procedure prophylaxis.
In response to increasing awareness3 and scrutiny,5 the field of urology has proposed myriad quality improvement measures (rectal swabs culture, formalin needle wash, pre-procedure enema) aimed at decreasing the morbidity associated with the TR biopsy procedure. To date, the most notable development has been the adoption of the transperineal (TP) approach for prostate biopsy.6 With the TP approach, the biopsy needle is passed from a sterile surface, the prepped skin, to the prostate, significantly lowering the infectious complications associated with the procedure. Although randomized trials comparing the TR and TP approaches are limited by small sample sizes,7 the differences in infection rates are stark, with sepsis events following TP biopsies becoming a nonevent,8 even with the omission of peri-procedural prophylaxis.9 Importantly, regarding cancer detection, the transperineal approach appears comparable to the transrectal technique, with some studies suggesting an improved cancer detection rate and showing an improved sampling of anterior tumors.8,10
Despite the increasing evidence demonstrating the superiority of the transperineal approach, adoption of the technique has been languid.11 Critics of the technique argue an increased risk of acute urinary retention and the need for a systemic anesthetic (sedation or spinal) for the procedure. The increased risk of urinary retention associated with TP biopsies has been extrapolated from clinical trials12 and from historical series assessing the effectiveness of mapping biopsies (biopsy every 5 mm). With the adoption of freehand transperineal templates, which obtain 12 to 25 cores,10 the risk of urinary retention has decreased significantly (0.3%–2%) and is comparable to the rate reported with the TR prostate biopsy approach.
Adoption of in-office transperineal biopsy does require added equipment that may not be available in all urology offices. The procedure requires the patient to be placed in the lithotomy position (fig. 1, A); thus, a procedure table with stirrups is required. Additionally, a biplanar probe “side-fire” is required to appropriately track the needle in the sagittal plane (fig. 1, B and C). Historically, transperineal biopsies have been performed with the aid of a probe stabilizer, stepper and a template grid, requiring additional equipment and with samples taken through multiple independent perineal needle punctures. With the freehand technique, the TP biopsy can be done with 2 access points in the perineal skin (fig. 2), improving the patient’s comfort, with shorter procedure time and eliminating the need for additional equipment. This freehand biopsy approach can be performed in the office under only local anesthesia, with minor modification from TR biopsy. The key points to master for successful freehand transperineal prostate biopsy are correct identification of the access point, achieving adequate local anesthesia and understanding needle tracking in the perineal space.
- Selection of the transperineal access point:
Some advocate that the perineal access point is estimated by measuring 1 to 1.5 cm above the anal verge and 1 to 1.5 cm lateral. In our experience, the access point varies widely from patient to patient, mainly due to differences in prostate size and the amount of transperineal fat. To avoid several large-bore entry sites into the perineum, we use the spinal needle (at the time of local anesthesia) to identify the most appropriate site (fig. 1, D–F). In our opinion, the best perineal access point is located halfway between the urethra and the most lateral aspect of the prostate, and approximately 1.5 to 2 cm above the rectoprostatic fascia (Denonvilliers’ fascia; fig. 1, D–F).
- Local anesthesia:
We utilize approximately 30 ml 1% lidocaine mixed in a 90%/10% ratio with sodium bicarbonate. The initial 10 ml is injected bilaterally and superficially into the perineal skin just above the anal verge, extending upward and laterally. Once the skin has been anesthetized, the biplanar probe is inserted into the rectum, and the prostate sonogram is initiated per routine. Essential structures to identify during the sonogram are the urethra, rectoprostatic fascia and the levator ani musculature (fig. 1, D–F). A long spinal needle is advanced under ultrasound visualization at the midpoint between the urethra and the most lateral aspect of the prostate (fig. 1, E). The levator muscle is pierced (most sensitive portion), and the needle is advanced to the apex of the prostate (fig. 1, E and F). Ten ml anesthetic solution is delivered between the apex, the levator muscle and the subcutaneous tissue to create a deeper block. The same procedure with the final 10 ml is performed at the contralateral site.
- Needle tracking in the perineum:
Early in our experience, we utilized the PrescisionPoint™ needle access system (fig. 2) to help track the needle in the perineum. The needle access system allows for the biopsy needle to be in a fixed alignment with the ultrasound probe, facilitating needle tracking. The ease of needle tracking with the needle access system comes at the cost of a decreased degree of freedom and the need to place extra punctures in the perineum to sample the anterior aspect of the prostate and, in large glands, the peripheral wings (fig. 2). With experience, we have moved away from the needle access system and currently use a single entry site using a 14 gauge angiocath (fig. 2). Freehand guided needle tracking requires more experience without the needle access system, but it allows for greater freedom to adjust the approach, to access the anterior and most lateral aspects of the prostate. It is essential to recognize the tangential nature of the needle when using the angiocath technique, especially when targeting the lateral aspect of the prostate (fig. 2).
In summary, we expect the TP approach will supplant the traditional TR approach for routine prostate biopsy as it can result in equivalent cancer detection, and prostate biopsy-related sepsis is largely avoided using the TP approach. While there is an associated learning curve with the TP technique, as with any other procedure or technology, it is feasible as an in-office procedure under local anesthesia for the majority of men.
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