AquaBeam® Robotic System components: (a) rolling equipment stand; (b) conformal planning unit (CPU; monitor), console, motorpack, robotic handpiece articulating arm, TRUS articulating arm; (c) robotic handpiece; (d) catheter tensioning device; (e) foot pedal. (Courtesy of AquaBeam®, Procept BioRobotics, Redwood Shores, CA, USA)
Equipment required
Transrectal ultrasound system with biplane (side-fire) (TRUS) probe
Cystoscope camera compatible with AquaBeam® Scope, light source, and video monitor
Saline
Drapes for patient and equipment
Others, including ultrasound lubricant, evacuation syringe, hematuria urinary catheter, etc.
Surgical Technique
Transrectal and Transurethral Insertion
The rectal ultrasound probe is inserted into the patient using an articulating arm and TRUS stepper. Insertion occurs with transverse plane views, and the probe is advanced 2–3 cm beyond any prostatic tissue with the stepper guidance. Once in the appropriate fixed position, the ultrasound is switched to sagittal view for handpiece insertion. The surgeon then inserts the AquaBeam® Robotic System handpiece transurethrally under cystoscopic visualization. Once inserted into the bladder, the surgeon docks the handpiece assembly onto the handpiece articulating arm, which holds the device in place. The handpiece should be positioned anteriorly and centered on the midline of the prostate to maximize tissue resection. The integrated scope within the handpiece is then retracted and positioned proximal to the external sphincter, protecting the sphincter. It is important to have an optimized TRUS Image for the procedure and with the handpiece positioned correctly, the ultrasound probe may need to be repositioned for optimal imaging. The ultrasound probe and handpiece should be co-linear to one another when looking down at the instruments as they are placed in the patient.
Waterjet Alignment and Angle Planning
Viewing in the ultrasound transverse plane image on the robot monitor, the waterjet is aligned so that it fires along a 180° angle on both the left and right sides. Rotation of the waterjet is achieved by manipulating rotational adjuster on the handpiece articulating arm. Following handpiece positioning, the surgeon retracts the TRUS from the bladder neck towards the apex, locating the largest cross-section of the prostate. At the mid-prostate, the surgeon uses the robot monitor and keyboard to plan the angle of resection by manipulating the angle planning tool to conform to the size of the adenoma. The surgeon can also plan angles for the bladder neck and median lobe cross-sections to optimize conformal treatment of the prostate. This conformal planning can also include planning to resect an intravesical middle lobe safely.
Waterjet Registration and Contour Planning
Aquablation contour planning. Planning is performed with both scope and ultrasound in a fixed position and views obtained in the sagittal and transverse views with the scope centered and in view on ultrasound. Contour planning can include the intravesical middle lobe as shown in these console views. (Courtesy of AquaBeam®, Procept BioRobotics, Redwood Shores, CA, USA)
Treatment
With the contour planned, the surgeon depresses the foot switch to initiate Aquablation therapy. The yellow line on the screen signals the location and progress of the Robot enabling surgeon to actively monitor the treatment in real time. At any point during the treatment, the surgeon can pause Aquablation by lifting his or her foot off the pedal. The AquaBeam® Robotic System aspirates the fluid and tissue during Aquablation to help control fluid balance as well as collect tissue in real time.
Handpiece Removal
Upon completion of Aquablation therapy, the scope is advanced all the way forward within the handpiece and then the handpiece is detached from the articulating arm and removed from the patient.
Clot Evacuation and Catheter Placement
The ultrasound probe is left in place as the surgeon removes clots using an Ellik evacuator, a Toomey syringe, or similar device. Once clots are removed, a Foley catheter can be inserted under ultrasound guidance to ensure proper placement. Then the catheter tensioning device (17.2×) by Procept BioRobotics is placed on the patient and holds the catheter at a specific tension set by the surgeon, and continuous bladder irrigation is used to help prevent the formation of new clots. Like any TUR procedure, if vigorous bleeding continues despite irrigation and traction, arterial bleeding may be the cause, and appropriate management including site-specific figuration of the arterial bleeding may be indicated. This significant arterial bleeding is usually found at the bladder neck. Prior to leaving the operating room, the resectoscope should be reintroduced, and the prostatic fossa and bladder neck should be inspected for arterial bleeding.
Finally, the rectal ultrasound probe is removed from the patient, ending the procedure.
Postoperative Care
Immediately post-Aquablation, the patient is brought to the recovery room; postoperative management is similar to TURP procedures in general. The patients are monitored until anesthesia has worn off. Electrolyte abnormalities are uncommon. Since the resection portion of the procedure is often accomplished in less than 15 minutes, bleeding requiring transfusion is unlikely since traction/catheter balloon management for hemostasis is employed immediately.
Traction is usually released by 12–24 h post operation, and continuous bladder irrigation is slowly weaned off over the next 12–24 h. If the effluent is clear after irrigation is off for 3–5 h, the catheter can be discontinued. Patients are usually given a trial of voiding on postoperative day number one, and if they void, they are discharged.
Results
Since the first study of the Aquablation technique completed by Faber et al. in canine models that demonstrated adequate resection potential with intact, healthy epithelium on histology and preservation of capsule and other underlying structures as well as short operative time, avoidance of thermal energy application, and finely tuned, computerized control as advantages of the therapy, the therapy has quickly advanced to clinical applications with several published clinical studies demonstrating efficacy and safety [24].
Gilling et al. published a first-in-man, single-center study of safety and feasibility in 15 patients with BPH/LUTS refractory to medical therapy [5]. All patients reported a preoperative IPSS of >12, Qmax ≤12 mL/s, Schaffer scale of ≥2, and prostate size of 25–80 mL. Independent review of adverse events produced an acceptable safety profile; all procedures were performed under general anesthesia and found to have succeeded from a technical standpoint, lacking serious or unexpected complication including blood loss and electrolyte imbalance. Eight of 15 patients experienced at least one of the following mild AEs common in MIT procedures within the 30-day postoperative window (Clavien-Dindo grade 1–11): dysuria (3/15), hematuria (3/15), pelvic discomfort (3/15), need for recatheterization (5/15), postoperative cardiac arrhythmia (1/15), and bladder spasms (1/15). No urinary incontinence, erectile dysfunction, or retrograde ejaculation were reported in any case based on International Index of Erectile Function (IIEF) and Incontinence Severity Index (ISI) questionnaires. One patient did require a second procedure within 90 days due to a particularly conservative approach at first operation [8].
At the study’s 6-month follow-up, mean IPPS score improved to 8.6 from a baseline of 23.1 (P < 0.001), while Qmax improved to 18.6 mL/s from 8.6 (P < 0.001). Mean detrusor pressure at Qmax was also measured, averaging 66 cmH2O at baseline and decreasing to 45 cmH2O at follow-up (P < 0.05). Mean prostate size assessed by TRUS was reduced by 31% to 36 mL (P < 0.001). These promising results lead to further development and studies due to the promising functional results in the first-in-man study and the possibility that automated prostate ablation technology could “significantly alter clinical practice.”
The results of a larger multicenter trial of 57 patients, again executed by Gilling and colleagues, mirrored those above. Similar inclusion criteria were maintained though patients with prostate volume of up to 100 mL were treated. However, clinical and safety assessment was continued up to 1 year following surgery (in 33 subjects as of the most recent reporting). All procedures were technically successful without major complication and mean operative and resection times were 38 and 7 minutes, respectively. Mild perioperative adverse events were temporary and occurred at rates similar to those reported for more traditional therapies for BPH [25].
Again, no cases of retrograde ejaculation, urinary incontinence, or erectile dysfunction were recorded. In a comparison between values at baseline and most recent follow-up, IPSS decreased from 22.9 to 6.8, QoL from 5.0 to 1.6, and PVR from 105 to 57 mL; Qmax improved from 7.8 to 16.7 mL/s at 12 months. Investigators found Aquablation to be a feasible, safe, and increasingly efficient modality of minimally invasive surgical intervention for LUTS associated with BPH, remarking that further study in randomized controlled trials was warranted [25].
This led to the WATER Study, a prospective, multicenter, international double-blind randomized clinical trial. Men with LUTS due to BPH with a prostate size of 30–80 cc and a baseline IPSS score of at least 12 points were studied and randomized 2:1 to Aquablation with AquaBeam® Robotic System or standard TURP. One hundred and eighty-one subjects were enrolled, randomized, and treated, 116 to Aquablation and 65 to TURP. Baseline IPSS was 22 and baseline Qmax was 9 cc/sec. Mean prostate size was approximately 53 cc. Performed primarily with general anesthesia (94%) and some with spinal anesthesia (6%), procedure times were similar across groups, 33 (Aquablation) vs. 36 (TURP) minutes, p = 0.2752). Resection time was lower in Aquablation (mean 4 vs. 27 minutes, p < 0.0001). Hospital length of stay was similar at 1.4 days per group (p = NS) [26, 27].
In this study, the primary safety endpoint (Clavien-Dindo grade 1 persistent or grade 2 or higher event in the first 3 months) occurred in 29 Aquablation subjects (25.0%) and 26 TURP subjects (40.0%). The rate difference (Aquablation – TURP) was −15.0%, with a 95% CI of −29.2 to −1.0%. The upper confidence limits were less than the zero, therefore demonstrating statistical superiority of Aquablation vs. TURP. The proportion of men with a worsening of sexual function (decrease in MSHQ score of at least 2 points or decrease in IIEF-5 score of at least 6 points by 6 months) was 32.9% in the Aquablation group vs 52.8% in the TURP group. The proportion of men who experienced persistent anejaculation that were sexually active (Clavien-Dindo grade 1 persistent) in the first 3 months occurred in 8 Aquablation subjects (10%) and 16 TURP subjects (36%). By month 6, 8 (10%) Aquablation and 17 (38%) TURP subjects experienced anejaculation. Finally, the major adverse urologic event in the Aquablation group was noninferior to that of TURP [26, 27].
Mean (SD) IPSS reduction at 12 months was 15.1 (7.0) in the Aquablation group and 15.1 (8.3) in the TURP group (p = 0.9898 for difference). The mean percent reduction in IPSS score was 67% in both groups at 93% and 86.7%, respectively, had improvements of at least 5 points from baseline. Repeated measures analysis showed no statistically significant difference in postoperative change scores across groups nor any statistical interaction between time and treatment. Mean IPSS quality of life score improvement was also similar in both groups (3.2 (1.7) vs. 3.5 (1.6), p = 0.3179) [26, 27].
In both groups, mean maximum urinary flow rates increased markedly postoperatively with mean improvements of 10.3 (11) cc/sec for Aquablation vs. 10.6 (11) cc/sec for TURP (p = 0.8632). The mean 12-month reduction in postvoid residual was 52 (79) and 63 (97) cc (p = 0.4625). In patients with an elevated (>100 cc) postvoid residual, mean reductions in postvoid residual were 107 and 114 cc, respectively. At 1 year, PSA was reduced significantly (p < 0.01) in both groups by 1 point; the reduction was similar across groups (p = 0.9125) [26, 27].
By month 3, fewer men in the Aquablation group had a persistent Clavien-Dindo grade 1 or grade 2 or higher adverse event compared to TURP (primary safety endpoint, 26% vs. 42%, p = 0.0149). Between month 3 and month 12, 40 urologic adverse events occurred. Of these, 8 and 12 were deemed probably or related to the index procedure, but the proportion of subjects with these events was similar across treatment groups. One TURP subject (1.5%) and three Aquablation subjects (2.6%) underwent surgical retreatment for BPH within 1 year from the study procedure (p = NS) [26, 27].
This study demonstrated that Aquablation for LUTS due to BPH provides sustained (12 months) symptom reduction efficacy with a low rate of late adverse events in men with prostates between 30 and 80 cc. Additionally, Aquablation may be a good alternative for men who wish to maintain their ejaculatory function [1].
The large multicenter study also inferred that larger prostates could be safety and effectively treated and lead to a WATER II prospective single-arm clinical trial of Aquablation therapy using the AquaBeam® Robotic System in larger prostates (80–150 cc) [1, 28].
The WATER II study is a prospective, multicenter, international clinical trial of Aquablation for the treatment of LUTS due to BPH in men 45–80 years of age with a prostate volume between 80 and 150 cc as measured by preoperative transrectal ultrasound. In this study and after treatment, study subjects were followed at in-clinic study visits at 1, 3, 6, and 12 months. The study’s primary endpoints were calculated at 3 months [28].
One hundred and one subjects were enrolled and treated from 16 centers. Baseline IPSS was 23 and baseline Qmax was 9 cc/sec, indicative of moderate-to-severe BPH. Mean prostate size was approximately 107 cc.
The procedure was done primarily with spinal anesthesia (82%) with the remainder under general anesthesia (18%). Mean operative time (handpiece placement to urinary catheter placement) was 37 minutes and mean Aquablation resection time was 7.8 min. A Foley catheter single balloon placed in the bladder under mild tension was used for hemostasis in 98 (97.0%) cases. Bladder traction was maintained for an average of 18 hours. A prostatic balloon for direct tamponade was used in three cases for an average duration of 15 hours. No subject underwent post-Aquablation cautery for hemostasis. 59% of subjects were discharged within 1 day and mean length of stay was 1.6 days. Two patients went home the same day of surgery. Most patients (68%) were discharged home with a catheter; the catheter was removed on average 4 days post-Aquablation. Hemoglobin levels decreased from a mean of 14.8 at baseline to 11.9 prior to discharge (drop of 2.9 g/dL, p < 0.0001). Utilization rates for postoperative medications were: pain management (74%), bladder spasm (23%), and antihypertensive (3%) [1, 26–28].
The primary safety endpoint, defined as Clavien-Dindo Grade 2 or higher or any Grade 1 event resulting in persistent disability (e.g., ejaculatory disorder, erectile dysfunction, or permanent incontinence), at 3 months occurred in 45.5% of men, which met the study design goal of less than 65% (p < 0.0001). Ejaculatory dysfunction occurred in 19% of sexually active men. There were no erectile dysfunction events. There were no bleeding events reported beyond the 1-month report. Additionally, no repeat procedures for tissue removal were required as of the 3-month visits [1, 28].
The MSHQ-EjD change score was −2 ± 5.1 at 3 months, which met the prespecified endpoint (p = 0.0026) and thus preserved ejaculatory function in the study group. The IIEF-5 change score was 0.1 ± 6.4 at 3 months which met the prespecified endpoint (p < 0.0001) and thus preserved erectile function in the study group [1, 28].
Mean (SD) IPSS improved from 23.2 (6.3) at baseline to 6.7 (5.1) at 3 months (a 16.5-point improvement) which met the study’s primary efficacy endpoint goal (p < 0.0001). IPSS QOL decreased from 4.6 at baseline to 1.8 at 3 months (p < 0.0001). Maximum urinary flow rate increased from 8.7 to 20.1 cc/sec (an improvement of 11.1 cc/sec, p < 0.0001) and postvoid residual decreased from 131 at baseline to 57 at 3 months (a 79 cc decrease, p < 0.0001) [1, 28]. Transrectal ultrasound, performed preoperatively and at 3 months, showed a prostate volume change from 107 ± 20 cc to 63 ± 26, a 42% reduction [1, 28]. There were 16 subjects entering the trial that utilized a urinary catheter within 45 days of treatment. At the 3-month visits, none of these patients required the use of a urinary catheter [1, 28].
In summary, current studies demonstrated that Aquablation for LUTS due to BPH provides sustained (12 months) symptom reduction efficacy with a low rate of late adverse events in men with prostates between 30 and 150 cc and is a viable robotic alternative to the standard TURP [1, 26–28].
Conclusion
While more long-term studies on the efficacy of biTURP and Aquablation are necessary, it appears that biTURP and Aquablation provide a reasonable, efficacious, and safer alternative for transurethral resection of the prostate when compared to traditional modalities.
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