Water ablation’s safety, efficiency in BPH assessed

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An image-guided technique for treating LUTS associated with BPH is reproducible and promising, researchers say.

Minimally invasive water jet therapy (Aquablation) for the targeted removal of prostate tissue was safe and feasible in follow-up to 12 months in a multicenter clinical trial of men with lower urinary tract symptoms secondary to BPH.

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In 57 men with a mean prostate size of 48 mL, no significant intraoperative complications occurred with image-guided water jet therapy, and procedural success was 100%, said first Peter Gilling, MD, at the AUA annual meeting in San Diego.

The results “suggest that it’s a promising new technology,” he said. “Compared to freehand techniques, there’s no real technical difficulty because it’s all done in the set-up, and the procedure is much more reproducible. It’s almost urologist-free. In fact, some of the best procedures… have been done by the engineers.”

The Aquablation System (PROCEPT BioRobotics) combines image guidance and robotics for targeted removal of prostate tissue. A high-velocity saline stream (AquaBeam) is generated using water jets driven by a high-pressure pump. The stream creates a cavity in prostatic glandular tissue without the production of heat. The flow rate generated by the pump (up to 10,000 PSI) dictates the depth of the stream’s penetration.

The procedure is performed using real-time transrectal ultrasound image guidance, which allows conformal planning of the target region of the prostate to be treated. The target tissue contour and depth are programmed into the system by the surgeon.

To obtain hemostasis, a low-power blue laser beam is captured in a low-pressure water column to perform surface coagulation of the fossa.

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The 57 patients in the study were treated at four sites. The mean prostate size treated was 48 mL, with a maximum of 102 mL. About half (46%) of the men had a median lobe.

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The procedure time overall averaged 45 minutes, but the Aquablation time was only 7 minutes. “The combination of surgical mapping, high-velocity saline with the robotic guidance means that the actual ablation time is very short,” said Dr. Gilling, of Tauranga Hospital, Tauranga, New Zealand.

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No patient had to be converted to another procedure. Over 12 months, the mean prostate volume reduction was 37%. The mean catheter withdrawal time was 1.2 days.

Mean hospital time was 1.8 days. Two reoperations were required and the recatheterization rate was 12%. There were no significant intraoperative complications, no bleeding complications, and no clot retention. No blood transfusions were required. Postoperative dysuria was minimal, and adverse events were typically mild and transient.

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The mean International Prostate Symptom Score declined from 23.2 preoperatively to 5.7 by 13 weeks, and remained at 6.0 or less throughout the rest of the 12-month follow-up. The mean Qmax increased predictably from 7.9 mL/sec at baseline to 16.8 mL at 13 weeks, “which is as much as you would see with a TURP with a cavity of this size,” he said.

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The mean quality of life score improved from 4.5 at baseline to 1.2 at 13 weeks, and improved further to 1.1 by week 52. The mean postvoid residual declined from 98 mL preoperatively to 48 mL by 4 weeks, and was 52 mL at week 52.

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No cases of urinary incontinence or erectile dysfunction were reported.

A randomized study called WATER (Water Ablation Therapy for Endoscopic Resection of Prostate Tissue) will provide definitive clinical data to evaluate the efficacy of water ablation.

The study was funded by PROCEPT BioRobotics. Dr. Gilling serves as an investigator and meeting participant/lecturer for the company.