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Waterjet Ablation Therapy for Endoscopic Resection of prostate tissue trial (WATER) vs WATER II: comparing Aquablation therapy for benign prostatic hyperplasia in 30-80 and 80-150 mL prostates

  • David-Dan Nguyen 1,
  • Neil Barber 2,
  • Mo Bidair 3,
  • Peter Gilling 4,
  • Paul Anderson 5,
  • Kevin C. Zorn 6,
  • Gopal Badlani 7,
  • Mitch Humphreys 8,
  • Steven Kaplan 9,
  • Ronald Kaufman 10,
  • Alan So 11,
  • Ryan Paterson 11,
  • Larry Goldenberg 11,
  • Dean Elterman 15,
  • Mihir Desai 12,
  • Jim Lingeman 13,
  • Claus Roehrborn 14,
  • Naeem Bhojani 6
1 Faculty of Medicine, McGill University, Montreal, QC, Canada 2 Frimley Park Hospital, Urology, Frimley, Surrey, UK 3 San Diego Clinical Trials, San Diego, CA, USA 4 Bay of Plenty District Health Board Clinical School, Urology, Tauranga, New Zealand 5 Royal Melbourne Hospital, Urology, Melbourne, Victoria, Australia 6 Centre Hospitalier de l’Universite de Montreal, Division of Urology, Montreal, QC, Canada 7 Wake Forest School of Medicine, Urology, Winston-Salem, NC, USA 8 Mayo Clinic, Department of Urology, Phoenix, AZ, USA 9 Department of Urology, Mount Sinai Hospital, New York, NY, USA 10 Division of Urology, Albany Medical College, Albany, NY, USA 11 University of British Columbia, Urologic Sciences, Vancouver, BC, Canada 12 USC Institute of Urology, University of Southern California, Urology, Los Angeles, CA, USA 13 Institute for Kidney Stone Disease, Methodist Hospital, Indianapolis, IN, USA 14 UT Southwestern Medical Centre, Urology, Dallas, TX, USA 15 Division of Urology, University of Toronto, Montreal, QC, Canada

Publication: BJU International, October 2019


To compare the outcomes of Aquablation in 30–80 mL prostates with those in 80–150 mL prostates. Surgical options, especially with short learning curves, are limited when treating large prostates for lower urinary tract symptoms (LUTS) due to benign prostatic hyperplasia (BPH). Aquablation (AquaBeam System, PROCEPT BioRobotics Inc., Redwood City, CA, USA) could solve this issue with global reproducibility, independent of prostate volume.

Patients and Methods

Waterjet Ablation Therapy for Endoscopic Resection of prostate tissue (WATER [W‐I]; NCT02505919) is a prospective, double‐blind, multicentre, international clinical trial comparing Aquablation and transurethral resection of the prostate (TURP) for the treatment of LUTS/BPH in prostates between 30 and 80 mL. WATER II (W‐II; NCT03123250) is a prospective, multicentre, single‐arm international clinical trial of Aquablation in prostates between 80 and 150 mL. We compare baseline parameters and 12‐month outcomes in 116 W‐I and 101 W‐II study patients. Students’ t‐test or Wilcoxon tests were used for continuous variables and Fisher’s test for binary variables.


The mean (SD) operative time was 33 (17) and 37 (13) min in W‐I and W‐II, respectively. Actual treatment time was 4 and 8 min in W‐I and W‐II, respectively. The mean change in the International Prostate Symptom Score was substantial averaging (at 12 months) 15.1 in W‐I and 17.1 in W‐II (P = 0.605). By 3 months, Clavien–Dindo grade ≥II events occurred in 19.8% of W‐I patients and 34.7% of W‐II patients (P = 0.468).


Aquablation clinically normalises outcomes between patients with 30–80 mL prostates and patients with 80–150 mL prostates treated for LUTS/BPH, with an expected increase in the risk of complications in larger prostates. Long‐term outcomes of procedure durability are needed.