WATER: A Double-Blind, Randomized, Controlled Trial of Aquablation® vs Transurethral Resection of the Prostate in Benign Prostatic Hyperplasia

J Urol. 2018 May;199(5):1252-1261. doi: 10.1016/j.juro.2017.12.065. Epub 2018 Jan 31.


Purpose: We compared the safety and efficacy of Aquablation and transurethral prostate resection for the treatment of lower urinary tract symptoms related to benign prostatic hyperplasia.

Materials and methods: In a double-blind, multicenter, prospective, randomized, controlled trial 181 patients with moderate to severe lower urinary tract symptoms related to benign prostatic hyperplasia underwent transurethral prostate resection or Aquablation. The primary efficacy end point was the reduction in International Prostate Symptom Score at 6 months. The primary safety end point was the development of Clavien-Dindo persistent grade 1, or 2 or higher operative complications.

Results: Mean total operative time was similar for Aquablation and transurethral prostate resection (33 vs 36 minutes, p = 0.2752) but resection time was lower for Aquablation (4 vs 27 minutes, p <0.0001). At month 6 patients treated with Aquablation and transurethral prostate resection experienced large I-PSS improvements. The prespecified study noninferiority hypothesis was satisfied (p <0.0001). Of the patients who underwent Aquablation and transurethral prostate resection 26% and 42%, respectively, experienced a primary safety end point, which met the study primary noninferiority safety hypothesis and subsequently demonstrated superiority (p = 0.0149). Among sexually active men the rate of anejaculation was lower in those treated with Aquablation (10% vs 36%, p = 0.0003).

Conclusions: Surgical prostate resection using Aquablation showed noninferior symptom relief compared to transurethral prostate resection but with a lower risk of sexual dysfunction. Larger prostates (50 to 80 ml) demonstrated a more pronounced superior safety and efficacy benefit. Longer term followup would help assess the clinical value of Aquablation.

Keywords: lower urinary tract symptoms; prostatic hyperplasia; robotic surgical procedures; transurethral resection of prostate; water.

Publication types

  • Comparative Study
  • Multicenter Study
  • Pragmatic Clinical Trial
  • Randomized Controlled Trial

MeSH terms

  • Ablation Techniques / adverse effects
  • Ablation Techniques / methods*
  • Aged
  • Double-Blind Method
  • Ejaculation / physiology
  • Electrocoagulation / adverse effects
  • Electrocoagulation / methods*
  • Humans
  • Male
  • Middle Aged
  • Postoperative Complications / epidemiology
  • Postoperative Complications / etiology
  • Postoperative Complications / physiopathology
  • Prospective Studies
  • Prostate / surgery
  • Prostatic Hyperplasia / diagnosis
  • Prostatic Hyperplasia / surgery*
  • Robotic Surgical Procedures / adverse effects
  • Robotic Surgical Procedures / methods*
  • Severity of Illness Index
  • Sexual Dysfunction, Physiological / epidemiology
  • Sexual Dysfunction, Physiological / etiology
  • Sexual Dysfunction, Physiological / physiopathology
  • Transurethral Resection of Prostate / adverse effects
  • Transurethral Resection of Prostate / methods*
  • Treatment Outcome
  • Water


  • Water