Category: BPH/LUTS: Electrosurgery, Lasers & Other Technology

MP6-5 - The WATER Study Clinical Results – Aquablation vs. TURP for Moderate-to-Severe LUTS in men with BPH: Urodynamics and 1 year results

Fri, Sep 21
10:00 AM - 12:00 PM

Introduction & Objective :

Early reports of Aquablation (robotic, high-velocity waterjet prostate resection) for lower urinary tract symptoms due to benign prostatic hyperplasia suggested efficacy similar to that of TURP.  We aimed to compare the safety and efficacy of prostate ablation using Aquablation (A) vs TURP (T). 


Methods :

In this randomized, blinded, multi-center phase III trial, men with moderate-to-severe LUTS related to BPH were assigned to TURP or Aquablation. The trial had a co-primary safety and efficacy endpoint designed to show non-inferiority regarding efficacy. The primary safety endpoint was the occurrence of persistent CD Grade 1 or Grade 2 or higher operative complications at 3 months. The primary efficacy endpoint was the reduction in IPSS score at 6 months. The 12 month data and the urodynamics sub-study results are presented.


Results :

The mean baseline IPSS score, demographic profile, and mean prostate volume (T: 52 mL vs. A: 54 mL, p=0.31) were similar in both arms. Mean operative time was equivalent between the two groups (T: 35.5 vs. A: 32.8 minutes, p=0.28), but mean ‘resection’ time was significantly lower in the Aquablation group (27 vs. 4 minutes, p


The primary safety endpoint occurred in 26% of Aquablation subjects and 42% of TURP subjects demonstrating superiority of Aquablation versus TURP. The difference in primary endpoint safety rate was driven mainly by retrograde ejaculation. Persistent retrograde ejaculation in the first 6 months occurred in 10% of Aquablation subjects and 38% of TURP subjects. 


Mean IPSS scores decreased from 22.9 at baseline to 5.9 and 22.2 to 6.8 in the Aquablation and TURP groups, respectively. The IPSS change score at month 6 was 1.8 points larger after Aquablation demonstrating non-inferiority.


Urodynamics studies were performed in 64 of the subjects at baseline and again at 6 months. At 6-month follow-up, pdet@Qmax decreased by 36 and 37 cm H20 respectively (p<.0001 compared to baseline for both arms) with no significant difference in decrease between groups (p=.8919). The number of men urodynamically obstructed decreased from 75% to 22% in Aquablation and 100% to 23% in the TURP group.


Conclusions :

In patients with moderate-to-severe LUTS due to BPH, surgical prostate ablation using a robotically guided waterjet showed similar symptom relief compared to TURP but with a lower risk of retrograde ejaculation. Urodynamic relief of obstruction was similar.

Peter Gilling

Head of Bay of Plenty Clinical Campus
University of Auckland, Tauanga
Tauranga, Bay of Plenty, New Zealand

Claus Roehrborn

UT Southwestern Medical Center
Dallas, Texas