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Transurethral water vapor ablation of the prostate with the Rezūm system: Urodynamic findings

  • Evangelista Martinelli,
  • Luca Cindolo,
  • Francesco Saverio Grossi,
  • Markus Antonius Kuczyk,
  • Giampaolo Siena,
  • Matthias Oelke


The efficacy of the transurethral convective interstitial radiofrequency water vapor thermal ablation of the prostate with the Rezūm system for the treatment of male lower urinary tract symptom due to benign prostatic hyperplasia is well proven.

The improvement of urodynamic parameters obtained from a simple uroflowmetry cannot measure the effect of water vapor injection on the bladder outlet obstruction.


This monocentric retrospective pilot study analyzes the data of pressure-flow studies performed before and after 17 Rezūm procedures to answer the question whether thus obtained ablation of prostate tissue has a disobstructive effect on the bladder outlet.


All the functional outcomes were consistently improved after the procedure, with a median flowrate increase of 5.1 ml/s (p = 0.0022) and a median postvoid residual urine (PVR) reduction of 100 ml (p = 0.0042). The prostate volume was reduced by 40% (p < 0.0001) and the median Bladder Outlet Obstruction Index (BOOI) reduction was 53.8 (p < 0.0001).


These data show that the possibility to significantly reduce the obstruction grade with even a single Rezūm procedure is concrete and seems to be independent from the degree of the obstruction grade.

Mr. Sachin Malde

This study aims to answer an important but understudied question regarding the outcome of Rezūm treatment for lower urinary tract symptoms (LUTS) due to benign prostatic enlargement: does Rezum treatment lead to the resolution of urodynamically-proven benign prostatic obstruction?

The study comprises a series of 17 patients who underwent urodynamic investigation before and after Rezum treatment. Prior to treatment, the patients had a mean bladder outlet obstruction index (BOOI) of 64.7cmH2O (obstructed > 40), and after treatment the mean BOOI fell to 15.1cmH2O (unobstructed). This was confirmed with other classification methods (Schafer grade and CHESS). Interestingly, one patient who had a good symptomatic outcome had a worsening urodynamic grade of obstruction. These findings could have important clinical implications when considering indications for Rezum treatment.

If there is truly significant urodynamic resolution of obstruction, then Rezum treatment may be beneficial to patients with urinary retention, or to those who have significant secondary storage LUTS in whom urodynamic disobstruction is likely required to improve the likelihood of resolution of storage LUTS.

The limitations of the series should be acknowledged: it is retrospective, small, and prone to selection bias. All patients had a good symptomatic outcome, but it would be important to compare these findings to a group that did not have a successful outcome. Furthermore, assessing the effect on urodynamic filling phase parameters would be important as well. However, the study is notable for providing evidence in an area where very little evidence exists, and highlights the need for further studies to ascertain the urodynamic outcomes of this treatment so that patient selection for treatment and patient counselling can be optimised.