Benign prostatic hyperplasia (BPH) is a common condition among aging men, often leading to lower urinary tract symptoms (LUTS) that significantly impact quality of life. Water vapor thermal therapy (Rezum) is a minimally invasive surgical treatment known to improve symptoms in patients with BPH. While its efficacy in reducing the International Prostate Symptom Score (IPSS) and enhancing urinary flow has been well established, its impact on overactive bladder (OAB) symptoms remains controversial. Some studies report improvements in the Overactive Bladder Symptom Score (OABSS) following Rezum therapy, while others show no substantial changes. Given these mixed findings, our primary aim was to assess whether Rezum therapy improves both OABSS and IPSS, along with other urodynamic parameters. As a retrospective analysis, we also sought to evaluate the overall efficacy and safety of Rezum therapy in a real-world clinical setting, examining whether increasing the number of water vapor injections enhances treatment outcomes.

This was a retrospective, single-institution study conducted in Japan. A total of 102 patients underwent Rezum procedures between July 2023 and July 2024. Patients were divided into two groups:

・Spontaneous Voiding Group (n=61): Patients able to urinate spontaneously.
・Non-Spontaneous Voiding Group (n=41): Patients requiring intermittent self-catheterization (n=26) or with an indwelling urethral catheter (n=15).

We evaluated the following parameters preoperatively and at three months postoperatively:
・Symptom scores: IPSS and OABSS
・Quality of life: IPSS-QOL
・Uroflowmetry: peak urinary flow rate (Qmax) and post-void residual volume (PVR)
・Prostate volume (PVol): assessed using MRI

Additionally, we assessed whether increasing the number of water vapor injections correlated with improved treatment outcomes.

On average, 8.9 water vapor injections were administered per procedure, resulting in a significant reduction in prostate volume (PVol) by 29.2% (from 65.36 mL to 46.27 mL), confirmed by MRI.

In the Spontaneous Voiding Group (61 patients), the IPSS decreased by 65.1% (from 21.8 to 7.6), and the quality of life score (IPSS-QOL) improved by 70.0% (from 5.3 to 1.6). The peak urinary flow rate (Qmax) increased by 39.8% (from 9.81 to 13.71 mL/s), and post-void residual (PVR) volume decreased by 47.0% (from 67.8 to 35.9 mL). Additionally, the total OABSS score decreased by 26.3% (from 7.0 to 5.1), reflecting significant improvements in overactive bladder symptoms. All changes in these parameters were statistically significant (p < 0.01).

In the Non-Spontaneous Voiding Group (41 catheter-dependent patients), 98% of patients achieved catheter independence, and all patients who had indwelling urethral catheters due to urinary retention were able to have them removed postoperatively.

These findings suggest that Rezum therapy leads to significant improvements in both IPSS and OABSS within three months. The substantial reduction in prostate volume (PVol), as confirmed by MRI, further supports the treatment's efficacy. Furthermore, nearly all catheter-dependent patients achieved catheter independence, highlighting its effectiveness in severe cases. The potential impact of increasing water vapor injections on clinical outcomes remains an area for further investigation.

This retrospective, single-institution study confirms that Rezum water vapor therapy is a safe and effective minimally invasive treatment for BPH. It provides early and significant improvements in LUTS, particularly in IPSS and OABSS, while also promoting catheter independence in patients with urinary retention.