Using a high-pressure water jet to operate on an enlarged prostate can better preserve the ability to ejaculate, compared with standard laser surgery, finds research.
The technique has similar outcomes to laser surgery and can be performed with robot assistance, so could reduce waiting times for men with urinary problems caused by an enlarged prostate.
Initial findings of the WATER III trial are presented today [Saturday 22 March] at the 2025 European Association of Urology (EAU) Congress in Madrid.
The WATER III trial involved a water-based surgical procedure, called Aquablation, currently used for small- and medium-sized prostates. The trial assessed its safety and effectiveness for use with large prostates, compared with surgery using lasers. It also investigated adverse side effects such as erectile dysfunction and urinary incontinence.
The trial was led by researchers from the University of Bonn and involved patients across Germany and the UK.
An enlarged prostate, known as Benign Prostatic Hyperplasia (BPH), is the most common prostate condition in older men. The prevalence of BPH increases with age, affecting over 50% of men aged over 50 and rising to more than 80% in those aged over 70, with global and regional variations influenced by population aging and prostate volume differences. While non-cancerous, it can cause urinary problems and significantly impact men's health.
As the prostate gland grows, BPH can squeeze the urethra leading to a frequent need to urinate, a weak urine stream, and leaking or dribbling of urine. Where lifestyle changes or medication are not effective, men can opt for surgery. Most commonly, this involves using a wire loop or laser to break up and remove the excess prostate tissue to open up the urethra.
Retrograde ejaculation is a common side effect of BPH surgery. This is where semen is ejaculated into the bladder, rather than through the penis. While not a health risk, retrograde ejaculation can compromise sexual enjoyment and fertility.
Aquablation is a minimally invasive surgical procedure that uses a high-pressure water jet, under robotic guidance and ultrasound imaging, to locate and destroy excess prostate tissue. Standard laser surgery for BPH includes Holmium laser prostate surgery (HoLEP) and Thulium laser enucleation of the prostate (ThuLEP), which break up or vaporise excess prostate tissue.
In the trial, the researchers recruited 202 men who required surgery for their BPH. The men all had large prostates (between 80 – 180 mL). Just over half (98) of patients were assigned to undergo aquablation therapy, with the remainder (88) assigned to undergo either HoLEP or ThuLEP laser surgery.
During a three-month follow-up, men were assessed for retrograde ejaculation, incontinence and the severity of their lower urinary tract symptoms, using the International Prostate Symptom Score.
Of the 89 men in the trial who were sexually active, retrograde ejaculation was experienced by just 15% of men in the aquablation group compared with over three-quarters of men (77%) in the laser surgery group. Urinary incontinence was reported in 9% of the men in the aquablation group compared with 20% in the standard treatment group. Short-term symptom improvement and adverse events were similar across both groups.
Lead researcher, Professor Manuel Ritter, Head of Urology at the University Hospital Bonn, Germany, said: "Our study shows significant promise for aquablation therapy as an alternative to laser-based treatments for men with larger prostates with BPH. Many men accept their symptoms as a normal part of ageing, but after surgery, these patients are very happy to get rid of their medication and symptoms. Evidence that it is also effective at preserving ejaculatory function brings added benefits for those who wish to preserve their sex lives."
He continues: "The learning curve for surgeons to perform laser surgery is steep, so the ability to offer aquablation to men even with larger prostates will make treatments more accessible."
There are several surgical approaches for BPH. The most common option, transurethral resection of the prostate (TURP), uses a heated wire loop to shave away excess prostate tissue. A previous five-year trial has shown aquablation can significantly reduce the risk of retrograde ejaculation as a side effect compared with TURP.
Commenting on the trial, Professor Cosimo De Nunzio, Associate Professor of Urology at Sapienza University of Rome, Italy, and Member of the EAU Scientific Congress Office, said:
"Abnormal ejaculation is a very frequent complication following BPH surgery, and so the challenge we have is to strike a balance between treating the symptoms and preserving ejaculation function. Retrograde ejaculation is a particular concern for men who would prefer to see little to no impact on their sex lives following treatment. So, for this group of men, the results of this study show that aquablation is a very promising option.
"However, the follow-up period of three months is very short and future research would need to include patients with chronic urinary retention or urethral catheters, who often require treatment for BPH. Longer-term studies would also need to include other important measures, like a reduction in prostate-specific antigen in the blood, or an improved urine flow rate."
The trial was funded by aquablation therapy developer PROCEPT BioRobotics ® and the sponsor is the University of Bonn.
