The Technology

How Does Rezūm
Water Vapor Therapy Work?

Rezūm harnesses one of nature's most powerful thermodynamic phenomena: the latent heat released by water vapor condensing into liquid inside prostate tissue.

In just 10 minutes of outpatient treatment, water vapor at 103°C is delivered into the obstructive tissue via a transurethral cystoscope. Cell death occurs within the prostate, and the body naturally reabsorbs the destroyed tissue over the following weeks.

Rezūm Water Vapor Therapy system – the device

Mechanism

Step-by-Step Thermodynamics

Phase 1

Saline Generation

A small amount of sterile saline is heated to produce water vapor (steam) at 103°C inside the device.

Phase 2

Transurethral Access

A fine cystoscope is introduced transurethrally. No incision, no external surgical access.

Phase 3

Targeted Injection

9-second steam pulses are injected into the stromal tissue (transition zone) compressing the urethra.

Phase 4

Condensation Energy

On contact with cooler tissue, the vapor condenses and releases 540 cal/g of energy — destroying cells while preserving the fibromuscular capsule.

Phase 5

Controlled Cell Death

Precise, contained necrosis of obstructive cells. No damage to nerves, surrounding tissues, or seed the urethral mucosa.

Phase 6

Natural Reabsorption

Over 2 to 6 weeks, the immune system reabsorbs the destroyed tissue, opening the urethral lumen progressively.

Anatomical Safety

Why Sexual Function Is Preserved

The fundamental principle of Rezūm lies in treating the target tissue (transition zone) while respecting the surrounding anatomical structures that control sexual function.

Fibromuscular capsule limits thermal diffusion beyond the prostate
Ejaculatory ducts preserved (no iatrogenic retrograde ejaculation)
External urethral sphincter intact (no urinary incontinence)
Neurovascular bundles (NVB) not exposed to heat
Urethral mucosa spared by targeted injection into the stroma

Unlike TURP where electric resection touches the ejaculatory ducts, Rezūm vapor remains confined within the prostate stroma.

Clinical Evidence

Published Clinical Results

Results from the pivotal trials and long-term follow-up studies.

−50%

Reduction in I-PSS score at 3 months — average symptom improvement

−73%

Reduction in Qmax urine flow obstruction index

<5%

Overall retreatment rate at 5 years

7 yrs

Maximum clinical follow-up with consistent data

94%

Patient satisfaction at 12 months post-procedure

100%

Erectile and ejaculatory function preservation in clinical trials

Ideal Indications

Moderate to severe BPH (I-PSS ≥ 8)
Prostate volume 30–80 cc
Median lobe hyperplasia present
Sexual function preservation priority
Desire to avoid major surgery
Patient aged 50+ who is active
Failure or intolerance of medical treatment

Relative Contraindications

Prostate volume > 120 cc (discuss with physician)
Active urinary tract infection
Urethral stricture
Active prostate or bladder cancer
Implanted electronic device near prostate (pacemaker)
Previous prostate surgery in the same area

How Does RezūmWater Vapor Therapy Work?