Evidence Notes · No. 06
← All notesA drug-coated balloon that opens a scarred urethra and tries to stop it closing again. Genuinely better than repeat dilatation for the right stricture — and not a substitute for reconstruction.
A urethral stricture is a narrowing caused by scar tissue inside the urethra—the tube that carries urine from the bladder out of the body. It can cause a weak or spraying stream, straining, incomplete emptying, urinary infections and, occasionally, complete urinary retention.
Traditional keyhole treatments can open the narrowing, but recurrent strictures often close again. Optilume aims to improve on ordinary dilatation by combining a balloon with a drug intended to reduce renewed scar formation.
The evidence is encouraging, but it applies most clearly to a particular group: adult men with a short, recurrent stricture in the bulbar or anterior urethra who have already undergone endoscopic treatment. It should not be presented as a universal replacement for urethroplasty—the open reconstructive operation that remains the most established definitive treatment for many recurrent or complex strictures.
This article examines what Optilume is, how well it works, its risks, and where the evidence remains uncertain.
Read this first
Important distinction: this article concerns the Optilume Urethral Drug-Coated Balloon for urethral strictures. A separate device called Optilume BPH is used for benign prostate enlargement. They should not be treated as the same procedure or evidence base.
| Question | Best available answer |
|---|---|
| Does it outperform ordinary repeat dilatation or internal urethrotomy? | In the ROBUST III randomised trial, the urethra remained anatomically open at six months in 75% after Optilume versus 27% after standard endoscopic treatment.1 |
| How many avoid another procedure? | 77.8% were free from repeat intervention at two years and 71% at three years in the Optilume arm of ROBUST III.2, 3 |
| What is the longest follow-up? | In the separate, single-arm ROBUST I study, estimated freedom from repeat intervention was 71.7% at five years.4 |
| How much can symptoms and flow improve? | In ROBUST I, average IPSS fell from 25.2 to 7.2 and maximum flow rose from 5.0 to 19.9 mL/second at five years.4 |
| What are the common risks? | Burning or pain when urinating, blood in the urine and urinary infection. A meta-analysis estimated an overall complication rate of 9.5%, mostly mild and temporary.5 |
| Who best matches the evidence? | Men with a short recurrent bulbar/anterior stricture, generally no longer than 3 cm, following at least two failed endoscopic treatments.1, 14 |
These figures are study averages, not guarantees for an individual patient. “Success” also varies between studies: it may mean that a camera can pass through the urethra, that symptoms improve, or simply that no further operation has yet been required.
Important precaution
Paclitaxel remains detectable in semen for months — in 60% of tested men at one month, 39% at three months and 8.3% at six. It is the part of this treatment most often left out of the conversation, and the part with consequences for someone else.
Optilume is an endoscopic treatment for male urethral stricture disease. Endoscopic means that instruments are passed through the natural urinary passage rather than through an external surgical cut.
The system uses a small balloon coated with paclitaxel, a drug that limits cell division. Paclitaxel has long been used on drug-coated balloons in blood vessels. In the urethra, it is intended to reduce the overactive healing response that can rebuild scar tissue after the narrowing has been opened.
The balloon is removed at the end of treatment. No permanent implant is left behind.
Optilume does not remove prostate tissue and does not treat an enlarged prostate. A person can have both benign prostate enlargement and a urethral stricture, so identifying the true cause—or causes—of poor flow is important before treatment.
Treatment has two linked effects:
In ROBUST III, the drug-coated balloon was kept inflated for at least five minutes. A urinary catheter was then left in place and removed after two to five days.2 Exact technique, anaesthetic and catheter duration can vary between centres.
The immediate opening comes from dilatation; the drug is intended to make that opening last longer.
For short, recurrent anterior strictures, the answer is yes: Optilume works better than another ordinary endoscopic procedure over the time studied.
The strongest evidence comes from ROBUST III, a multicentre, single-blind randomised controlled trial. It enrolled 127 men with:
Participants had undergone an average of 3.6 previous procedures, and the average stricture was 1.7 cm long. At six months, anatomical success—being open enough to pass a 14 French catheter or 16 French flexible camera—was achieved in:
DVIU means cutting the stricture internally under direct camera vision. This randomised comparison provides reasonably strong evidence that adding the drug-coated balloon improves short-term patency after repeated failure of ordinary endoscopic treatment.
The trial does not prove that Optilume is as durable as urethroplasty, because urethroplasty was not the comparator.
Urethra still open at 6 months
27%→75%standard treatment → Optilume
ROBUST III, 127 men randomised, single-blind. Every man had already failed at least two endoscopic treatments.
What this trial does not show Urethroplasty was not the comparator. The trial establishes that the drug-coated balloon beats another ordinary endoscopic procedure. It says nothing about whether it matches open reconstruction, and it should not be quoted as though it did.
Studies commonly use the International Prostate Symptom Score (IPSS). Despite its name, the questionnaire measures lower urinary tract symptoms and can be used in men with a urethral stricture. Scores range from 0 to 35; a higher score indicates worse symptoms.
The clearest long-term numerical result comes from ROBUST I, a prospective multicentre study of 53 men with recurrent bulbar strictures no longer than 2 cm. At five years, average IPSS had fallen from:
25.2 before treatment to 7.2 after treatment.4
That is a large average change—from severe symptoms to the upper end of the mild range. However, ROBUST I was a single-arm study: everyone received Optilume, and there was no control group. Only 31 of the original 53 participants completed all scheduled follow-up, although the analysis accounted for known failures.
At five years, 58% achieved “functional success”, defined in this study as at least a 50% IPSS improvement without retreatment.4 That figure is lower than the proportion free from another procedure because symptom-based success is a stricter, different outcome.
Maximum urinary flow, or Qmax, is the fastest flow recorded during a urine-flow test.
In ROBUST I, average Qmax increased from:
5.0 mL/second before treatment to 19.9 mL/second at five years.4
Average post-void residual—the urine left in the bladder after urinating—fell from 141.4 mL to 59.5 mL.4
ROBUST III also found clinically meaningful improvements in IPSS, Qmax and residual urine that were maintained through two and three years in the Optilume group.2, 3
A 2024 systematic review and meta-analysis combined seven studies involving 457 patients. It found significant overall improvements in both IPSS and Qmax, with an estimated recurrence-free proportion of 80.83%.5 That pooled percentage should be interpreted cautiously because the studies used different follow-up periods, definitions of recurrence and patient populations. Fixed-time results from ROBUST III and ROBUST I are more useful for discussing what may happen at two, three or five years.
Flow does not depend on the urethra alone. Bladder muscle weakness, prostate enlargement or another obstruction can limit improvement even when the stricture has been successfully opened.
The stricture is physically opened during the procedure, so the mechanical effect is immediate. Many patients notice a stronger stream after the catheter is removed.
The first days or weeks can still involve:
These early healing symptoms do not automatically mean that treatment has failed. Conversely, a good initial stream does not prove that the stricture will remain open; recurrence is usually assessed through symptoms, flow testing and sometimes cystoscopy or imaging over time.
There are now outcome data to five years, but their strength differs by time point.
ROBUST III directly compared Optilume with standard endoscopic treatment. It showed much better anatomical patency at six months and a lower need for reintervention through one year.1
After the blinded comparative phase ended, the control group was not followed beyond one year. At two years, 77.8% of Optilume patients remained free from repeat intervention. The often-quoted comparison with 23.6% in the control group uses the control result at one year, not two years, so it is not a same-time comparison.2
At three years, 71% of the Optilume group remained free from repeat intervention, with symptom and flow improvements maintained.3 These later results are useful but should be described as follow-up of the original treatment arm, not as a continuing three-year randomised comparison.
ROBUST I provides the longest dedicated prospective follow-up. Estimated freedom from repeat intervention was 71.7% at five years.4
This is reassuring, especially in men whose previous endoscopic treatment had failed. But it came from 53 participants with bulbar strictures no longer than 2 cm, without a comparison group. It is not equivalent to a large randomised five-year trial.
The fair conclusion is that Optilume has credible medium-term durability and encouraging five-year evidence in carefully selected men, while its lifetime durability and performance in more complex strictures remain uncertain.
Free from repeat intervention
77.8%at two years
ROBUST III, Optilume arm.
Free from repeat intervention
71%at three years
Same arm. Symptom and flow improvements maintained.
Free from repeat intervention
71.7%at five years
ROBUST I — a different, smaller, single-arm study of 53 men with bulbar strictures under 2 cm.
Two studies, not one curve ROBUST I and ROBUST III enrolled different men under different criteria. Their two-, three- and five-year figures cannot be plotted as a single line, and the widely quoted comparison against 23.6% uses the control group’s one-year result against Optilume’s two-year one.
The most patient-relevant measure is whether another stricture procedure becomes necessary.
These percentages should not be placed on a single continuous curve because ROBUST I and ROBUST III were different studies with different entry criteria and participants.
Retreatment may involve another dilatation, DVIU, a further Optilume procedure or urethroplasty. The safety and benefit of repeatedly treating the same stricture with Optilume have not been extensively studied, and repeated exposure increases the paclitaxel dose.16
Optilume is less invasive than open reconstruction, but it is still a urethral procedure and is not risk-free.
The most frequently reported problems are:
The 2024 meta-analysis estimated a weighted complication rate of 9.5%, with most events mild and temporary.5 In ROBUST III, haematuria and dysuria were more common after the drug-coated balloon than after standard endoscopic treatment—11.4% versus 2.1% when considered together in the European guideline summary—but serious treatment-related complications were uncommon.1, 14
ROBUST I reported no serious treatment-related adverse events through five years.4 Small real-world cohorts have also generally reported low short-term complication rates, but uncommon harm is difficult to measure reliably in small, retrospective studies.7
An active urinary infection should be treated before the procedure. Manufacturer instructions also list hypersensitivity to paclitaxel or related compounds as a contraindication. Some regional instructions list certain urological implants, such as a penile implant or artificial urinary sphincter, as contraindications; local product labelling and individual anatomy must therefore be checked.16
Paclitaxel can be present in semen after treatment. The manufacturer advises men to abstain from sex or use a condom for 30 days to reduce a partner’s exposure. Men with a partner who could become pregnant should use highly effective contraception and avoid fathering a child for at least six months.16
In the manufacturer’s study, paclitaxel was detectable in semen in 60% of tested participants at one month, 39% at three months and 8.3% at six months. The effects on sperm and sperm production remain uncertain.16 Anyone planning a pregnancy should discuss timing and fertility questions with their urologist before treatment.
The available evidence is reassuring. Optilume does not remove prostate tissue and does not operate directly on the nerves that control erections.
ROBUST III assessed erectile function using the International Index of Erectile Function (IIEF) and found no significant deterioration through two years.2 ROBUST I likewise reported that erectile function remained unaffected at five years.4
This does not mean an individual can be promised no sexual change. The trials were not large enough to rule out uncommon effects, and men with strictures caused by pelvic injury, radiation or previous surgery may already have sexual difficulties related to the underlying condition.
Optilume is not designed to alter the prostate, bladder neck or ejaculatory ducts, so loss of forward ejaculation is not an expected routine effect in the way it can be after some prostate operations.
Clinical studies and reviews have not identified a consistent deterioration in sexual function.2, 6 However, ejaculation-specific outcomes have been studied less thoroughly than urinary symptoms and retreatment. It is therefore more accurate to say that the evidence is reassuring but not exhaustive, rather than claiming that ejaculation is guaranteed to remain unchanged.
Sexual function and reproductive safety are also different questions. Even if erection and ejaculation feel normal, the paclitaxel contraception precautions still apply because small amounts of the drug may remain in semen for months.16
Prostate size is not the relevant measurement for Optilume urethral-stricture treatment. The important factors are:
The strongest evidence applies to:
Most ROBUST III participants—89.9%—had a bulbar stricture, and the average length was 1.63 cm in the two-year report.2 ROBUST I was narrower still, including recurrent bulbar strictures no longer than 2 cm.4
Some real-world series include men who had never previously been treated, but robust randomised evidence for using Optilume first is not yet available. FIRST-CARE is a planned 140-patient randomised trial specifically studying treatment-naïve bulbar strictures no longer than 3 cm; its 2026 publication is a trial protocol, not a result.13
The pivotal trial excluded previous urethroplasty. A retrospective multicentre study subsequently included 33 men treated after urethroplasty and found short-term freedom from reintervention of 80.0%, compared with 88.9% among men without previous reconstruction. Median follow-up was only about three months, so this does not establish durability.8
A later 25-patient retrospective study reported functional success in 19 of 23 evaluable men—83% at 12 months—but its small size and uncontrolled design again require caution.10
Evidence outside the short bulbar/anterior setting is observational:
In the multicentre European cohort, diabetes independently predicted recurrence, with an odds ratio of 7.66.12 That is a large effect for a modifiable condition, and an argument for treating glycaemic control as part of the stricture plan rather than as a separate matter.
Outside the trials, independent cohorts have reported broadly consistent results: 73.8% success at a median eight months across 238 men in a Spanish multicentre study;17 90.7% free from reintervention at a mean nine months in a single US institution;18 82% free from reintervention at a median 22.9 months in a UK institutional review spanning mixed aetiologies including radiation-induced disease;7 and 76% stricture-free at 30 months in an Australian prospective cohort of high-risk strictures over 2 cm, with no complications.19 A meta-analysis of seven studies and 457 patients put the recurrence-free rate at about 81% with a 9.5% complication rate.5
These are retrospective and unblinded, with follow-up mostly under two years. They agree with the trial rather than extending it.
Longer strictures, complete or nearly complete obliteration, lichen sclerosus, previous hypospadias repair, radiation-associated disease, multiple strictures and bladder-neck or posterior narrowing may require a different reconstructive plan. Current European guidance says evidence outside the core ROBUST population is too limited for meaningful recommendations and advises study through a clinical trial or registry.14
These are the closest comparators because they also open the stricture endoscopically and usually allow relatively quick recovery.
For the recurrent short strictures studied in ROBUST III, Optilume was clearly more effective: anatomical patency at six months was 75% versus 27%.1 The trade-offs are exposure to paclitaxel, its specific contraception precautions, and greater device cost.
Optilume should not be assumed to give the same advantage after a first-ever endoscopic treatment; that question is still being tested.13
Urethroplasty removes or reconstructs the scarred segment. It is a larger operation, usually involving an incision, a longer catheter period and more recovery, but it remains the guideline-established definitive treatment for many recurrent strictures.
No randomised trial has compared Optilume directly with urethroplasty. Optilume may be attractive to someone who is medically unfit for reconstruction or who understands the trade-off and wishes to avoid or delay it. It should not be described as equally durable on the available evidence.
Repeated endoscopic treatment can also delay definitive reconstruction, so a consultation with a reconstructive urologist is valuable before choosing another minimally invasive procedure—especially for a young patient, a long or complex stricture, or disease that has already recurred several times.
Passing a catheter periodically can help keep the channel open in selected patients. It may avoid an operation but can be uncomfortable, burdensome and associated with bleeding, infection or false passage. It generally manages the tendency to narrow rather than removing the underlying scar.
Stents support the channel mechanically but leave a device in the urethra, at least temporarily. Migration, encrustation, tissue overgrowth, infection and difficult later reconstruction are concerns. Optilume leaves no implant behind.
Optilume offers
The cost: roughly three men in ten need another procedure within three to five years, plus paclitaxel exposure and its contraception rules.
Urethroplasty offers
The cost: an open operation, an incision, a longer catheter and a much larger recovery. Never compared against Optilume in a randomised trial.
One thing worth knowing before choosing again Repeated endoscopic treatment can make later reconstruction harder. If you are young, or the stricture is long, or it has already come back several times, seeing a reconstructive urologist before another minimally invasive procedure is worth the appointment.
Optilume may be worth discussing when someone has:
Before treatment, evaluation may include urine testing, a flow test, residual-urine measurement, cystoscopy and a retrograde urethrogram, an X-ray study using contrast to show the location and length of the narrowing.
Another approach may be more appropriate when:
The decision is not simply “small procedure versus big operation”. It is a choice between different probabilities of durable opening, different recovery burdens and different consequences if the stricture returns.
The 2026 European Association of Urology (EAU) guideline gives a strong recommendation to offer a paclitaxel-coated balloon for a short—under 3 cm—bulbar stricture recurring after at least two endoscopic treatments in patients who are unfit for, or unwilling to undergo, urethroplasty.14
The wording matters: the recommendation is not for every stricture and does not displace urethroplasty as the established reconstructive option.
In the UK, NICE recommends Optilume as an option for recurrent bulbar strictures in adults only when comparative data are collected on patient-reported outcomes, reintervention and adverse events.15 That reflects both the promising randomised evidence and the need for better comparative long-term information.
The wording of the recommendation is the point The EAU recommends a paclitaxel-coated balloon for a short bulbar stricture recurring after at least two endoscopic treatments, in men unfit for or unwilling to have urethroplasty. Every clause in that sentence is doing work. NICE goes further and asks for comparative outcome data to be collected alongside use.
The answer depends on the question being asked.
ROBUST III was a multicentre randomised controlled trial and showed a large six-month anatomical advantage over ordinary repeat endoscopic treatment.1
Multiple prospective and observational studies report substantial improvements. The findings are consistent in a 2024 meta-analysis, although pooling different designs and follow-up periods introduces uncertainty.5
ROBUST III provides prospective follow-up of the Optilume arm, with 77.8% free from reintervention at two years and 71% at three years.2, 3 The control group was not followed for the same duration, so long-term comparative certainty is weaker than the six-month result.
ROBUST I reports sustained benefit and 71.7% estimated freedom from reintervention at five years.4 It was a small, industry-sponsored, single-arm study with incomplete scheduled follow-up. Its findings support durability but do not settle how Optilume compares with urethroplasty over five years or longer.
Optilume is a well-supported endoscopic option for a short, recurrent male bulbar or anterior urethral stricture—particularly after ordinary dilatation or internal urethrotomy has failed more than once.
Its strongest evidence is the randomised ROBUST III trial. At six months, anatomical success was 75% with Optilume versus 27% with standard endoscopic treatment.1 Around 78% remained free from repeat intervention at two years, falling to 71% at three years in continued follow-up of the treatment arm.2, 3
The separate ROBUST I study suggests that benefit can persist: average IPSS improved from 25.2 to 7.2, Qmax from 5.0 to 19.9 mL/second, and estimated freedom from repeat intervention was 71.7% at five years.4 Those results are encouraging, but they come from a small single-arm study rather than a five-year randomised comparison.
Most complications are short-lived—principally blood in the urine, painful urination and urinary infection—but recurrence remains possible. The drug coating also creates a distinctive counselling issue: use a condom or abstain for 30 days, and if a partner could become pregnant, use highly effective contraception and avoid fathering a child for at least six months.16
Optilume’s main evidence-based advantage is that it offers a better chance of remaining open than another ordinary endoscopic treatment without the incisions and recovery of urethroplasty. Its main limitation is that it is less proven than urethroplasty as a definitive long-term solution, particularly for young men and for long, complex or non-bulbar strictures.
The most useful question is therefore not simply:
“Does Optilume work?”
For the population studied, it clearly can.
A better question is:
“Does my stricture match the evidence, and am I comfortable trading a smaller procedure now for a meaningful possibility of another procedure later?”
That decision is best made after the stricture’s exact length, location and cause have been mapped, and after discussing both Optilume and urethroplasty with a urologist experienced in urethral reconstruction.
Every figure on this page is traceable to one of these. Where a study is small, unrandomised or industry-sponsored, that is stated in the text rather than left in the footnote.
Where this leaves you
Location, length, density of scar, cause, and what has already been tried. A retrograde urethrogram and cystoscopy answer those questions. If your stricture would be better served by urethroplasty, I will say so — and repeated endoscopic treatment can make that operation harder.