Sling or sphincter?

What did MASTER find?

Using its strict primary patient-reported definition, incontinence remained common at twelve months — 87.0% after sling and 84.2% after sphincter — and the sling met the prespecified criterion for non-inferiority.¹

That headline sounds disappointing until you read the rest. The definition was demanding, and it does not distinguish a man soaking six pads a day from one with an occasional drop when he sneezes.

This is precisely why the 2025 BAUS consensus went to the trouble of standardising the word. Continence after prostatectomy is to be defined as total control without any pads or leakage — a deliberately unforgiving bar, chosen so that published figures can be compared with one another rather than each paper marking its own homework.¹³ When you are given a percentage, the first question is always which definition produced it.

Did men actually improve?

Substantially. ICIQ-UI Short Form scores fell from 16.1 to 8.7 after sling and from 16.4 to 7.5 after sphincter. Quality of life improved and satisfaction was high in both arms.¹

Two further details from the trial deserve stating, because each side tends to quote only one of them. Most secondary outcomes favoured the sphincter. And serious adverse events were somewhat more frequent with the sphincter too.² That is the actual shape of the trade: a bit more benefit, a bit more risk.

What the trial could not settle

Non-inferiority on one endpoint is not equivalence across all patients, and MASTER recruited a broad group.

Where the comparison has been made in men with moderate leakage specifically, the sphincter has generally come out ahead. A direct comparison found it outperformed the sling in moderate stress incontinence,³ a systematic review and meta-analysis reached the same conclusion with an acceptable complication rate,⁴ and a large retrospective analysis of patient selection and postoperative continence found the same pattern.⁵

The general principle in the literature is consistent: for mild leakage in a man with no major urethral risk factors, a sling is a reasonable choice.⁶⁷⁸ As severity rises, or where there has been radiotherapy or urethral compromise, the evidence moves towards the sphincter.⁶⁹¹⁰

The group the trials left out

If you have a urethral stricture, or have had a urethroplasty, the comparative evidence barely covers you.

Sling data in this group are thin precisely because trials tended to exclude men with unresolved strictures or previous sphincter and stricture complexity.²¹¹ That makes the sphincter the better-studied reconstructive option for men with a compromised urethra — but not a risk-free one, since the same history raises the chance of the device eventually needing to come out. I have set out those numbers in the note on device failure.

This is one of the few places in urology where "there is no evidence" is the accurate answer rather than a way of avoiding the question.

Why might someone still choose a sling?

No pump to operate, no fluid-filled mechanism, nothing to think about when you want to pass urine. In carefully selected mild-to-moderate leakage those are real advantages, and for a man with arthritic hands or reduced dexterity they can be decisive — a sphincter you cannot work is not a sphincter.

Why might someone choose a sphincter?

It is the most reliable option for more severe sphincteric leakage and has by far the longest track record.⁷¹² It is also what the guidance recommends after radiotherapy.

The cost is mechanical: a device to operate, and the expectation that revision may eventually be needed.

How should the choice actually be made?

Leak severity and pad weight first — measured, not estimated. Then previous radiotherapy, urethral anatomy and any history of stricture surgery, bladder function, manual dexterity, how you feel about an implant you have to operate, and what you are actually trying to achieve.

A cystoscopy before either operation is not optional. It is how an unrecognised stricture or bladder-neck contracture is found before a cuff or a tape is placed around it.

The national consensus puts it in three lines, and they are worth having in front of you.¹³ For mild to moderate leakage the sling and the sphincter are treated as comparable options, and the choice is genuinely yours to make. For moderate to severe leakage, and for any man who has had pelvic radiotherapy, the sphincter is the one to be offered in preference. And there is one outright exclusion: a man with a previous urethral stricture should not be offered a sling at all.

Bottom line

Both operations substantially reduce symptoms and improve quality of life, even though strict complete continence was uncommon in the trial. The sphincter tended to do better on several secondary outcomes and had somewhat more serious adverse events. The right choice depends on severity, anatomy, previous treatment and which trade-offs you mind.

The real-world number worth holding on to is that only about one man in seven was completely dry at a year, while roughly two-thirds were substantially improved. That is a good operation described honestly.

Two things patients are almost never told. Surgeons past two hundred cases have around half the re-operation rate of those who have done five or fewer — so where this is done matters as much as which is chosen. And if you have had urethral surgery, the comparison you are being offered has largely not been studied in men like you; that should make the conversation longer, not shorter.

Worth reading alongside: what the operations involve, and why referral so often does not happen.