What is the Mid-Urethral Sling Tensioning (MUST) trial?

The MUST trial is a randomized controlled trial that compared two tension settings for mid-urethral sling placement in women with stress urinary incontinence. Researchers followed participants for five years to assess long-term continence rates and bladder side effects, including overactive bladder symptoms.

Can a mid-urethral sling cause overactive bladder?

Yes, in some people. Sling tension that is too tight can obstruct the urethra and trigger urgency and frequency -- a pattern clinicians call de novo overactive bladder. The MUST trial's five-year data helped clarify how sling tensioning choices affect this risk over time.

What treatments exist for overactive bladder that does not respond to lifestyle changes?

First-line options include bladder training and pelvic floor exercises. When those fall short, clinicians may consider anticholinergic or beta-3 agonist medications, botulinum toxin A injections into the bladder wall, or neuromodulation. A recent network meta-analysis found all three advanced options outperform placebo, with differing side-effect profiles.

How does botulinum toxin A help overactive bladder?

Botulinum toxin A (the same molecule used in Botox cosmetic treatments) blocks acetylcholine release at the detrusor muscle when injected cystoscopically. This reduces involuntary bladder contractions. Evidence supports its efficacy for neurogenic and non-neurogenic overactive bladder, though retreatment is typically needed every six to twelve months.

Is overactive bladder related to perimenopause or hormonal changes?

Yes. Estrogen receptors are dense throughout the lower urinary tract, and the estrogen decline of perimenopause and menopause can thin the urethral and bladder mucosa, lowering the threshold for urgency. Women managing both bladder symptoms and hormonal changes should have both evaluated together rather than in isolation.

Does sling surgery for stress incontinence guarantee long-term dryness?

No. The MUST trial and similar long-term data show that continence rates decline modestly over five years regardless of tension setting, and overactive bladder symptoms can emerge or persist post-operatively. Long-term follow-up with a clinician who knows your surgical history is important.

When should I see a clinician about bladder symptoms?

If urgency, frequency, nocturia, or leakage is disrupting sleep, work, or daily activities, that is reason enough to get an evaluation. Bladder symptoms are often undertreated because people assume they are a normal part of aging -- they are common, but not inevitable, and most respond well to structured care.

Overactive bladder 5 years after the Mid-Urethral Sling Tensioning (MUST) trial: what the evidence means for you

Creator: Dr. Jezwah Harris
Published: June 3, 2026

Bladder urgency is one of those symptoms that medicine has historically undertreated -- partly because it is common, partly because people assume it is just part of getting older, and partly because the conversation feels awkward to start. A landmark study published in 2025 gives us five years of data on what actually happens to overactive bladder (OAB) symptoms in women who undergo mid-urethral sling surgery for stress urinary incontinence. The findings are worth unpacking clearly, because they change how thoughtful clinicians approach the conversation.

Below we walk through what the MUST trial measured, what the five-year data shows, what it means if you are living with bladder symptoms now, and what the current treatment ladder looks like -- from the simplest behavioral steps through to the evidence on botulinum toxin A and neuromodulation.

What the MUST trial set out to answer

The Mid-Urethral Sling Tensioning (MUST) trial was a randomized controlled trial designed to answer a deceptively practical question: does the tension at which a mid-urethral sling is placed affect outcomes, and if so, for how long (https://pubmed.ncbi.nlm.nih.gov/42149649/)?

Mid-urethral slings -- thin strips of mesh placed under the urethra -- are the most common surgical treatment for stress urinary incontinence, the type of leakage triggered by coughing, laughing, or lifting. A Cochrane review of over 175 trials confirmed their efficacy (https://pubmed.ncbi.nlm.nih.gov/28756647/). But sling tension is a matter of surgical judgment, and that judgment has consequences. Too loose and the sling may not stop leakage. Too tight and it can partially obstruct the urethra -- which, in a clinical pattern that frustrates both patients and clinicians, can produce urgency and frequency symptoms that were not there before surgery.

The researchers followed participants over five years, tracking not just whether they stayed dry, but whether OAB symptoms -- urgency, frequency, urgency incontinence, nocturia -- emerged, persisted, or resolved over time. That long follow-up window is what makes this trial meaningful. Most surgical outcome data cuts off at one to two years. Five years is closer to real life.

What the five-year data shows

The headline finding is that overactive bladder symptoms are not a minor short-term side effect of sling surgery. They track women for years. Across both tension arms, a meaningful proportion of participants reported persistent or de novo OAB symptoms at the five-year mark -- symptoms that had either never fully resolved post-operatively or that appeared after the surgery itself (https://pubmed.ncbi.nlm.nih.gov/42149649/).

This matters for a few reasons. First, it tells us that the conversation about sling surgery cannot end at the one-year follow-up appointment. If you had a sling placed and you are now dealing with urgency or frequency that you did not expect, you are not unusual -- and you are not stuck. Second, it underlines that continence is not a single outcome. A woman can be objectively dry on a stress test and still have her quality of life significantly affected by urgency incontinence. Both deserve treatment.

The data also reinforces what the American Urological Association (AUA) and the Society of Urodynamics, Female Pelvic Medicine and Urogenital Reconstruction (SUFU) have said in their joint guidelines: OAB is a clinical syndrome defined by symptoms, not imaging or urodynamics alone, and it should be treated as such (https://pubmed.ncbi.nlm.nih.gov/31500851/).

Why overactive bladder is so often undertreated

A JAMA review of urinary incontinence in women found that roughly half of affected women never discuss their symptoms with a clinician (https://pubmed.ncbi.nlm.nih.gov/28898376/). The reasons are predictable: embarrassment, a belief that it is inevitable, and -- frankly -- a clinical culture that has not always made the conversation easy.

If you have had pelvic floor surgery and you are managing bladder symptoms silently, that is the wrong approach. The same goes if you are in perimenopause and have noticed your urgency worsening. Estrogen receptors are dense throughout the lower urinary tract. As estrogen drops during perimenopause and menopause, the urethral and bladder mucosa thin, the pelvic floor loses support, and the threshold for urgency falls. Research has found a significant association between genitourinary syndrome of menopause and OAB symptoms in midlife women (https://pubmed.ncbi.nlm.nih.gov/29351118/). That is worth addressing alongside -- not instead of -- the bladder symptom itself.

If you have been reading our piece on perimenopause symptoms and HRT, you will recognize the overlap. Bladder health is part of the same hormonal picture.

The treatment ladder: what clinicians look for and what the evidence supports

Treatment for OAB is stepwise. The AUA/SUFU guideline is explicit about this: start with the least invasive effective option and escalate based on response (https://pubmed.ncbi.nlm.nih.gov/31500851/).

Behavioral and lifestyle measures come first. Bladder training -- systematically extending the interval between voids -- reduces urgency episodes in controlled trials. Pelvic floor muscle training reduces leakage. Caffeine and alcohol both lower the bladder urgency threshold; reducing them is not a minor intervention. For many people, structured behavioral therapy alone achieves significant improvement.

Pharmacotherapy is second-line. The two main classes are anticholinergics (oxybutynin, tolterodine, solifenacin, and others) and beta-3 adrenergic agonists (mirabegron, vibegron). A pooled analysis of mirabegron trials found significant reductions in urgency incontinence episodes versus placebo (https://pubmed.ncbi.nlm.nih.gov/27663880/). Beta-3 agonists are generally preferred in older adults because anticholinergics carry cognitive risk at higher doses -- a tradeoff that matters and should be named explicitly before prescribing.

Third-line options are where the recent network meta-analysis is particularly useful. A 2025 analysis compared botulinum toxin A injections, intravesical instillations, and neuromodulation for lower urinary tract dysfunction (https://pubmed.ncbi.nlm.nih.gov/42203154/). All three outperformed placebo. Botulinum toxin A -- the same molecule used in cosmetic applications like those we describe in our complete guide to Botox -- is injected cystoscopically into the detrusor muscle, blocking the involuntary contractions that drive urgency incontinence. A systematic review and meta-analysis in European Urology found it superior to anticholinergics for certain OAB presentations, particularly when urgency incontinence is the dominant symptom (https://pubmed.ncbi.nlm.nih.gov/33341307/). The limitation is that retreatment is needed roughly every six to twelve months, and there is a small risk of urinary retention requiring temporary self-catheterization.

Sacral neuromodulation (SNM) and posterior tibial nerve stimulation are the other third-line options. SNM involves a small implanted device that modulates the sacral nerves governing bladder function. Evidence for both is solid; the choice between them depends on symptom pattern, patient preference, and surgical candidacy.

What this means if you had sling surgery and have bladder symptoms now

The MUST trial's five-year data does not mean sling surgery was the wrong choice. Mid-urethral slings remain the most evidence-supported surgical treatment for stress incontinence (https://pubmed.ncbi.nlm.nih.gov/28756647/), and for many women the procedure delivers durable dryness with acceptable side effects. What the data does mean is that OAB symptoms after sling surgery deserve longitudinal attention -- not a one-time post-op sign-off.

If you are five years out from a sling and you are managing urgency, frequency, or urgency leakage, here is what clinicians look for in a proper evaluation: a symptom diary (urgency patterns, void frequency, fluid intake), a post-void residual to rule out obstruction, a urinalysis to exclude infection, and -- depending on your history -- possibly urodynamic testing to characterize what is driving your symptoms. The goal is to match the right intervention to what is actually happening in your bladder, not to assume a single diagnosis.

It is also worth asking whether hormonal factors are in play. If you are in perimenopause or menopause, local vaginal estrogen -- which carries a different risk profile from systemic hormone therapy and is generally considered safe for most women -- can reduce urogenital atrophy and lower urinary urgency thresholds. That is a conversation your clinician should be having with you as part of a complete evaluation.

For our broader perspective on how integrative medicine approaches conditions that touch multiple systems at once, see our aesthetic medicine concierge guide. The same principle applies here: bladder health does not live in isolation from hormonal health, pelvic floor health, or quality of life.

The honest bottom line

Five years of MUST trial data confirms what many women already know from lived experience: bladder symptoms after pelvic floor surgery can be persistent, are not well-captured by short-term follow-up, and deserve ongoing clinical attention rather than a shrug. The good news is that the treatment options -- from structured behavioral therapy through pharmacotherapy to botulinum toxin A and neuromodulation -- are effective, evidence-supported, and more accessible than most people realize.

If urgency, frequency, or leakage is disrupting your sleep, your work, or your confidence, that is not something to manage quietly. It is something to bring to a clinician who will actually take the time to evaluate it properly.

At NoMi Beach Health, Dr. Jezwah Harris (NP, JD, MBA, FNP-BC, MEP-C) spends the visit time to work through exactly this kind of layered picture -- bladder symptoms, hormonal context, surgical history, and lifestyle. If this sounds like you, book a new-patient visit at our services page or call us at (786) 744-5152. We will look at the whole picture and tell you what the evidence actually supports.