Evaluate and manage urinary incontinence, including urodynamics, mid-urethral slings, pharmacotherapy and voiding dysfunction

In one line

Female urinary incontinence is a symptom, not a diagnosis: the entire management pathway is decided by which storage failure you are treating — stress (sphincter/support failure), urgency (detrusor overactivity), mixed, or the overflow that masquerades as either — and the consultant's job is to classify correctly, treat conservatively first, and reserve surgery and third-line therapy for the woman in whom mechanism and failed first-line therapy genuinely justify them.

The classification, definitions and continence physiology are assumed here from urinary incontinence at Intermediate; this develops the consultant layer — when urodynamics earns its place, how to choose between the mid-urethral sling and its alternatives in a post-mesh-pause world, how to sequence overactive-bladder therapy to third line, and how to recognise the voiding dysfunction that the inattentive registrar treats as the opposite disease.

Mechanism & pathophysiology

Continence is the product of two pressures and one reflex. Urethral closure pressure must exceed bladder (detrusor) pressure at rest and during effort; storage depends on a quiescent detrusor that does not contract until socially permitted. The switch between storage and voiding is a spinobulbospinal reflex: bladder-wall afferents ascend to the pontine micturition centre, which is held under tonic inhibition by the prefrontal cortex during storage and, when voiding is permitted, coordinates detrusor contraction with synchronous urethral-sphincter relaxation. Storage is sympathetic (hypogastric, β3-mediated detrusor relaxation and α-mediated bladder-neck tone) and somatic (pudendal, voluntary external sphincter); voiding is parasympathetic (pelvic, M2/M3 detrusor contraction). This wiring is not academic — it is why a sacral (S3) neuromodulator can restore inhibitory tone in refractory overactivity, why a β3-agonist augments storage without touching voiding, and why a spinal or pontine lesion produces detrusor–sphincter dyssynergia rather than simple incontinence. Stress and urgency incontinence are failures of these two systems, and they fail by different mechanisms that the treatment must match.

Stress urinary incontinence (SUI) is a failure of the urethral closure mechanism under a rise in intra-abdominal pressure. Two distinct lesions produce it, and distinguishing them changes the operation. The first is urethral hypermobility — loss of the suburethral hammock (the anterior vaginal wall and its attachments to the arcus tendineus and levator ani, the DeLancey support) so that the bladder neck and proximal urethra descend and rotate out of the abdominal pressure zone on straining; the urethra is no longer compressed against a stable backboard. The mid-urethral sling works precisely here, restoring a backstop at the mid-urethra against which the urethra kinks under stress. The second lesion is intrinsic sphincter deficiency (ISD) — the urethra itself fails to coapt, classically after pelvic radiation, multiple prior continence operations, ageing or denervation. ISD is the "low-pressure urethra" (a maximum urethral closure pressure below roughly 20 cmH₂O, or a Valsalva leak-point pressure under about 60 cmH₂O); it leaks with minimal provocation, often a fixed non-mobile urethra, and it is the SUI subtype most likely to fail a standard sling and to need a bulking agent, an autologous sling tensioned more snugly, or an artificial sphincter. The two coexist on a spectrum, but a fixed, leaking, previously-operated urethra is a different surgical problem from a hypermobile one.

Urgency urinary incontinence (UUI) is the storage symptom of the overactive bladder (OAB) syndrome — urgency, usually with frequency and nocturia, with or without incontinence and in the absence of infection or other pathology. Its urodynamic correlate, where one is sought, is detrusor overactivity: involuntary detrusor contractions during the filling phase. The pathophysiology is a loss of the normal cortical and afferent control of the micturition reflex — a combination of detrusor myogenic instability (spontaneous, propagating contractions in an electrically coupled detrusor), afferent hypersensitivity (urothelial signalling through purinergic and muscarinic pathways), and impaired central inhibition. This matters for drug choice: antimuscarinics target the M2/M3 receptors mediating detrusor contraction, while the β3-agonist promotes detrusor relaxation during storage through a different receptor entirely — which is why the two can be combined and why the β3-agonist avoids the antimuscarinic side-effect profile.

Mixed urinary incontinence is the coexistence of both, and the consultant skill is identifying the predominant symptom, because treating the wrong component first wastes time and an anti-incontinence operation done for a woman whose real problem is detrusor overactivity can worsen her urgency.

Voiding dysfunction and overflow is the trap that sits underneath all of this. Chronic incomplete emptying — from detrusor underactivity (ageing, diabetic cystopathy, neurological disease, pelvic surgery denervation), bladder outlet obstruction (a previous over-tight sling, severe prolapse kinking the urethra), or a combination — produces a chronically distended bladder that leaks by overflow, mimicking stress or urgency incontinence. The mechanism is the opposite of what it looks like: the bladder is too full and underactive, not overactive, and an antimuscarinic or a sling will make her worse. This is the single most important pathophysiological discrimination in the topic, and the reason a post-void residual is mandatory before any treatment.

Assessment

The assessment is built to answer three questions in order: which type, is there a red flag, and is the bladder emptying.

• History characterises the symptom. Leakage on coughing, lifting or exercise points to stress; leakage preceded by a sudden compelling urge points to urgency; both, with a dominant component, points to mixed. Continuous leakage (day and night, no provocation) is not ordinary incontinence — it signals a fistula or an ectopic ureter and demands a different work-up. Quantify severity (pads, fluid intake, caffeine, constipation, obstetric and surgical history, prior continence surgery, oestrogen status, neurological symptoms, and medication — diuretics, ACE-inhibitor cough, sedatives).
• The bladder diary (3 days, frequency-volume chart) is the highest-yield single investigation and is underused: it separates true incontinence from polyuria and nocturnal polyuria, quantifies functional bladder capacity, reveals fluid and caffeine excess, and demonstrates the urgency pattern objectively. It costs nothing and reshapes management more often than urodynamics.
• Examination assesses the pelvic floor, oestrogenisation and coexisting prolapse (incontinence and prolapse cluster, and a large prolapse can mask occult SUI that is unmasked once the prolapse is reduced). The cough stress test with a comfortably full bladder — demonstrable leakage synchronous with the cough — is the bedside confirmation of stress incontinence; immediate leakage confirms SUI, delayed leakage after the cough suggests a cough-provoked detrusor contraction.
• Urinalysis is mandatory in every woman to exclude infection (treat and reassess before labelling OAB), glycosuria and haematuria — the last because persistent unexplained haematuria with irritative symptoms mandates cystoscopy and upper-tract imaging to exclude malignancy, not an antimuscarinic.
• Post-void residual by catheter or bladder scan is non-negotiable before treatment: a high residual reframes the whole problem as voiding dysfunction/overflow and forbids both antimuscarinics and a sling until it is explained.
• The pad test quantifies leakage objectively (a standardised 1-hour or 24-hour weighed pad test) and is useful when symptoms and signs disagree or to document baseline severity, but it does not discriminate type and is not routinely required.

Urodynamics — reading the study. Multichannel cystometry derives the true detrusor pressure by subtracting abdominal (rectal/vaginal) pressure from intravesical pressure (p_det = p_ves − p_abd), so a pressure rise that appears on both channels is a straining artefact, not a detrusor contraction — the commonest misreading. During filling, phasic rises in p_det are detrusor overactivity; leakage synchronous with a cough and no detrusor rise is urodynamic stress incontinence; the abdominal/Valsalva leak-point pressure estimates sphincter competence (a low value flags ISD). The voiding (pressure-flow) phase distinguishes the two causes of a poor flow that look identical on uroflowmetry alone: a high detrusor pressure with a low flow is obstruction (the over-tight sling, the obstructing prolapse), whereas a low detrusor pressure with a low flow is detrusor underactivity — opposite problems needing opposite management, and the reason a flat trace plus a high residual must never be assumed to be "just" weak voiding. The indication and the limits. The consultant position is that it is not required before first-line conservative or pharmacological treatment, and not required in the uncomplicated index woman with clearly demonstrable, pure stress incontinence proceeding to a standard sling — the VALUE trial showed no outcome benefit from adding pre-operative urodynamics in exactly that group. It earns its place when the picture is not straightforward: predominant mixed symptoms before surgery, suspected voiding dysfunction or a raised residual, neurological disease, recurrent incontinence after a failed previous operation, symptoms that do not match the examination, or where a detrusor-overactivity component would change the surgical consent. Its limits are real — it is invasive, non-physiological (an artificial bladder fill in a laboratory does not always reproduce the woman's daily symptom), and a normal study does not exclude a symptom she genuinely has. Use it to answer a specific question that will change the plan, not as a reflex before every operation.

Management

Sequence the answer first-line (conservative) → second-line (the type-specific decision) → third-line (the refractory pathway), and resist the pull to operate or prescribe before conservative therapy has had a real trial, because most women improve without either.

First-line, shared across all types. Treat the reversible: stop the offending drug, manage constipation, control diabetes, treat infection, and address fluid and caffeine excess off the bladder diary. Weight loss is genuinely disease-modifying in the overweight woman — a structured reduction measurably lowers incontinence episodes. Topical vaginal oestrogen helps the postmenopausal woman with genitourinary syndrome and urgency. The cornerstone is supervised pelvic-floor muscle training (PFMT) for stress and mixed incontinence — at least three months, taught and supervised (not a leaflet), and bladder training for at least six weeks for urgency and mixed incontinence. These are not a holding measure before the real treatment; they are the treatment, and a substantial proportion of women need nothing more.

Stress incontinence — choosing the operation after the pause

When supervised PFMT fails and the woman wants surgery, the choice of operation is now a counselling-heavy decision reshaped by the mesh controversy.

The mid-urethral synthetic sling (MUS) — a tension-free strip of type 1 macroporous monofilament polypropylene placed at the mid-urethra — was, before the pause, the default: short, day-case, effective, with the largest evidence base of any continence operation. Two routes exist. The retropubic route (TVT, bottom-up through the retropubic space) and the transobturator route (TVT-O / TOT, through the obturator foramen, avoiding the retropubic space and its bladder/vessel risk). The TOMUS trial compared them head-to-head: at 12 months objective success was equivalent (80.8% retropubic vs 77.7% transobturator), but the complication profiles differed and that is what drives route selection — the retropubic route carried more voiding dysfunction requiring surgical revision (2.7% vs 0%) and a higher bladder-perforation risk, while the transobturator route carried more groin/thigh pain and neurological leg symptoms (9.4% vs 4.0%). Over five years the retropubic route held a small, non-significant efficacy advantage. The practical synthesis: retropubic for the woman with possible ISD or where durability is paramount (accepting the voiding and retropubic risks), transobturator where retropubic anatomy is hostile or bladder-perforation risk is high (accepting the groin-pain risk).

The mesh controversy and consent. Following the Cumberlege review and the 2018 high-vigilance restriction in the UK (mirrored by regulatory caution internationally), the synthetic MUS is no longer offered casually. The consent is now explicit and documented: the sling is a permanent implant, complete removal may be impossible, and the recognised complications — chronic pelvic/vaginal pain, dyspareunia, mesh exposure/erosion, and the difficulty of managing a complication — must be discussed alongside the high success rate, and the woman must be offered the non-mesh alternatives so that her choice is informed. This is not a reason to abandon a highly effective operation, but it is a reason the decision belongs in a specialist urogynaecology setting with full counselling and a recorded discussion.

The non-mesh alternatives, each a legitimate first-choice operation:

NICE NG123 frames the surgical choice as exactly this menu — colposuspension, autologous fascial sling, or retropubic mesh sling — offered with full discussion; the AUA/SUFU guideline lists the same set plus the single-incision sling, and both make urethral bulking an explicit option. The unifying message for the viva is that there is no single "best" operation post-pause; there is the right operation for this woman after informed counselling, and the consultant must be able to offer and perform (or refer for) the mesh-free options, not only the sling.

Recurrent stress incontinence and ISD are a separate, harder problem and should be assessed, not simply re-operated. A woman leaking after a failed sling needs the residual checked (is this obstruction, not recurrence?), urodynamics to characterise the mechanism, and a frank reappraisal: a fixed, poorly-coapting, previously-operated urethra is ISD, and a second standard sling done for a non-mobile urethra often fails. The options here are the autologous fascial sling (tensioned more snugly for a low-pressure urethra), repeat bulking, and — for the genuinely refractory, severe, multiply-operated woman — the artificial urinary sphincter, a tertiary-only device committing her to manual cuff operation and a real revision/erosion rate. Matching the operation to the mechanism, rather than repeating the one that already failed, is the consultant decision.

Overactive bladder — sequencing to the third line

For urgency-predominant incontinence the pathway is a clean escalation, and the discipline is to exhaust each rung before climbing.

• First line: bladder training (≥6 weeks) plus the shared lifestyle measures and topical oestrogen where atrophic.
• Second line: pharmacotherapy. The two classes are antimuscarinics and the β3-agonist. Antimuscarinics — oxybutynin, tolterodine, solifenacin — block detrusor M2/M3 receptors; they work, but the dose-limiting problem is the anticholinergic burden: dry mouth, constipation, blurred vision, and crucially cognitive impairment and a signal toward dementia with cumulative long-term exposure, which makes them a poor choice in the older or cognitively vulnerable woman and mandates counselling on total anticholinergic load (the woman already on an antihistamine, a tricyclic and an antiemetic is accumulating risk). Immediate-release oxybutynin is the worst offender for both dry mouth and central effects; extended-release and the more selective agents (solifenacin) are better tolerated. The β3-adrenoceptor agonist mirabegron relaxes the detrusor during storage through β3 receptors, with efficacy comparable to antimuscarinics but without the anticholinergic side-effect profile — its dry-mouth rate is close to placebo — making it the rational choice in the elderly, the cognitively impaired, or anyone already carrying a high anticholinergic load. Its caution is blood pressure: avoid in severe uncontrolled hypertension and monitor BP. Antimuscarinic and mirabegron can be combined when monotherapy is insufficient before escalating.
• Third line, after MDT review, for genuinely refractory OAB: the order is patient-led but the options are intradetrusor onabotulinumtoxinA, percutaneous tibial nerve stimulation (PTNS), and sacral neuromodulation (SNM).
  • OnabotulinumtoxinA (100 units intradetrusor as the initial dose, up to 200 units) chemodenervates the detrusor and is highly effective; the price is a real rate of incomplete emptying and clean intermittent self-catheterisation (CISC) and of urinary tract infection, so the woman must be willing and able to self-catheterise before it is offered, and the effect wanes at 6–12 months requiring repeat injection.
  • Sacral neuromodulation (a staged implanted S3 lead and pulse generator) modulates the sacral reflex; durable but resource-intensive and tertiary-only.
  • PTNS is the least invasive (weekly percutaneous tibial-nerve stimulation sessions) but demands repeated clinic attendance and is positioned for the woman who has failed or declines the other two.
  • Augmentation cystoplasty is a last-resort, major operation reserved for the rare refractory case, committing the woman to lifelong follow-up and usually CISC.

Mixed incontinence and voiding dysfunction

In mixed incontinence, treat the predominant symptom first and reassess — start with conservative therapy that helps both (PFMT plus bladder training), and be cautious about offering a sling to a woman whose urgency may worsen after it; many need the OAB component controlled before, or instead of, surgery. In voiding dysfunction / chronic retention, the priorities reverse: protect the upper tracts and bladder, establish emptying (CISC is the workhorse, occasionally a long-term catheter), treat the cause (relieve obstruction — loosen or divide an over-tight sling, reduce an obstructing prolapse), and never give an antimuscarinic to a poorly emptying bladder. A high residual discovered before treatment changes the whole plan; a new high residual after a sling is the over-tight sling until proven otherwise and may need urethrolysis or sling division.

Guidelines compared

The substantive disagreements are small and mostly about emphasis: all four bodies now agree pre-operative urodynamics is unnecessary in the straightforward index woman, all offer mesh and non-mesh surgery with informed consent, and all sequence OAB therapy conservative → drug → third-line. The post-pause shift — colposuspension and the autologous sling restored to first-choice status alongside (not behind) the synthetic sling, and the documented mesh consent — is the recent change to flag.

The South African divergence is access, not principle. Urodynamics, mid-urethral sling surgery, colposuspension, botulinum toxin and sacral neuromodulation are concentrated in a handful of regional and tertiary urogynaecology units; at district and most regional level the deliverable plan is conservative therapy done properly (supervised PFMT, bladder training, weight loss, topical oestrogen), oxybutynin for urgency with explicit attention to the elderly and to anticholinergic load, and timely referral of the woman who needs surgery or third-line therapy rather than improvising it locally. Naming the evidence-based option and the deliverable one — and the referral that bridges them — is the SA-context answer.

The evidence & the controversy

The defining controversy of the decade is the mesh pause, and the consultant must hold both halves of it without overreaching. The synthetic mid-urethral sling is one of the most studied and effective operations in gynaecology, and the harm — chronic pain and erosion — is a real but minority complication of a generally safe device. The regulatory response (the Cumberlege review, high-vigilance restriction, and in some systems a near-moratorium) was driven by the severity and difficulty-of-treatment of that minority complication and by a consent failure: women were not adequately warned that the implant was permanent and a complication could be life-altering and hard to reverse. The defensible position is neither "mesh is banned" nor "the pause was an overreaction" but that the sling remains a legitimate, highly effective option offered with rigorous, documented, fully informed consent in a specialist setting, with the mesh-free alternatives genuinely on the table — which is exactly why every consultant must again be fluent in colposuspension and the autologous fascial sling.

A second appraisal thread is urodynamics, where evidence has corrected practice. For years multichannel cystometry was a near-reflex before continence surgery; VALUE showed it adds no outcome benefit in the uncomplicated index woman with clearly demonstrable stress incontinence — identical success with and without it. The nuance candidates miss is that this is a statement about a specific population, not a blanket dismissal: in mixed symptoms, suspected voiding dysfunction, neurological disease and recurrent incontinence after failed surgery, urodynamics still answers questions that change the operation and the consent. "Urodynamics is never needed" is as wrong as "urodynamics before every sling".

The third shift is pharmacological: the β3-agonist has moved the OAB conversation away from the antimuscarinic-first reflex, particularly because of the accumulating signal linking cumulative anticholinergic exposure to cognitive decline and dementia in older people. The current direction of travel — actively weighing total anticholinergic burden, and preferring mirabegron in the elderly or cognitively vulnerable — is the appraisal point that distinguishes a current answer from a textbook one. The cost/access counter-pressure is the SA reality: mirabegron and botulinum toxin sit largely outside the public formulary, so the resource-stratified plan names the better-tolerated drug and what the patient in front of you will actually receive.

Two live questions sit at the edges of this. Duloxetine, the serotonin–noradrenaline reuptake inhibitor that increases sphincteric tone, has a licensed indication for moderate-to-severe SUI in some jurisdictions, but its modest efficacy, high discontinuation rate from nausea and a contested safety record mean it is not a routine first-line drug for stress incontinence and is best reserved for the woman who declines or is unfit for surgery — claiming it as standard stress-incontinence therapy overreaches. And the single-incision (mini) sling continues to divide opinion: shorter, less invasive and avoiding the retropubic and obturator passages, it is attractive, but its long-term durability relative to the standard mid-urethral sling is still debated, and it carries the same synthetic-mesh consent obligations — so it is an option to discuss, not a settled replacement. The international regulatory picture is itself non-uniform — from near-moratorium in some health systems to high-vigilance restricted use in others — which is part of why the consent conversation, not a blanket rule, governs practice.

Landmark trials & key evidence

Exam traps & red flags

• Calling overflow incontinence "stress" or "urge". A high post-void residual reframes the whole problem: the bladder is underactive and over-full, not overactive. An antimuscarinic or a sling makes her worse. Measure the residual before any treatment — this is the single discrimination that most often goes wrong.
• Continuous leakage treated as ordinary incontinence. Day-and-night unprovoked leakage signals a fistula or ectopic ureter and needs a dye/imaging work-up, not an antimuscarinic or a sling.
• Antimuscarinic in the cognitively vulnerable. Cumulative anticholinergic burden carries a cognitive/dementia signal; the older woman or the woman already on multiple anticholinergic drugs is a mirabegron candidate, and the burden must be counselled.
• Reflex pre-operative urodynamics — or refusing it when it is indicated. It adds nothing in the uncomplicated index woman (VALUE), but it remains necessary in mixed symptoms, suspected voiding dysfunction, neurological disease and recurrent incontinence after failed surgery. Both extremes are errors.
• Offering a synthetic sling without the mesh conversation. Post-pause, the consent must be explicit (permanent implant, removal may be impossible, chronic pain/erosion risk) and the mesh-free alternatives genuinely offered. Defaulting to a sling without that discussion is now indefensible.
• A new high residual after a sling. This is an over-tight/obstructing sling until proven otherwise — it may need urethrolysis or sling division, not reassurance.
• Botulinum toxin in a woman who cannot self-catheterise. Significant retention and the need for CISC are predictable; confirm willingness and ability to self-catheterise before offering it.
• Treating "OAB" without a urinalysis. Infection, glycosuria and unexplained haematuria each change the plan; persistent haematuria with irritative symptoms needs cystoscopy and upper-tract imaging, not an antimuscarinic.
• Operating on mixed incontinence without controlling urgency first. A sling can worsen urgency; the OAB component often needs treatment before, or instead of, surgery.
• Missing the SA access reality. Naming a tertiary-only therapy (botulinum toxin, SNM, urodynamics-led surgery) as "the plan" for a district patient without the referral pathway, or failing to deliver conservative therapy properly because surgery is unavailable, both miss the point.

Evidence anchors

• TOMUS — Richter et al., retropubic vs transobturator midurethral slings, N Engl J Med 2010
• TOMUS 5-year — Kenton et al., 5-year longitudinal followup after retropubic and transobturator midurethral slings, J Urol 2015
• VALUE — Nager et al., randomized trial of urodynamic testing before stress-incontinence surgery, N Engl J Med 2012
• ABC trial — Visco et al., anticholinergic therapy vs onabotulinumtoxinA for urgency urinary incontinence, N Engl J Med 2012
• SCORPIO — Khullar et al., mirabegron β3-adrenoceptor agonist phase 3 trial in overactive bladder, Eur Urol 2013
• SISTEr — Albo et al., Burch colposuspension versus fascial sling to reduce urinary stress incontinence, N Engl J Med 2007
• NICE NG123 — Urinary incontinence and pelvic organ prolapse in women: management (2019, reviewed 2025)
• AUA/SUFU — Surgical Treatment of Female Stress Urinary Incontinence guideline (2017, amended 2023)
• South African NDoH Standard Treatment Guidelines and Essential Medicines List — oxybutynin as the routinely available public-sector OAB agent; urodynamics, mid-urethral sling surgery, colposuspension, intradetrusor botulinum toxin and sacral neuromodulation concentrated at regional/tertiary urogynaecology units.