Overactive bladder and urgency urinary incontinence — structured oral station (12 minutes)

Opening prompt — "How would you take this history and what is your working diagnosis?"

Model response — say it in this order: ^[1][3]

• "I'd take a focused lower-urinary-tract history using the ICS 2002 vocabulary: urgency, frequency (more than 8 voids/day), nocturia, urge incontinence — and the three-day bladder diary is the single most informative investigation at first visit."^[1][3]
• "I'd quantify bother with the Patient Perception of Bladder Condition (PPBC) or the OAB-q, and ask about caffeine, fluid intake, constipation, sexual function, sleep and mood."^[3]
• "The working diagnosis is overactive bladder syndrome — OAB-wet subtype — urgency with urge incontinence, plus frequency and nocturia, in the absence of infection. Detrusor overactivity is the urodynamic finding that may or may not be present, and I'd reserve urodynamics for refractory disease."^[1]

Examiner is listening for: the OAB/DO distinction in the first 30 seconds; the bladder diary named as the diagnostic anchor; bother quantified; comorbidities captured. ^[3]

Probe 1 — "She tried oxybutynin IR and stopped because of dry mouth and foggy thinking. What would you do next?"

• "I would not retry an antimuscarinic at higher dose or a different non-selective one — oxybutynin IR crosses the blood-brain barrier and cohort data show it carries an excess dementia signal in older women (Painter 2026, Iwai 2026)."^[6]
• "My next rung is mirabegron 25 mg orally once daily, titrated to 50 mg based on efficacy and tolerability. It is a β3-adrenoceptor agonist; the Nitti 2013 pooled phase III analysis reported dry mouth at placebo level, no measurable cognitive-decline signal, and significant improvements in incontinence, frequency, urgency and volume voided."^[2]
• "Pre-treatment: baseline blood pressure (severe uncontrolled hypertension is a contraindication), review of interacting drugs (digoxin, metoprolol), and counselling on BP surveillance during treatment."^[2][3]

Examiner is listening for: not retrying oxybutynin; choosing mirabegron with dose and route; cognitive-safety reasoning; cardiovascular safety reasoning. ^[6]

Probe 2 — "She returns at 12 weeks with 50% improvement but ongoing urge incontinence. What is your escalation?"

• "Reassess bother and confirm incomplete response with a 3-day bladder diary. Up-titrate mirabegron to 50 mg once daily if tolerated and BP allows — greater efficacy at 50 mg was demonstrated in the Nitti 2013 pooled analysis."^[2]
• "If she is still bothered at 12 weeks on mirabegron 50 mg, add an M3-selective antimuscarinic such as solifenacin 5 mg daily (the STAR trial showed solifenacin 5 mg produced a 44% additional reduction in incontinence episodes versus tolterodine ER 4 mg at 4 weeks)."^[3]
• "If two lines of pharmacotherapy still leave her with bothersome urge incontinence, that is refractory OAB and I move to invasive third-line therapy."^[3]

Probe 3 — "She does not want long-term medication. What do you offer?"

• "Three recognised third-line options for refractory OAB with urge incontinence: intradetrusor onabotulinumtoxinA 100 U, sacral neuromodulation (InterStim) and percutaneous tibial nerve stimulation (PTNS)."^[3][4]
• "For onabotulinumtoxinA in idiopathic OAB, the dose is 100 U intradetrusor, sparing the trigone, in approximately 20 injection sites. The pooled phase III analysis (Sievert 2014) reported reductions of roughly 2.5-3 incontinence episodes per 24 h. The key complication is intermittent self-catheterisation in approximately 5-10% with 100 U, plus UTI risk. She must be willing to self-catheterise before I book the procedure."^[4]
• "For sacral neuromodulation, the staged technique (Amend 2011): a tined lead is introduced through the S3 foramen under fluoroscopic guidance; a 2-4 week test phase precedes commitment to the permanent InterStim II impulse generator. Roughly 50-80% proceed to permanent implant."^[5]
• "PTNS — 12 weekly 30-minute sessions with a needle above the medial malleolus — modest efficacy versus sham, suitable for patients declining invasive therapy."^[3]

Probe 4 — "What is the onabotulinumtoxinA actually doing inside the bladder?"

• "It is not pure motor blockade. The ICI-RS 2018 think tank (Malde) synthesised the mechanism: BTX-A reduces bladder sensory input by inhibiting neurotransmitter release from urothelial and suburothelial afferents, modulates ATP and acetylcholine release, and may have central effects via altered spinal signalling. Urodynamics show increased bladder capacity and compliance and reduced detrusor pressures during filling; post-void residuals rise in a dose-dependent fashion, which is why 100 U is used in idiopathic OAB and 200 U reserved for neurogenic DO."^[5]

Probe 5 — "She asks whether long-term oxybutynin could have affected her memory. What do you say?"

This is a scored domain — communication skills. Demonstrate it out loud. ^[6]

• "Acknowledge her concern explicitly. "You're right to ask — and the answer is yes, that is a recognised concern with the older bladder tablets. Cohort studies have shown a measurable increase in the risk of cognitive decline and dementia in older women who take oxybutynin or tolterodine regularly over months to years. That is exactly why I am moving you to mirabegron, which does not carry that signal.""
• "Validate her lived experience: 'The foggy thinking you noticed was real, not in your head. Stopping the oxybutynin is the right move.'"
• "Offer a simple re-assessment: "If you would like, we can repeat your MoCA in three months on mirabegron to see whether the thinking clears.'"
• "Discuss with her GP the anticholinergic burden review for any other medicines she may be taking (antihistamines, antidepressants, bladder drugs)."^[6]

Examiner is listening for: explicit acknowledgement; lay translation of the cohort evidence; concrete next step; respect for her autonomy. ^[6]

Probe 6 — "What will you do at follow-up?"

• Pharmacotherapy review: at 4 weeks for efficacy and side effects, 12 weeks for dose titration, then 6-monthly. Re-screen cognition annually in older women. Annual anticholinergic burden review.^[3]
• OnabotulinumtoxinA review: symptomatic review at 6-12 weeks; document PVR; offer repeat injection when effect wanes (typically 6-12 months), with a minimum 3-month interval between doses.^[4]
• Sacral neuromodulation review: device checks; battery life 5-10 years; MRI-conditional device; lead migration suspected with sudden return of symptoms.^[5]
• GP shared care: once stable on a tolerated regimen; red-flag pathway for haematuria, retention, recurrent UTI.^[3]