Bladder pain syndrome / interstitial cystitis — structured SAQ (15 marks)

(a) Differential diagnosis and mandatory exclusion workup (5 marks)

One mark per differential with the test that excludes it. ^[1][6]

• Bacterial urinary tract infection — urine culture (sterile in BPS; if culture-positive it is UTI, not BPS).
• Bladder cancer / carcinoma in situ — urine cytology and cystoscopy with biopsy of any red patches.
• Overactive bladder — symptom pattern (urgency without pain) and urodynamics if needed.
• Endometriosis with bladder involvement — cyclical pain, anterior fornix nodule, MRI pelvis.
• Vulvodynia, urethral syndrome, pelvic-floor dysfunction, painful bladder syndrome from other cause — clinical assessment including Q-tip test and pelvic-floor tone.^[1]

(b) NIDDK cystoscopic criteria (3 marks)

One mark per criterion plus the threshold. ^[6]

• Hunner lesion — reddened mucosal patch with central scar, waterfall hyperaemia, fibrin deposition.
• Glomerulations — ≥10 punctate haemorrhages per quadrant in ≥3 of 4 quadrants.
• Hydrodistension technique — fill bladder to 80 cm H2O for 2–5 minutes under general anaesthesia; inspect after drainage; take multiple biopsies for ESSIC histology and to rule out CIS.^[6]

(c) Stepwise pharmacological management (5 marks)

One mark per agent with dose and key adverse effect. ^{[1][3][4][5][6]}

Plus intravesical DMSO 50% via catheter every 2 weeks — a rescue intravesical therapy between oral and surgical options.^[1][4]

(d) Long-term pentosan polysulfate surveillance (2 marks)

• Pigmentary maculopathy — annual ophthalmology review from year 5 onward (fundoscopy and OCT).^[8]
• Hepatic toxicity and bleeding (rare) — periodic LFTs; counsel patients on the months-long delay before benefit, and on avoidance of concurrent anticoagulants where possible.^[8]