TURP-like syndrome without surgery: severe dilutional hyponatraemia following prolonged sterile water bladder washouts for radiation cystitis: a case report.

Severe dilutional hyponatraemia is a recognised complication of transurethral resection of the prostate (TURP syndrome) caused by systemic absorption of hypotonic irrigation fluid, but similar events outside the operative setting are rarely reported. We describe a 77-year-old White male with radiation cystitis who underwent 12 days of sterile water bladder washouts alongside continuous 0.9% saline bladder irrigation for persistent haematuria. Serum sodium declined from 132 to 112 mmol/L and improved only after bladder washouts and irrigation were discontinued. Cystoscopy confirmed radiation cystitis with mucosal ulceration. The clinical course strongly suggests that systemic absorption of electrolyte-free sterile water caused the profound hypotonic hyponatraemia, whereas concurrent absorption of isotonic saline contributed to extracellular volume expansion. This case highlights that prolonged sterile water bladder washouts may produce a TURP-like syndrome in the absence of surgery. Early recognition, serial electrolyte monitoring and prompt source control are essential to prevent potentially life-threatening complications.