Chronic urinary retention and post‑obstructive diuresis
Concise, exam‑focused guidance on recognising and managing chronic urinary retention (CUR) and the potentially hazardous polyuric response after decompression - post‑obstructive diuresis (POD).
Framed for UK emergency practice and aligned with national guidance on catheter use, catheter‑associated infection prevention and ED governance (NICE CG97, CG139, QS61; GOV.UK CAUTI tools; RCEM). Note: no single UK national protocol for POD was identified; local/urology protocols should be followed where available.
Definitions and clinical significance
- Chronic urinary retention (CUR): usually painless, gradual inability to empty the bladder completely with a large post‑void residual (PVR). Patients may be asymptomatic or present with overflow incontinence, frequency, hesitancy or recurrent UTIs. Common in men with benign prostatic enlargement, and in patients with neurogenic bladder or obstructing lesions (NICE CG97).
- Post‑obstructive diuresis (POD): a polyuric response after relief of significant bladder outlet obstruction. The spectrum ranges from modest, self‑limited diuresis to massive, sustained polyuria causing hypovolaemia, hypotension, acute kidney injury and electrolyte disturbances (especially Na+ and K+). Mechanisms include excretion of retained solutes, restored glomerular filtration and temporary tubular concentrating impairment.
Clinical implication: CUR may coexist with renal impairment or hydronephrosis and usually requires drainage. Decompression can be immediately beneficial but mandates active monitoring for POD.
Causes and contributors
- Common causes of CUR: benign prostatic enlargement, urethral stricture or malignancy, neurogenic bladder...