Synopsis
Detect lower- and upper-tract obstruction early, drain the urinary system at the correct level, treat infected obstruction as an emergency and manage post-decompression physiology safely.
- Post-renal AKI occurs when urine-flow resistance affects both kidneys, a solitary functioning kidney, or the lower tract below both ureteric outlets; unilateral obstruction with two functioning kidneys may not raise creatinine.
- Lower-tract causes include benign prostatic enlargement, prostate or bladder malignancy, urethral stricture, clot, constipation and neurogenic bladder; upper-tract causes include stones, tumour, retroperitoneal fibrosis and iatrogenic ureteric injury.
- Pain may be absent in chronic retention, neuropathy and retroperitoneal disease. Ask about hesitancy, weak stream, incomplete emptying, overflow, loin pain, haematuria, pelvic cancer and recent urinary or gynaecological surgery.
Key red flags
Painful inability to void, suprapubic distension and a large residual volume suggest acute retention. Older or neuropathic patients may instead have painless overflow, confusion or renal failure from high-pressure chronic retention.
Investigation priorities
Identify lower-tract retention and rule out a simple mechanical explanation for apparent anuria.
Management branches
A large residual, palpable bladder, painful retention or blocked urethral catheter is suspected.
- 1. Assess haemodynamics, lower urinary history, urethral trauma risk, previous difficult catheterisation and visible bleeding, and obtain a bladder volume where it will not delay relief.
- 2. Perform urethral catheterisation with appropriate asepsis and anaesthetic gel by a competent clinician; stop and seek urology if resistance, false passage or urethral injury is possible.
Key medicines
Empirical intravenous antimicrobial for infected obstructionStart promptly using the current local urosepsis regimen, adjusted for allergy, prior cultures, renal function and resistance risk; refine after blood, urine and drainage cultures return.
Alpha-1 blocker for selected bladder-outlet obstructionUse the locally preferred licensed oral preparation and standard adult regimen after reviewing blood pressure, interactions and the proposed timing of a supervised trial without catheter.