How can I differentiate between obstructive and non-obstructive causes of acute urinary retention in a primary care setting?

To differentiate between obstructive and non-obstructive causes of acute urinary retention (AUR) in a primary care setting, consider the following clinical approach:

• History and Symptoms: Obstructive causes often present with a history of lower urinary tract symptoms (LUTS) such as hesitancy, weak stream, intermittency, and incomplete emptying, commonly due to benign prostatic hyperplasia (BPH) in men. Non-obstructive causes may be related to neurological conditions or medications affecting bladder contractility and sensation ².
• Physical Examination: Abdominal examination may reveal a palpable bladder in retention. Digital rectal examination (DRE) can assess prostate size and consistency to suggest obstruction. Neurological examination may identify signs of neurogenic bladder contributing to non-obstructive retention ¹.
• Urinary Catheterisation: Immediate catheterisation is recommended to relieve retention regardless of cause ². The ease of catheter insertion may provide clues; difficult catheterisation may suggest anatomical obstruction.
• Response to Alpha-Blockers: In men with suspected obstructive retention, alpha-blockers can be offered before catheter removal to improve bladder outflow by relaxing smooth muscle at the bladder neck and prostate ². Alpha-blockers are not recommended for bladder emptying problems caused by neurological disease ¹.
• Referral and Further Investigation: If non-obstructive causes are suspected (e.g., neurological disease), or if initial management fails, referral for specialist assessment including urodynamic studies may be necessary to differentiate causes definitively ¹,².