How can I tell if I'm experiencing urinary retention?

Depends. Acute urinary retention, or the inability to void at all, is extremely uncomfortable and makes itself known. He more concerning thing long term is silent worsening of chronic retention, or incomplete bladder emptying. This can cause severe bladder and, more importantly, kidney damage. If you don't think you empty your bladder after voiding, then seek out a urologist to help determine your risk.