Urinary retention is the most common urological emergency and more than 95% of cases occur in men. Acute urinary retention (AUR) is defined as the sudden inability to pass any urine voluntarily associated with a painful, palpable or percussable bladder. In chronic urinary retention (CUR) there is a non‐painful bladder, which remains palpable or percussable after the man has passed urine, with a post-void residual volume > 300 ml. In acute on chronic urinary retention no urine can be voluntarily passed but the condition is relatively painless and the residual volume on catheterisation is > 1.5 litres.