In adult males, urinary retention is commonly caused by obstruction to the urethra by a benign or malignant enlargement of the prostate. An acute urethritis or prostatitis can also be responsible. Acute retention occurs much less frequently in females. The only anatomic cause of urinary retention in females is acute inflammation around the urethra (e.g., from herpes).
The state in which the individual experiences incomplete emptying of the bladder. High urethral pressure inhibits voiding until increased abdominal pressure causes urine to be involuntarily lost, or high urethral pressure inhibits complete emptying of the bladder.