Urinary retention is the inability to empty the bladder completely. Urinary retention can be acute or chronic. Acute urinary retention happens suddenly and lasts only a short time. People with acute urinary retention cannot urinate at all, even though they have a full bladder. Acute urinary retention, a potentially life-threatening medical condition, requires immediate emergency treatment. Acute urinary retention can cause great discomfort or pain.Urinary retention is an inability to completely empty the bladder. Blockage can be caused by benign prostatic hyperplasia (BPH), urethral strictures, bladder stones, a cystocele, constipation, or tumors.