Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Urinary Retention ?
    ### Response:
    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.
    