Below is an instruction from Human. Write a response.
    ### Instruction:
    What causes Urinary Retention ?
    ### Response:
    Urinary retention can result from
                
- obstruction of the urethra  - nerve problems  - medications  - weakened bladder muscles
                
Obstruction of the Urethra
                
Obstruction of the urethra causes urinary retention by blocking the normal urine flow out of the body.
    