Others are treated with ureteroscopy, in which a scope is passed through the urethra and bladder and up the ureter into the kidney.

CNN: What can I do for kidney stones?

Complicating matters further: The urethra passes through the center of the prostate and must be reconnected back to the bladder once the prostate is removed.

FORBES: Men, Cancer & Hope

In bladder instillation, the prescription medication dimethyl sulfoxide, or DMSO, (Rimso-50) is placed into your bladder through a thin, flexible tube (catheter) inserted through the urethra.

CNN: Interstitial cystitis