urodynamics

My dad is 77 years old and had a radical prostectomy 20 years ago.  He began having a slight inconvenient drip a couple years ago.  A urologist did a cystoscopy on him about a year ago.  Since then, he is almostly completely incontinent.  Other doctors have suggested a test called urodynamics.  I am leary about having any other invasive procedures done on him.  Should he have this test done?  Is it possible his control will return at some later stage?  What other options have the most success?

Thank you for any helpful information.