Generally, it's touted as being very safe.  However, I highly advise asking the urologist how many surgeries has he done and how many were successful, along with all the other usual questions.  My dad is also on coumadin and is 78 years old.  (no strokes)  He wasn't able to urinate easily because of his prostate, even after trying various medications.  So, the urologist suggested the green light laser.  After the surgery, my dad leaked continuously.  The urologist said the surgery went fine, and this was normal.  After a month or so, he consulted with a second urologist who told him the first urologist lasered off his sphincter which is the valve that opens and closes to release or stop the flow of urine!  The second urologist put in an artificial sphincter.  So far that hasn't worked either.  Now he's using a catheter that he inserts himself every 4 to 6 hours.  It's better than the Depends but a far cry from the safe out-patient surgery that the Green Laser is supposed to be.  In hindsight, I'd ask LOTS of questions: how often is the machine calibrated, can I see the machine, etc. anything you can think of!  Hope this helps.