Having had a stent for a kidney stone, I can tell you that it is a soft piece of rubber. Its insertion should not cause you to bleed. You may or may not be instructed to stop warfarin for the laser insertion. If you do stop it, then you should have what is called bridge therapy. Usually this is done as an outpatient with a low molecular weight heparin such as Lovenox. The laser is also encased in a soft material. The greatest risk for bleeding is when the stone fragments pass down the ureter. These fragments came be passed up to six weeks after the surgery. The last time I had it done it was the day after Thanksgiving and I passed the biggest stone fragment in mid-January. So the doctor may decide to continue the warfarin since the actual procedure is not the major time for bleeding. Be sure to discuss this with your urologist. If the urologist wants you to stop warfarin for a week before and after the procedure with no bridging, find another doctor.