I've had at least 20 at this point. I had one prior to my transplant to confirm necessity of transplant, and after a transplant, you have a series of them. One per week for the first month, then every-other-week for several months, then once a month for a few months, then once every 3 months for a while, then every 6 months. I'm almost 4 years post transplant, and it's once a year now. My 4th year tests will be done at the end of October, and one of the doctors told me that they may not even need to do one this year, because the tests have not shown any amount of rejection so far that are at a level that would need treatment. The biopsy is done through the neck, groin or arm (I've had all 3). It can be used to confirm disease, which they did prior to my transplant to get me on the list. And then after transplant, it's done to see if I'm experiencing any rejection. I hope this was helpful.