Dear "Stpfan44",
An initial drawing of a blood sample can determine whether there is enough of a "match" between the potential donor and the recipient to make a successful transplant possible. A LOT more blood is drawn to help determine the health of the kidneys, the general health of the donor, whether the donor carries transmissible disease, etc. Then there are other tests (cardiogram, chest x-ray, cancer checks, CT or other scans, possibly a stress test, 24-hour urine collection, etc.) both to evaluate the functioning of the donor's kidneys and the over-all health of the donor. They have to be fairly sure that the donor can give a kidney without harming his/her own health, that the donated kidney will be strong enough to take care of the recipient, and that no diseases are passed along with the kidney. Then there are interviews/tests to evaluate the psychological status of the donor, to be fairly sure that the donor is acting freely and well-informed, and will be able to handle the post-op possibility of stress/depression especially if the transplant turns out to be unsuccessful. A social worker may also interview the potential donor about ability to handle the financial losses often involved.
If any of these tests raise questions they may have to be repeated, or be evaluated by different doctors.
All of this can take time, and some hospitals may deliberately move slowly so as to give the potential donor plenty of space in which to decide not to proceed. So, some hospitals proceed more quickly, while others may go more slowly. But there is always a LOT of testing involved.
best wishes,
Fr. Pat