It has been reported that some transplant hospitals may may deliberately delay giving test results to potential donors, in order to give the potential donors plenty of time to think it over and perhaps just gracefully back out by not asking further about the test results. The hospital MIGHT be thinking "If this person REALLY wants to donate, and is not just being pressured to do so, she/he will take the initiative to ask about the results". So, as noted elsewhere above, politely but insistently asking for the results as often as needed, or asking for a clear date of when the results will be available, may be a wise option.
best wishes,
Fr. Pat