Perhaps the nurse did not want to be too graphic in describing the procedure. Anyhow, how many needles being used–depends on how fast each needle tip dulls. The procedure is usually done by two persons, one stands on each side of the donor, both drilling into the the top portion of the hip bone (iliac crest). The marrow aspirate needle will become dull after a few sticks. With each stick, you would try to get 3-4 aspirates, pivot the needle to different directions from the same “hole” to get marrow from slightly different areas. You suck too much marrow from one spot, you get marrow diluted with peripheral blood. It is physically tiring for the operators, hence two persons usually, if more poeple are available, trade off when one’s arm wears out doing the drilling.
In all likelihood, when you are called to duty, all marrow stem cells may be harvested via peripheral stem cell collections, so don’t worry too much or rush to disenroll yourself from the marrow donor list. Like I said earlier, if you were to donate for yourself or your relative, the harvest would be done through peripheral methods, involving no more than IVs connected to pheresis machines similar to platelet donation.
I’ve done the harvesting procedure, never gone through the donating part.