Why won't the doctor order a blood transfusion to boost low platelets?

A fellow caregiver asked...

My father, who's undergoing chemotherapy for colon cancer, has a very low platelet count and we're worried about bleeding. Why won't his doctor just give him a transfusion of platelets?

Expert Answer

Andrew Putnam, M.D. is a Palliative Care physician at Smilow Cancer Center at Yale New Haven Hospital and Yale University.

Most doctors only give platelet transfusions in cases where the patient is actively bleeding and the blood won't clot. The reason is that this treatment is of limited benefit and only lasts a very short time. The problem has to do with the life of the cells. Unlike red blood cells, which on average live about 120 days, platelets on average live only eight days. When you get a transfusion of blood from someone else, some of those cells are very old and some are brand-new, so you have to assume that the average platelet's going to last only four days. Then, when you figure in that they've been taken out of one body and put in another, and they've been frozen or stored, the estimate for the average lifetime of each platelet is even less than that—maybe just one to two days. So if your father is not actively bleeding, then the platelets may all die off before there's any real benefit. Your father would need another transfusion every few days to see any long-lasting effect. That's why his doctor is more likely to have him wait (and be careful not to cut himself) and see if his platelet count rises naturally.