Platelet transfusion

Treatment for bleeding irregularities

Platelet transfusion, also known as platelet concentrate, is used to prevent or treat bleeding in people with either a low platelet count or poor platelet function. Unmatched platelets, however, are often used due to the unavailability of matched platelets. They are given by injection into a vein. Side effects can include allergic reactions such as anaphylaxis, infection, and lung injury. It is on the World Health Organization's List of Essential Medicines. Some versions of platelets have had the white blood cells partially removed or been gamma irradiated which have specific benefits for certain populations.

International guidelines recommend that platelets transfusions are given to people with reversible bone marrow failure to reduce the risk of spontaneous bleeding when the platelet count is less than 10 x 109/L. If the person is well using a higher platelet count threshold does not reduce the risk of bleeding further.

A review in people with blood cancers receiving intensive chemotherapy or a stem cell transplant found that overall giving platelet transfusions when the platelet count is less than 10 x 109/L reduced the number of bleeding events and days with significant bleeding. However, this benefit was only seen in certain patient groups, and people undergoing an autologous stem cell transplant derived no obvious benefit. Multiple guidelines recommend prophylactic platelet transfusions are not used routinely in people with chronic bone marrow failure, and instead an individualised approach should be taken. There is no evidence that this reduce the risk of bleeding, but there is evidence that they increase the risk of harm due to the platelet transfusion (increased risk of a transfusion reaction including anaphylaxis). Higher platelet transfusion thresholds have been used in premature neonates, but this has been based on limited evidence. There is now evidence that using a high platelet count threshold (50 x 109/L) increases the risk of death or bleeding compared to a lower platelet count threshold (25 x 109/L) in premature neonates.

A review in people with blood cancers compared different platelet transfusion doses. This review found no difference in the number of people who had clinically significant bleeding between platelet transfusions that contained a small number of platelets (low dose – 1.1 x 1011/m2) and those that contained an intermediate number of platelets (intermediate dose – 2.2 x 1011/m2). This review also found no difference in the number of people who had clinically significant bleeding between platelet transfusions that contained a small number of platelets and those that contained a large number of platelets (high dose – 4.4 x 1011/m2).

In people with a low platelet count, prophylactic platelet transfusions do not need to be given prior to procedures that have a low risk of causing bleeding. Guidelines recommend that it is safe to perform central venous catheter insertion when the platelet count is 20 x 109/L or above. Platelet transfusion thresholds for more major procedures are based on expert opinion alone. Guidelines recommend a threshold of 50 x 109/L for major surgery and a threshold of 100 x 109/L for surgery on the brain or the back of the eye. Much of the remainder are used in general medicine, cardiac surgery and in intensive care. An ageing population, an increase in the number of people with blood cancer, and changes to the management of these cancers are likely the major reasons for the rise in demand for platelets.

Platelet transfusions came into medical use in the 1950s and 1960s.

Platelets can be produced either from whole blood donations or by apheresis. They can be treated with ultraviolet light which decreases the risk of transmission of certain infections. They can be gamma irradiated which have specific benefits for certain populations (those at risk of transfusion associated graft versus host disease).