Blood and blood products are collected as whole blood from donors in various anticoagulants. The blood and blood products which are used for transfusion are whole blood, packed red blood cells (PRBCs), platelet concentrates, fresh frozen plasma (FFP), cryoprecipitate, and plasma derivatives. Plasma derivatives are also used for transfusion such as albumin, intravenous immunoglobulin, anti-thrombin, and coagulation factor concentrates. Plasma derivatives are generally collected from several donors and pooled together and infectious organisms are removed by treating.

Separation of blood components from whole blood:

Blood is collected as whole blood of 450 ml (one unit of blood) in various anticoagulants. The whole blood is then processed to produce blood various blood components mentioned above. Most commonly blood is transfused as whole blood. To get blood components, whole blood is first separated by slow centrifugation into PRBCs and platelet rich/concentrated plasma.

Generally adverse reactions of blood transfusion are (1) non immune mediated and (2) immune mediated. Fortunately the common adverse reactions that occurs after blood transfusion are mild and serious adverse reactions occur only rarely, if ever.

The blood transfusion may also be complicated by transmission of infectious agents, such as virus, bacteria, and other infectious agents. Fortunately the transmission of infectious agents is also rare, especially viral transmissions are becoming rarer due to pretransfusion screening of donor’s blood.

What are the non immune mediated adverse reactions that can occur?

The non immune mediated adverse reactions that can occur after transfusion of blood and blood components are volume overload, hypothermia (subnormal body temperature), electrolyte imbalance (mainly toxicity), iron overload, hypotensive reactions and immunomodulation etc.