Which of the following is primarily used for transfusion medicine testing?

The pink tube is primarily used for transfusion medicine testing because it contains EDTA, an anticoagulant that is crucial for preserving blood samples for various immunohematology tests. These tests include blood typing and antibody screening, which are essential prior to blood transfusions to ensure compatibility between donor and recipient blood. The pink tube is specifically designated for blood bank specimens, supporting the accuracy and reliability of transfusion medicine procedures.

Each of the other tubes serves different purposes: the purple tube is typically used for complete blood counts and other hematological tests; the green tube, which contains heparin, is used for chemistry tests and some specific assays; and the light blue tube, containing sodium citrate, is mainly utilized for coagulation studies. Thus, their applications differ significantly from the specific requirements of transfusion medicine testing.