What are two common anticoagulants found in blood collection tubes?

The choice of EDTA (ethylenediaminetetraacetic acid) and sodium citrate as common anticoagulants in blood collection tubes is correct due to their distinct mechanisms and applications in laboratory settings.

EDTA works by chelating calcium ions, which are essential for the coagulation cascade. By binding these ions, EDTA effectively prevents blood from clotting, making it particularly useful in hematological analyses where accurate cell counting and morphology are crucial. It's commonly found in tubes meant for complete blood counts and other tests requiring whole blood.

Sodium citrate, on the other hand, also acts by binding calcium ions but is predominantly used in coagulation studies. It creates a reversible anticoagulant effect, allowing for assessment of the coagulation pathways without significantly interfering with the tests, making it invaluable for tests such as prothrombin time (PT) and activated partial thromboplastin time (aPTT).

The other options involve anticoagulants that either do not commonly coexist in blood collection practices or are less frequently used in standard laboratory tests. For instance, citrate and oxalate are less commonly paired in this context, and while heparin is indeed an anticoagulant, the combination with EDTA is not as typical for