Why does blood clot inside a syringe? What is the mechanism of it?
Due to chances of blood clotting before an injection is complete, all clinically-approved syringes are pre-coated with anticoagulants e.g. sodium citrate, heparin, etc., that are washed off in no more than a few injections.
Reasons and mechanisms of blood clotting
Clotting of blood is prevented by one of the following methods:
Chelation or binding of calcium.
Precipitation of calcium making it unavailable to the clotting process.
Inhibiting the formation of thronging which is needed to convert fibrinogen to fibrin in the coagulation process.