Haemolysis can be caused by:
1. Mixing additive tubes too vigorously or using rough handling during transport.
2. Drawing blood from a vein that has a hematoma.
3. Pulling back the plunger on a syringe too quickly.
4. Using a needle with too small of a bore for the venipuncture.
5. Using too large a tube when using a small diameter butterfly needle.
6. Frothing of the blood caused by improper fit of the needle on a syringe.
7. Forcing the blood from a syringe into an evacuated tube.
8. Excessive fist clinching.
9. Leaving the tourniquet on for longer than one minute.
Thanks to Kak Asmarani for the information about the phenomena.