Table 7.

Summary of key pre-analytical recommendations about freezing and thawing

Freezing and thawing	Do not perform PT, aPTT and factor VIII tests from frozen samples.
	Centrifuge samples that cannot be tested within 4 h and frozen the plasma aliquot.
	Use rapid freezing technique (liquid nitrogen).
	Store samples at −70 °C (or below) rather than −20 °C.
	Plasma samples frozen at minus 20 °C remain stable for 2 weeks.
	Plasma frozen at minus 80 °C remains stable for 6 – 18 months dependent on the parameter.
	Do not re-freeze samples (but prepare a sufficient number of aliquots).
	Thaw samples rapidly at 37 °C (to prevent denaturing fibrinogen) at least 5 min in a water bath at 37 °C and not at room temperature, on a bench or in a microwave oven. Test immediately.
	After thawing, mix the sample gently to resuspend any cryoprecipitate. Do not vortex or shake.
	Do not re-frozen samples.