20 Minute Whole Blood Clotting Test
The 20 Minute Whole Blood Clotting Test provides a simple method of testing for coagulopathy in the envenomed patient, in circumstances where more sophisticated haematology is unuvailable.
The equipment needed for the test consists of:
- Tourniquet
- Cotton wool or gauze pad
- Sterile syringe and needle
- Gloves
- Sharps disposal container
- Sterile (or clinically clean) 10ml (or similarly sized) bottle, such as a McCartney bottle
- Clock or watch
Following normal venepuncture procedure, take 20ml of venous blood from the patient and place in the bottle.
Replace the lid of the bottle.
Place the bottle in a safe location, where it is not likely to get bumped or knocked over. The location of the bottle should be as close to room temperature as conditions allow.
Wait twenty minutes for the blood to clot. During this time do not shake the bottle or disturb the contents in any way.
After twenty minutes, gently invert the bottle, observing the contents. From this procedure it should be evident whether or not the blood has clotted.
Clotted blood is a negative result, indicating that there is no coagulopathy present. Blood which remains unclotted after 20 minutes shows the presence of coagulopathy. This does not, however, indicate whether the cause is a procoagulant or anticoagulant.
Last updated: July 2005
