Blood Test with tourniquet left on

[Gingernut44]

Hi all, a couple of weeks back I read on one thread the skewing/difference it made to blood test results when the Nurse/Phlebotomist left the tourniquet on your arm during the entire blood test. Unfortunately, I can't remember who made the post so, if anyone knows the answer, can you please let me know. TIA

[thyr01d]

I can't see how that could make a difference so will be interested to see what replies you receive.

[Gingernut44 in reply to thyr01d]

Me too

[Saltwater]

I know a little about this but not a lot.... If I recall correctly, leaving a tourniquet on for a while is fine while you have the needle in but the tourniquet should be removed before the needle is withdrawn and within a set time, otherwise it causes hemoconcentration which can affect the blood test results, eg, it causes a decrease in plasma and can increase things like red blood count. Sometimes it is hard to find a vein and collect a sample in which case, the tourniquet should be removed after one minute and the arm rested for a couple of minutes before trying again to allow the blood to return to a base rate. It used to be recommended that patients pump their fists before collecting a sample but this has a similar effect on the blood and encourages hemoconcentration. The muscle action of pumping the fist also increases minerals in the blood collected like potassium and calcium ions and can make the results differ quite dramatically that it can lead to false or no diagnosis.....but don't quote me!

[Gingernut44 in reply to Saltwater]

Thanks for that - the Nurse who took my last bloods left the tourniquet on for the whole time, only taking it off after she had finished filling the phials. At the previous blood test with a different Nurse she took the tourniquet off as soon as the blood was flowing, so I'm still none the wiser

[Saltwater in reply to Gingernut44]

Well, the guidelines are to not leave the tourniquet on for too long (to avoid hemoconcentration) and to take the tourniquet off as soon as blood flow is established and before withdrawing the needle (to prevent blood leaking into the surrounding tissue). As I say if the tourniquet is on too long, then the blood plasma can be decreased in the sample, 'concentrating' the blood. Plasma is mostly water but also made up of things like glucose, antibodies, enzymes and hormones, so if they take the test with the tourniquet having been on too long, then it can mean the blood does not reflect the base level of these constituents and your sample may be somewhat inaccurate as the amount of plasma (and the components which make it up) in a concentrated sample are reduced.

Hope this helps, but please don't worry about it. Have a nice evening.

[Gingernut44 in reply to Saltwater]

Many thanks for that Saltwater and you have a good evening also

[thyr01d in reply to Saltwater]

How interesting Saltwater