help with blood tubes!!!

[farmergal13]

Does anyone know the phrases to help remember which tube should be used first??? any help will be appreciated!! thanks in advance!

[Jokerhill]

You can draw a red or red/black tube before a blue tube to use as a waist as there are not any additives in these that can contaminate the coag test. The reason that you want to draw a waste tube first is that the skin and tissue that the needle passes through has thrombin in it that is a clotting factor. Thrombin will start the clotting process in the blue tube if it is drawn first, causing a prolonged pt/ptt test result. It prolongs the test because it binds/uses up the clotting factors prior to the test being run. PT/PTT test are a timed test to see how long it takes to for a clot in the intrensic and extrensic to form. You can use the red top tube for other testing if needed. An extra blue top if drawn first is just a waste and I would not want you to send it in for testing in error and toss out the second tube. But don,t use any other tubes first. As for blood cultures there are many other considerations to take into account and can be the most screwed up.