Order of draw part 2

• Prevent contamination of blood specimens

  • Additive carryover

  • Tissue thromboplastin -affect coagulation tests

  • Microorganisms -invalidate blood culture results

Purpose of order of draw

1. Blood culture

2. Sodium citrate - light blue

3. Serum - red, gold

4. Heparin - green

5. EDTA - lavender, pink, white

6. Sodium fluroide/potassium oxalate (gray)

Order of draw

• Draw a second one, throw away the mistake

• Draw a few millimeters of blood in a discard tube

• Resume correct order of draw

What should you do if you realize that a tube has been drawn in the wrong order

carryover/cross-contamination

Transfer of additive from one tube to the next

• Blood in an additive tube touches the needle

• Blood is transferred from a syringe into tubes

Causes of carryover

EDTA

_______ in tubes has been the source of more carryover problems than any other additive

heparin

________ causes the least interference in tests other than coagulation tests because it also occurs in the blood naturally

Trace element

___________ tubes should be collected separately or if a syringe is used, change the transfer device before filling them

cobalt and chromium

A syringe must not be used to collect specimens for the trace elements _______ and _____ because the plunger tip may contain these elements

discard tube

Tube used to remove tissue fluid from the needle and is then thrown away

To protect the 9:1 blood-to-additive ratio and prevent air from displacing blood

Why must a discard tube always be used for a coagulation test when it is the first or only tube collected using a blood collection set

blood cultures

Detect microorganisms in the blood

• Require special site-cleaning measures to prevent contamination of the specimen by microorganisms normally on the skin

• Collected when sterility of the site is optimal

Why are blood cultures drawn first or separately?