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NCCLS has recommended specific order of draw for multiple tube collections to prevent cross contamination of additives. Governing policies of each health care facility differ regarding the order of draw for vacutainer tubes. Phlebotomy standards applying to full and part-time phlebotomists, medical assistants, or other health care providers and personnel with blood collection responsibilities are set by

The Clinical and Laboratory Standards Institute (CLSI)
The order of draw generally follows the following order:
First: Blood Cultures – SPS for sterile specimens for microbiology
Second: Citrate Tube – a single light blue top tube may be drawn if only a routine coagulation assay is ordered.

If both are drawn together, then specimens that require no additives (plain tubes) followed by tubes needed for coagulation studies (sodium citrate or heparin).
Third: Non additive tube (red top)
Fourth: gel separator tubes first, then EDTA, then oxalates and fluorides.
SST gel separator and clot activator tubes
Sodium heparin tubes with dark green top
PST (Gel Separator Tube with Heparin)
EDTA Tube
ACD (pale yellow top) containing acid citrate dextrose
Fluoride (glucose) Tube
In case of slow and difficult blood draw, following proper order of draw ensures that chemical additive from one tube is not contaminating the next tube , e. g. if EDTA tube is collected prior to heparin tube for electrolyte analysis, the potassium salt of EDTA will cause high potassium levels.
Serum separator tubes
Use of incorrect of additive or wrong amount of additive can cause adverse effects.

The substance being measured may react with the additive or additive may be chemically the same as the substance being measured. Some cellular constituents may be altered or enzyme reactions may be inhibited by the additives.
It therefore becomes important that proper handling of blood specimens is done after collection by venipuncture.

The use of serum gel tubes is done to process the specimen and obtain serum.

The gel tubes provide a physical barrier between the serum or plasma following centrifugation. Serum separator tubes contain a clot activator (silica particles) to facilitate clotting. Unstoppering of these tubes is not required to be done before centrifugation which prevents aerosol formation. A higher yield of serum with a shorter processing time and safety is obtained by SST tubes.
Processing blood for serum
Laboratory tests for sodium, potassium, calcium, phosphorous, acid and alkaline phosphatase, cholesterol, uric acid, and liver function tests etc. are done by using serum. Serology also uses serum for analysis.
The standard safety precautions should be used considering all specimens as infectious. To separate the serum or plasma from the remaining blood cells, the tube must be centrifuged as quickly as possible. This is especially important when potassium oxalate has been used as an anticoagulant because potassium oxalate shrinks the red blood cells and intracellular water diffuses into the plasma.
Labeling with patient's name, DOB, time of extraction and other required fields by the phlebotomist is done for the proper management of specimens, and this is ensured by phlebotomist certification. Phlebotomist's knowledge and skills in obtaining incident reports, proper storage and preservation of samples and correct distribution to required locations is facilitated by phlebotomy training schools. Phlebotomist's job also involves proper disposal of contaminated equipments.
Written by Phlebotomy Training specialist Dr Shahbaz A. Cheema, Course Director for Maxis Healthcare who run NHS Accredited Phlebotomy Training courses for medical and non medical practitioners. Learn the 3 Steps To Become a Phlebotomist

Articoolz.com > Venipuncture: Order Of Draw