Blood Test

Where do those magic BAC numbers come from? Is there some scientist looking at my blood underneath a microscope? Are the numbers ever wrong? What outside factors can falsely increase a BAC?

The 3 main problems that occur with the blood process are; fermentation, coagulation, and hemolysis.  These will occur during the a) the collection process b) the storage process, and c) the testing process.



When the blood is not collected in a medically approved manner then that can lead to problems in trusting the final BAC result. It all starts in the collection environment. Was your blood drawn in a hospital setting or was it done in a dirty underground garage? Or worse, out on the side of the road with your arm flopped over the hood of a patrol car. Correct procedures require that the puncture site be properly clensed with a non alcohol based solution. The arm should be clensed in an outward circular motion and not in a back-and-forth wiping actions. The idea is to have any microbial germs moved away from the area where the needle with puncture the skin.

When your blood was collected was the vial 1/2 full? 3/4 full? Did the phlebotomist invert the vial 16 times? Did the phlebotomist collect more than one persons blood at a time? Did they mix up the blood vials?

Arterial or Vein? The phlebotomist is suppose to draw blood from a vein. In the event they miss the vein and draw blood from an underlying artery the end result will be a falsely higher BAC.

Blood Vial : In most blood draw the phlebotomist is using a Beckton Dickinson Vacutainer. This vial is 10ml, has a grey rubber top, and contains the chemical sodium fluoride and potassium oxalate. The soduim fluoride is suppose slow the naturally occurring fermentation process while the potassium oxalate is suppose to prevent coagulation of the blood. The occurrance of fermentation and coagulation can have a false negative effect on the final BAC result.

Fermentation: Fermentation is the self growth of alcohol within the blood vial. How do you make wine? You take a sugar (grape) and a bacteria (yeast) let it sit for a while and what do you have? wine. Well, what is happening in your blood vial? You take a sugar (glucose) and a common bacteria such as Candida Albicans, let it sit for as little as 10 to 20 hours at room temperature and what do you get? You will get an alcohol growth in the vial between .05 and .07 for someone that has normal glucose levels.


One of the first steps that the lab does with your blood once it reaches the lab is to put it in a refrigerator.  However, from the time that your blood is collected to the time that it reaches the lab it will most likely have been stored in a NON refrigerated evidence locker. I have seen some blood stored outside in metal evidence lockers for as long as 6 days before it was even picked up for transport. I have cross examined DOJ blood testers that have agreed that storage in a NON refrigerated evidence locker is NOT ideal.