Here is the situation: You were arrested for DUI and submitted to blood testing, the sample came back above .08 but the volume of blood in the tube is below the normal quantity (typically 10 ml). The question becomes is this a sign of something wrong?

Possibly, you see the blood tubes used in DWI testing will contain a vacuum that will cause the vial to fill to 10 ml if collected properly. So, when the tube is shown to have less than 10 ml it creates a situation that needs further investigation.

Some possible issues are a leak in the tube stopper which would have caused the vial to lose vacuum. This could cause contamination of the vial. Once a blood vial is contaminated there is a likelihood of fermentation and endogenous production of alcohol inside the tube. If the contents of the tube are contaminated by outside air there is a chance the tube now contains bacteria (candida albicans) which are everywhere. Alcohol is created when bacteria is nourished by sugar (contained within the blood). The bacteria eat the sugar and excrete alcohol.

If the reason that the tube didn’t fill all the way is that it lost some of its vacuum, then whatever was in the air got into the tube at the time it lost vacuum. It is no longer sterile, and if there was alcohol in the air when the tube lost vacuum, it is now in the tube, and will show up in the test result. In other words, it won’t give you a reliable test result, because we can’t say the test result reflects what was in your client’s blood when the sample was drawn. So if the person who drew the blood says that they did everything correctly, attempted to draw a full tube of blood, and don’t know why it didn’t fill all the way, any test result from the tube is unreliable.

Another problem concerning low volume blood tubes is the increased likelihood of higher concentrations of sodium fluoride and potassium oxalate in the vial resulting in a “salting out” effect of the sample. The increased concentrations create a higher level of analytes in the headspace sample.

What about situations where the phlebotomist intentionally collects less than 10 ml in the vial?

The evidentiary blood sample vials are commonly designed to hold 10 ml. Since they are pre-loaded with 2 chemicals in the form of powder inside the tube from the manufacturer – potassium oxalate and sodium fluoride, and the amounts of each should be tightly controlled (although this has been, on occasion, called into question).

Failure to put the right amount of blood into the tube screws up the blood:powder ratio which has implications at the lab. But it also signals that there was a procedural problem with the blood draw itself. That has implications for defense based on Acceptable Medical Practice (AMP) challenges.

In any event, anytime a blood tube contains less than 10 ml of blood it is cause for concern. California DUI Attorney Matthew Ruff has nearly 30 years experience fighting drunk driving cases. If you have a pending case and are seeking a defense lawyer who knows the science and laws to fight a driving under the influence charge, contact Matt for a consultation regarding the possible defenses in your case.