False Positives in Alcohol Testing After Severe Accidents

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Hello Doctor: My friend was involved in a serious car accident and unfortunately succumbed to his injuries at the scene.
When he was taken to the hospital, a blood test was conducted to check for alcohol levels, which returned a result of 49, approximately 0.24.
However, my friend did not consume any alcohol.
After researching online, I found that in cases of severe injuries from accidents, certain factors may elevate related substances, potentially leading to false-positive results.
I would like to ask if the fact that my friend was in a collision with a bus and suffered significant blood loss could contribute to a false positive.
Additionally, is it possible that contamination from alcohol swabs during the blood draw could lead to erroneous test results? I would appreciate your insights on this matter.
Thank you!

Mr. Zhang, 20~29 year old female. Ask Date: 2013/09/07

Dr. Liao Yaopan reply Family Medicine

Hello, regarding your inquiry, it is unlikely for there to be a situation of "creating something out of nothing" concerning blood alcohol concentration.
The impact of alcohol swabs should also be minimal.
Thank you for your message, and we appreciate your concern.
Changhua Hospital.

Reply Date: 2013/09/07

More Info

Understanding false positives in alcohol testing, especially in the context of severe accidents, is crucial for both legal and medical reasons. In your friend's case, where a significant car accident resulted in severe injuries and a reported blood alcohol concentration (BAC) of 0.24%, there are several factors to consider that could lead to a false positive result.

First, it is essential to understand that alcohol testing can yield false positives due to various physiological and procedural factors. In severe trauma cases, such as your friend's, the body undergoes significant stress, which can lead to the release of substances that may interfere with alcohol testing. For instance, the presence of certain metabolites or other compounds in the bloodstream due to trauma, shock, or even the administration of medications can sometimes mimic the effects of alcohol or lead to elevated readings on alcohol tests.

Moreover, in cases of severe hemorrhage, as you mentioned, the body's metabolic processes can be altered. The stress response to trauma can lead to the production of substances that may be misinterpreted as alcohol by some testing methods. Additionally, the presence of ethanol in the bloodstream can sometimes arise from the fermentation of glucose in the body, particularly in cases of severe injury or metabolic distress.

Regarding the concern about contamination from alcohol swabs used during blood collection, it is a valid point. If alcohol swabs are used to clean the skin before drawing blood, there is a potential risk of residual alcohol contaminating the blood sample. However, most laboratories are aware of this risk and take precautions to ensure that such contamination does not affect the results. Typically, blood samples are drawn after allowing sufficient time for the alcohol from the swab to evaporate. Nevertheless, if the swab was not allowed to dry properly, it could theoretically contribute to a false positive result.

In summary, while it is possible for your friend's BAC to be falsely elevated due to the trauma and associated physiological changes, or due to contamination from alcohol swabs, it is essential to conduct further investigations to clarify the situation. If there is a strong belief that your friend did not consume alcohol, it may be beneficial to request a more comprehensive toxicology screening or a retest using a different method to confirm the initial findings. Additionally, consulting with a forensic toxicologist or a medical professional specializing in trauma care may provide further insights into the potential causes of the elevated BAC in this context.

In conclusion, while false positives in alcohol testing can occur, especially in severe trauma cases, it is crucial to approach the situation with a thorough understanding of the possible factors at play. It is advisable to seek further medical and legal counsel to address the implications of the test results and to ensure that your friend's case is accurately represented.

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