A preserved postmortem blood specimen can develop a higher ethanol concentration during later testing. Quintas and colleagues reported an increase from 0.18 to 0.85 g/L in one specimen, with bacteria and yeast recovered on culture despite reported fluoride preservation and cold storage. The case demonstrates a possibility; it does not establish how often this occurs or the person’s blood ethanol concentration during life.
The specimen and its documented history
The report concerned a 55-year-old, 75-kg man who became unwell at home, suffered cardiac arrest and died despite advanced resuscitation. Autopsy 14 hours after death found coronary atherosclerosis and ischemic cardiomyopathy, supporting probable natural death from coronary heart disease. No signs of sepsis or underlying infection were identified.
Peripheral blood was collected from the common iliac veins into standard plastic tubes containing 100 mg sodium fluoride and 20 mg potassium oxalate. These are additive amounts, not a stated fluoride concentration in the filled specimen. The paper does not give a blood volume from which to calculate that concentration.
Samples were reportedly kept at 4°C until laboratory arrival five days later, then at −20°C for two months before toxicological analyses were completed. Only blood alcohol determination was requested and performed. The report should not be described as a comprehensive negative drug screen.
Serial determinations exposed the discrepancy
Initial ethanol was 0.18 g/L. A second aliquot analyzed eight hours later measured 0.26 g/L, exceeding the laboratory’s 6% repeatability limit. The discrepancy prompted further testing rather than averaging the two results into an apparently settled concentration.
The next two determinations, performed two days later and one hour apart, both measured 0.62 g/L. A later pair both measured 0.85 g/L, and seven subsequent determinations remained at that value. The abstract describes reaching 0.85 g/L three days later; the detailed results describe the final pair three days after the preceding pair. That timing discrepancy prevents treating the account as an exact daily production-rate experiment.
Between same-day determinations, the specimen was kept at 4°C; between testing on separate days, it was reportedly stored at −20°C. The repeated results document change during the analytical sequence, but do not provide continuous temperature monitoring or establish precisely when each increment formed.
Confirmation of ethanol did not establish its origin
The laboratory used headspace gas chromatography with flame-ionization detection and simultaneous injection onto two columns of different polarity. The authors assigned one column a qualitative role and the other confirmation and quantitative roles; n-propanol was the internal standard.
The laboratory protocol used 0.10 g/L as the positive threshold triggering additional validation testing. This should not be relabeled as a reported method detection limit or quantification limit. The paper does not provide a complete validation dataset for those limits. Accurate identification of ethanol in the vial also cannot determine whether it came from drinking, formation in the body after death or formation after collection.
Microbiology supported an explanation, with unresolved limits
Culture detected Escherichia coli, Enterococcus faecalis and Candida parapsilosis. The serial rise together with microbial recovery supported the authors’ interpretation of in-vitro ethanol production. Blood glucose measurements were unavailable, so substrate depletion as an explanation for the eventual plateau remained a hypothesis.
The source and timing of contamination were not established. The authors found no evident collection or storage protocol failure, but the report was not a controlled comparison of preservatives, organisms or temperatures. One case cannot estimate prevalence or prove that fluoride routinely fails.
What the case supports in a death investigation
Preserve every serial result, collection and storage record, chromatogram and reason for repeat testing. Neither the first nor final result automatically reconstructs the living person’s concentration, and a rise in the stored specimen does not prove that all detected ethanol was produced after death. The findings alone establish neither impairment nor alcohol as a cause of death.
For a separate problem involving blood collected during life, see hospital ethanol specimens in death investigations. An antemortem specimen and a later autopsy specimen require different interpretive questions.
Primary source
Quintas MJ, Costa P, Melo P, Castro A, Franco JM, Teixeira HM. Postmortem in vitro ethanol production—It could be more common than we think! Forensic Science International. 2017;274:113–116. doi:10.1016/j.forsciint.2016.12.040.
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