Critical Analysis of Laboratory Testing Methodologies When Interpreting Conflicting Results at Autopsy

Toxicological analysis is an important diagnostic component of a postmortem examination and may involve both antemortem and postmortem specimens. Here, we present a case in which an antemortem specimen, when reanalyzed in the forensic toxicology laboratory, resulted in values that contradicted the reported values from the medical record and required further investigation. This case involves a 51-year-old man decedent with a medical history of chronic alcohol abuse. His antemortem urine drug screen, performed upon admission to an emergency department, was negative. His serum blood alcohol level at presentation was reported as 0.960 g/dL and, repeated 4 hours later, was 0.500 g/dL with a comment indicating that there was significant lipemia interfering with the results. At autopsy, the antemortem blood sample collected from the hospital, postmortem blood, and vitreous humor samples were analyzed and all 3 samples were found to be negative for ethanol. The hospital laboratory used an enzymatic assay for ethanol detection, which is known to be impacted by lipemia, and the forensic laboratory used head-space gas chromatography, which is not impacted by lipemia. This highlights the need to critically analyze laboratory testing methodologies when interpreting conflicting results at autopsy.