Since few studies have examined the influence of blood-specimen collection and shipping procedures on differences in drug concentrations detected in the specimen, this study examined three different peripheral-blood specimen collection/shipping procedures in order to determine whether significant differences in drug concentration in the blood specimen could be detected.
Although no statistically different drug concentrations in the blood specimens were found among the three collection/shipping methods for most drugs, several subjects had one or two specimens that were negative. The study concludes that the findings indicate the potential for misinterpretation in the detection of drug concentrations in peripheral-blood specimens due to how the specimen was collected and/or shipped to the reference laboratory. A false negative result was noted for certain drugs in specimens obtained from the inguinal region and iliac vein. The specimens were frozen, shipped on dry ice, and held in storage for a varying amount of time. False negative toxicological results will, in most cases, dramatically impact the certification of death. The findings also suggest postmortem re-distribution (PMR) within the peripheral compartment. The research team advises that the number of specimens obtained during the routine autopsy should not be confined to only one site. Rather, multiple samples should be obtained from different sites that include peripheral and central compartments; and different specimen types should be collected, including urine, tissue such as the liver, and possibly vitreous. The acquisition of peripheral blood using the "blind" stick of the femoral vein of the inguinal region seems to be a valid and preferred specimen. The research team also advises that pathologists and toxicologists should use caution when interpreting peripheral blood drug concentration; it is best to refrain from making a diagnosis based solely on the drug level. Implications are drawn for further research. 4 tables, 39 references, and research dissemination information