Evaluating the Reliability of Dipstick Drug Screens on Vitreous and Postmortem Blood as a Triage Modality in Forensic Pathology

Abstract

Dipstick drug screens are cheap, easy to use, and quick presumptive tests to detect common drugs of abuse. Dipsticks are designed for drug detection in urine. There is no literature regarding their potential use on fluids different from urine. The study aimed to determine the performance of dipstick screening tests on postmortem vitreous and blood specimens compared to urine dipsticks and final confirmatory toxicology analyses on blood. The study population included cases in which a complete toxicology analysis was performed. Each subject was screened for three substances: cocaine, fentanyl, and opiates. Dipstick results were checked by visual inspection. Results were compared with urine screening tests and quantitative, confirmatory toxicological analyses by gas chromatography/mass spectrometry on postmortem blood samples as the gold standards for screening and confirmatory analysis, respectively. There was a high number of false-negative results for opiates. Cocaine dipsticks in blood showed the highest reliability. Fentanyl dipsticks in vitreous showed a high number of false-negative results. Both vitreous and blood dipstick screening tests for all substances performed well on negative cases. When both blood and vitreous screening tests are negative, the chance that the confirmatory toxicology analysis will be positive is very low.