Vitreous Humor Versus Peripheral Blood for Accurate Estimation of Antemortem Alcohol Levels: A Systematic Review of Postmortem Human Studies

Estimating antemortem blood alcohol concentration (BAC) after death is complicated by postmortem artifacts (endogenous ethanol formation, contamination, redistribution). Vitreous humor is anatomically protected and may resist these artifacts, offering a more stable matrix. The detection of ethyl glucuronide (EtG) and ethyl sulfate (EtS) can further distinguish true antemortem intake from postmortem production. Our objective is to evaluate the diagnostic reliability of vitreous ethanol concentration (VAC) as a surrogate for antemortem BAC, and to define contexts where vitreous testing adds forensic value. This review of postmortem human studies compared VAC with BAC, while adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines for systematic reviews. We searched PubMed, Scopus, Web of Science, and Google Scholar from July 2010 to July 2025, screened in duplicate, extracted data using a standardized form, and appraised study quality with a revised Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) tool for forensic accuracy. Given methodological and clinical heterogeneity (analytical techniques, postmortem interval (PMI), decomposition), we performed a structured narrative synthesis. Nine studies (Europe and Asia) met our inclusion criteria. Most used headspace gas chromatography with flame ionization detection (HS‑GC/FID) for ethanol; several incorporated liquid chromatography-tandem mass spectrometry (LC-MS/MS) for EtG/EtS. VAC and BAC were strongly correlated (r ≈ 0.89-0.97) under standardized sampling and shorter PMIs. Vitreous matrices showed greater resilience in cases with decomposition, long PMI, or suspected microbial ethanol formation. Studies measuring EtG/EtS indicated that combined ethanol-metabolite interpretation improves specificity for antemortem drinking and reduces false positives. Despite high correlation, individual BAC predictions from VAC had wide confidence/prediction intervals, underscoring the need for contextual, multi‑parameter interpretation. QUADAS‑2 suggested a low risk of bias in most domains across included studies. Meta‑analysis was not feasible due to heterogeneity. In conclusion, vitreous ethanol is a forensically robust adjunct or alternative to peripheral blood when BAC is unavailable or compromised, particularly with decomposition or suspected postmortem ethanol formation. Interpretation should pair VAC with EtG/EtS, femoral BAC (when available), PMI, and scene/autopsy data. Standardizing analytical protocols and validating calibrated prediction models across PMI and decomposition strata are priorities to reduce case‑level uncertainty.