Forensic integrity of blood alcohol sampling in the emergency department, Part I: Epidemiology and factors affecting turnaround time.

Introduction: Drink-driving remains a leading global cause of road traffic fatalities. In Italy, the determination of blood alcohol concentration (BAC) in injured drivers relies on coordination between law enforcement and emergency departments (ED) to ensure legally admissible evidence. Because ethanol undergoes continuous metabolic decay, any delay in blood sampling can lead to underestimated values or "pharmacokinetic false negatives". Materials and methods: A retrospective study was conducted throughout 2025 on 115 drivers admitted to a major university hospital following road accidents. Preanalytical turnaround time (TAT), categorized into intra-ED and extra-ED intervals, was assessed against variables like clinical severity (triage code), temporal patterns (duty shifts/weekends), and licensure status. Serum alcohol concentration (SAC) that is used to screen BAC was measured with the enzymatic methods. Results: The population was predominantly male (77.4%) with a median age of 36 years. While the median intra-ED TAT was 139 minutes and remained stable across various clinical and temporal factors, the overall preanalytical TAT (from accident to sampling) reached a median of 204 minutes. The only statistically significant association concerned SAC at ED admission with ED duty shift (P = 0.045), and with day of the week (P = 0.035). Conclusions: The observed TAT appears insensitive to environmental stressors, potentially indicating a "degraded" baseline performance. This study emphasizes that objective quality goals for TAT cannot rely solely on administrative averages. Instead, they must be grounded in a quantitative relationship between sampling delay and metabolic decay using pharmacokinetic models to mitigate the risk of forensic evidence loss.