Evaluation of bladder wash for postmortem toxicological analysis: Comparison with urine in 50 forensic cases.

In postmortem toxicology, urine serves as a reference matrix for determining the circumstances of death. However, urine may be unavailable or unsuitable for analysis in certain forensic cases. In this context, bladder washing (BW) has recently been proposed as an alternative matrix, although supporting evidence remains limited. This study aimed to evaluate the reliability and forensic relevance of BW for postmortem toxicological investigations. Toxicological screening was performed using LC-PDA-QDa, LC-MS/MS, and LC-HRMS after liquid-liquid extraction in paired urine and BW samples from the same individuals. Data from 50 autopsy cases were analyzed to compare the performance of BW with urine in terms of analytes and metabolites detection. The cohort included 50 cases (80% male, mean age 42 years), with a mean postmortem interval of 1.2 days and a mean sampling delay of 2.98 days. A 95.7% concordance was observed between the two matrices, with 395 compounds detected in urine and 378 in BW, corresponding to 91 different xenobiotics. These findings demonstrate that BW can serve as a reliable and representative alternative when urine is unavailable, allowing a broad panel of substances to be detected using standard analytical workflow. Standardization of BW collection and analysis could enhance postmortem toxicological investigations and provide forensic practitioners with comprehensive toxicological information in challenging cases.