Assessment of postmortem urine fentanyl detection by autopsy dipstick testing in accidental overdose deaths.

This article focuses on evaluating the effectiveness of commercially available urine dipstick tests in detecting fentanyl and norfentanyl in postmortem cases of fentanyl-related accidental overdose deaths. Reviewing 1,550 cases from San Francisco, the study found that 5% of fentanyl-related deaths had fentanyl or norfentanyl detected in blood but not in urine, indicating potential false negatives if relying solely on urine testing. Analysis of urine dipstick test cut-off levels revealed that higher cut-offs substantially increase false-negative rates, with up to 61% of cases missed at the highest thresholds. The findings suggest that urine dipstick tests, due to their sensitivity limitations and potential cross-reactivity, should not be used as the sole screening tool to determine the need for comprehensive toxicology testing or to establish cause of death in fentanyl overdose investigations.