Postmortem alcohol analysis of the synovial fluid and its availability in medico-legal practices

Alcohol analyses using the synovial fluid of the knee joint (synovial alcohol concentration, SAC) as well as blood (BAC) and urine (UAC) were performed by the pulse heating-gas chromatographic method in 12 medico-legal autopsy cases. In 11 of the 12 cases, the regression analysis showed that BAC and UAC had a fairly linear relationship with SAC, and the average ratios of the BAC/SAC and UAC/SAC were 0.76 +/- 0.12 (range 0.60-0.94) and 1.03 +/- 0.11 (range 0.90-1.21), respectively. The measured BACs showed a difference of 11.8 +/- 9.4% (0.9-27.1%) when compared with the calculated BACs by means of the average BAC/SAC ratio. Between the measured UACs and the calculated UACs, there was an average difference of 7.9 +/- 6.0% (0.3-17.8%). The present study demonstrates that the synovial fluid is one of the available biological specimens for the prediction of BAC or UAC within a range in autopsy cases in which suitable blood and/or urine specimens cannot be obtained.