Predictive equation for post-mortem interval using spectrophotometric values of post-mortem lividity: A pilot study

Abstract

The colour of post-mortem lividity and control skin of 86 cadavers was measured spectrophotometrically to obtain L* (value), a* (chroma) and b* (hue) values. In addition, left heart blood (n = 58), right heart blood (n = 57) and blood from the femoral vein (n = 21) were measured. Using these data, we analysed the relationship between post-mortem lividity, control skin and blood colours. L* of post-mortem lividity (L*p) and control skin (L*c) were strongly correlated ( r = 0.64). a* and b* of post-mortem lividity (a*p and b*p) significantly increased with an increasing post-mortem interval (PMI) but r2 values were low (0.11 and 0.070, respectively). Predictive equations for post-mortem lividity colour (L*p, a*p and b*p) were developed using control skin colour (L*c, a*c and b*c) and autopsy findings for the first time. The predictive equation for L*p explained almost 65% of the observed L*p. We created predictive equations for PMI with and without blood colour values, and the most accurate equation, which did not use blood colour values, made it possible to estimate PMI within ± 10.29 h. Further study of these equations will help us to understand the factors that affect post-mortem lividity colour and increase the accuracy of equations for predicting post-mortem lividity colour and PMI.