Determination of the age of bruises using a bilirubinometer.

The dating of bruises can be of crucial interest in clinical forensic medicine, but the macroscopic or photographic evaluation of a bruise has not been regarded as reliable. Several methods have thus been regularly evaluated for this purpose, with reflectance spectrometry yielding promising results. The objective of this study is to evaluate the value of a bilirubinometer as a tool for dating bruises on living victims. A clinical follow-up was carried out on patients presenting a bruise with a known onset. Using a bilirubinometer, we obtained daily measurements of the bruise (bili-bruise) and of healthy skin (bili-skin). Potential confounding factors were collected: age, sex, body mass index, trauma mechanism and Fitzpatrick skin phototype. We followed 20 patients for a total of 88 measurements of bruises. Bili-skin values showed significant differences according to skin phototype. Differences between the bili-bruise and bili-skin values (Δ-bili) followed an increase phase, peaking between 3 and 5 days, and then there was a decrease phase. No significant Δ-bili value differences were observed based on the suspected confounding factors. Our results are in favour of a peak Δ-bili value generally at day 4 or 5 post-trauma. Notably, decreasing values were not observed before day 3. Decreasing Δ-bili values would then indicate a bruise resulting from an injury formed at least 3 days before the first measurement. Complementary work confirming such data would enable improvement of the performance of bruise dating in forensic medicine.
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