Abstract
Introduction
Studies on the ageing of bruises have been reported on Caucasians or individuals of fair ethnicity. This study focuses on bruise changes in dark-skinned individuals using tristimulus colorimetry for forensic analysis in such individuals.
Methods
Eighteen subjects of South Indian or Sri-Lankan ethnicity were recruited. Subjects were bruised using a vacuum pump and then daily colour measurements were taken of the bruise using a tristimulus colorimeter. The L*a*b* readings were recorded of a control area and of the bruise until it disappeared. Two Caucasians were used for comparison.
Results
This study showed that, using colorimetry, bruises on dark-skinned individuals can be measured and analysed even if the bruises are unclear visually. As the bruise is beneath the skin, the colour difference ΔL*, Δa* and Δb* were calculated. All values showed a trend, indicating that the L*a*b* measuring technique is a reliable method to analyse bruises on dark-skinned individuals. Comparisons of Asian subjects and Caucasian subjects were performed. The largest difference was seen in the b* value. Statistical analysis showed that ΔL* colour difference was the most consistent (95% CI −4.05 to −2.49) showing a significant difference between days 1–4 and 5–8.
Conclusion
Objective assessment of bruises on dark-skinned individuals using the L*a*b* method of measuring gave reproducible results. Furthermore, the study showed that the yellowing of a bruise cannot be seen or measured with a tristimulus colorimeter on dark-skinned individuals due to the pigmentation of the skin. With further studies and more subjects, the age of bruises could potentially be assessed for use in forensic analysis.
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