Low Specificity of Alternate Light Source (ALS) in the Detection of Bruising
A double-blind case control study evaluating the use of alternate light sources (ALS) in the detection of bruises demonstrated low specificity for this practice (50% specificity on days 1, 7 and 14). There is currently no evidence based support for the use of ALS in this capacity, despite emerging practice in the forensic nursing community, specifically to evaluate cases of reported or suspected strangulation.
Expertise in Evaluating Appropriate Usage of ALS
ALS has been utilized as a method to detect potential forensic evidence. If an area of skin “lights up” using the tool, swabbing the area and submitting for laboratory analysis is proper current practice. It is widely established that many substances (makeup, lotion, perfume, etc..) and skin conditions will give a “false positive” fluorescence leading to high sensitivity (ALS detects bodily fluids and bruises) but low specificity (high false positive rate). Just as fluorescence alone is not diagnostic of bodily fluids, it is not diagnostic of bruising.
Research on the Use of Alternate Light Source (ALS) in the Detection of Bruising
Results from a double-blind case control study conducted to establish a baseline sensitivity and specificity for bruising have been analyzed, presented at a national academic meeting and will be submitted for publication shortly.