Sexual Assault

Alternate Light Sources: Part 1 (Skin Stains and Fluids)

The issue of Wood’s Lamps and other alternate light sources (ALS) in sexual assault medical forensic exams came up this week and it got me thinking about how often we do things because we were taught we should, and not because they’ve been shown to be particularly useful or effective. So I thought I’d take a few minutes to highlight the literature out there on ALS in the detection of semen on the bodies of sexual assault patients.

The general gist of the literature is that Wood’s Lamps are ineffective for consistently identifying semen in the medical forensic exam; other types of ALS seem to be more effective. That being said, being able to document the presence of a glowing substance (since many things fluoresce under ALS) may still be of limited value for the forensic healthcare professional. You can check out the following articles for research and information on the subject. Full-text articles were included where widely available online; otherwise, I have linked to abstracts. To be clear, the amount of research done on the subject is not overwhelming–there’s a definite need for more data as related to detection of semen on the human body with the tools generally found in clinical practice.

  1. An Alternate Light Source to Detect Semen
  2. Alternate Light Source Use in Forensic Nursing
  3. Comparison of laser and ultraviolet techniques used in the detection of body secretions
  4. Wood’s Lamp Utility in the Identification of Semen
  5. Sexual Abuse of Children: Detection of Semen on Skin
  6. The Use of an Alternative Light Source to Detect Semen in Clinical Forensic Medical Practice
  7. Fluorescent Identification of Biological and Other Stains on Skin by the Use of Alternate Light Sources
  8. Alternate light sources in sexual assault examinations: An evidence-based practice project
  9. Evaluation of anogenital injury using white and UV light among adult volunteers after consensual sexual intercourse

Please note, I am not directing you to abandon your existing protocols and stop using Wood’s Lamp and other forms of ALS. However, I would suggest you be able to articulate why you use them and understand their limitations. And keep in mind, I’m not addressing the use of ALS for the detection of bruising or other types of injury. We’ll tackle that one in another post…

If you have other references on this topic, please let me know in the comments!

3 replies on “Alternate Light Sources: Part 1 (Skin Stains and Fluids)”

You are so right!! I had a case, many years ago, that there was no fluorescence anywhere. I collected by instinct and routine. There was no DNA on the vulvar, vaginal, or anal swabs, but a sample I collected from the patient’s neck was positive for DNA. Since then I mostly used the ALS to entertain the patients I have them put on the goggles and we look at things. But I have not depended on the UV lights for anything.
The Wood’s Lamp clearly was never a dependable tool. Even now, I hear nurses say, on the witness stand,that the Wood’s Lamp/ALS finds semen and sperm. The multitude of other things that fluoresce seem to have been forgotten. It will be the skill and competency of the nurse that will provide excellent collection techniques; not the toys and tools.

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