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Interpretation of postmortem vaginal acid phosphatase determinations
D A Chiasson1, R Vigorito, Y S Lee
1Office of the Chief Medical Examiner, State of Maryland, Baltimore.
The American Journal of Forensic Medicine and Pathology
|September 1, 1994
Summary
Vaginal acid phosphatase (AP) levels can indicate sexual assault in homicide investigations. High AP levels (>400 U/L) strongly suggest semen presence, but lower levels require careful spermatozoa examination.
Area of Science:
- Forensic Science
- Biochemistry
- Gynecology
Background:
- Identifying sexual assault evidence is crucial in female homicide investigations.
- Vaginal acid phosphatase (AP) is a potential biomarker for semen presence.
Purpose of the Study:
- To correlate vaginal AP levels with spermatozoa presence in female homicide victims.
- To compare these findings with an age-matched control group.
Main Methods:
- Retrospective analysis of vaginal AP levels in 43 female homicide victims using sodium thymolphthalein substrate.
- Correlation with semiquantitative assessment of spermatozoa in vaginal smears.
- Comparison with a prospectively studied control group.
Main Results:
- AP levels varied significantly between homicide victims (0-6,000 U/L) and controls (1-726 U/L).
- AP levels ≥ 400 U/L were always associated with spermatozoa presence in both groups.
- Lower AP values (<100 U/L) were found in 18% of homicide victims and 3% of controls with spermatozoa present.
Conclusions:
- High vaginal AP levels are a strong indicator of semen, even in oligo- or aspermic cases.
- Low or intermediate AP levels do not exclude semen presence, necessitating a thorough spermatozoa search.
- Vaginal AP testing is a valuable tool in sexual assault investigations, complementing spermatozoa analysis.