|Year : 2015 | Volume
| Issue : 1 | Page : 20-22
Acid phosphatase activity and sperm morphological changes in vaginal swab samples collected at various post coital intervals: A study
Saka Koko Maring1, Thounaojam Meera1, Huidrom Nabachandra1, David Gangte2
1 Department of Forensic Medicine, Regional Institute of Medical Sciences, Imphal, Manipur, India
2 Department of Biochemistry, Regional Institute of Medical Sciences, Imphal, Manipur, India
|Date of Web Publication||17-Jun-2015|
Dr. Thounaojam Meera
Department of Forensic Medicine, Regional Institute of Medical Sciences, Imphal - 795 004, Manipur
Source of Support: None, Conflict of Interest: None
Background: In sexual assault investigation, the scientific proof of the alleged crime as well as determination of the time of assault is crucial. Materials and Methods: The study was carried out by analyzing 157 vaginal swab samples collected from women attending a tertiary health care teaching hospital, at Imphal and as well from the sexual assault cases, which were brought for medicolegal examination in the same hospital at different post coital intervals (PCIs). The samples were studied for sperm morphology and acid phosphatase (ACP) levels at different PCI were established. The findings were recorded and statistically analyzed. Results: Complete sperm was seen up to 16 hours and sperm heads were observed up to a PCI of 63 hours. The mean ACP level of >30 King-Armstrong Units (KAU) was observed in PCI of 1 day and >25 KAU in PCI of 2 days. The level of ACP showed more or less a gradual fall with respect to time with significant changes within 3 days. Conclusion: It may be concluded that an estimate of the timing of sexual assault may be given especially within 3 days of the assault, thereby emphasizing the importance of early reporting of such crimes.
Keywords: Acid phosphatase (ACP), Post coital interval (PCI), Sperm, Sexual assault
|How to cite this article:|
Maring SK, Meera T, Nabachandra H, Gangte D. Acid phosphatase activity and sperm morphological changes in vaginal swab samples collected at various post coital intervals: A study. J Med Soc 2015;29:20-2
|How to cite this URL:|
Maring SK, Meera T, Nabachandra H, Gangte D. Acid phosphatase activity and sperm morphological changes in vaginal swab samples collected at various post coital intervals: A study. J Med Soc [serial online] 2015 [cited 2020 Jul 12];29:20-2. Available from: http://www.jmedsoc.org/text.asp?2015/29/1/20/158924
| Introduction|| |
Sexual offences are usually hidden crimes and sometimes history of these crimes may be vague. The scientific proof of the alleged crime as well as the determination of the time of assault is crucial in sexual crime investigation. It is a known fact that finding of spermatozoa in vaginal swab of a victim is a conclusive proof of recent sexual intercourse; however, in case of an azoospermic or a vasectomized assailant, this crucial marker may not be seen. The enzyme acid phosphatase (ACP) in human seminal fluid is a dimeric glycoprotein and is synthesized by the epithelial cells that line the ductal elements within the prostate and elaborated into seminal fluid. The prostatic secretion element of seminal fluid contains 500 to 1000 times greater ACP than any other body fluid.  Since this enzyme is present in significantly high concentration in the semen, it may provide useful information in the investigation of sexual crime. An ACP activity of 25 KAU/mm of extract from an area of approximately 1 sq. cm. is considered positive for seminal stains, considering the dilution factor when making the final calculations.  The present study aims to find out the actual occurrence of the sexual assault with special emphasis on the timing of the alleged crime through these two markers.
| Materials and Methods|| |
The study was carried out by analyzing 157 vaginal swab samples collected from women attending a tertiary health care teaching hospital, at Imphal and as well from the sexual assault cases, which were brought for medicolegal examination in the same hospital at different post coital intervals (PCIs). For this study, only the cases who knew the exact timing of the last sexual intercourse were included. The study of spermatozoa morphology was done under light microscopy using Haematoxylin and eosin (H&E) stain, and the quantitative study of ACP was done by Modified King's Method using a kit manufactured by Crest Biosystems, Goa, India. The findings of the study were recorded and statistically analyzed.
| Results|| |
In the present study, complete sperms were mostly seen within 12 hours of last coitus. Sperm heads were seen up to a PCI of 63 hours, mostly in the post coital interval of 12-48 hours and no sperm head could be seen after 72 hours [Figure 1].
|Figure 1: Showing the persistence of sperm according to post coital interval|
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The mean ACP level showed a gradual fall with time after the last coitus. The maximum mean ACP level was seen on the first day i.e. 31.37 KAU whereas the least ACP level was seen at 3-4 months i.e. 7.4 KAU. The highest ACP value obtained in this study was 47.14 KAU in a case of PCI of 7.5 hours. The lowest ACP value i.e. 7.4 KAU was obtained in a case where the last coitus took place 3 months before the sample collection. The various mean ACP levels at different PCI are shown in [Figure 2], and the mean ACP level at various PCI along with sperm positivity is seen shown in [Figure 3]. The correlation co-efficient was calculated to be −0.429, which means that there was negative correlation between ACP level and PCI. The level of ACP was of significance till PCI day 3 (P < 0.05) in the post coital samples, and no statistically significant findings could be observed from PCI day 4 [Table 1].
|Figure 3: Scatter diagram showing ACP level at various PCI along with sperm positivity|
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|Table 1: Showing significance of ACP level in relation to various PCI (in days)|
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| Discussion|| |
The finding of spermatozoa is not essential to the proof of rape but such a finding indicates a completed act, and if spermatozoa are found in the vagina, it is a good evidence that sexual intercourse had taken place.  Following sexual intercourse, spermatozoa are found for seven to twelve hours in the vagina but exceptionally for 18-24 hours.  In the present study, complete spermatozoa were seen up to 16 hours and sperm heads were seen up to 63 hours and the average sperm survival period was 48 hours, which are in agreement with the findings of Wallace Haagens et al. 
In alleged sexual assault, a quantitative ACP determination may indicate not only the presence of seminal fluid but also the approximate time of coitus even in absence of spermatozoa.  In this study, out of the 157 cases studied, the mean ACP was 31.37 KAU in the PCI of 1 day and 26.62 KAU in the PCI of 2 days. This may be favorably compared with the findings of McCloskey et al.,  where 100% of the specimens above 25 KAU were taken within 48 hours of intercourse and 85.7% within 24 hours. Similar findings were observed by Lantz and Eisenberg.  The mean ACP level showed more or less a gradual fall with respect to post coital interval. This is in agreement with the findings of Findley  and Schumann et al.  It is a known fact that ACP is an enzyme, which is not unique to the prostate and can be found in other biological fluids including vaginal secretions. In a study by Lantz and Eisenberg,  it was observed that vaginal ACP activity in non-coital women is less than 10 U/litre, and in recently post-coital women is more than 50 U/litre. In another study by Kaye,  it was observed that less than 5 KAU of ACP/ml was found in substances viz. vaginal fluids, urine, faeces, blood, saliva. However, it is worthwhile to mention here that a low ACP level does not rule out the possibility of recent coitus, as it may be lower if the woman was menstruating, or had douched or used some suppository preparation or has certain pathologies correlating with ACP activity. 
| Conclusion|| |
An elevated level of the enzyme ACP is compatible with recent coitus; but the finding of spermatozoa in vaginal fluid is usually considered the diagnostic indicator for semen. Nonetheless, in sexual assault case workups, spermatozoa and ACP are excellent markers of recent coitus. An estimate of the timing may be given especially within 3 days of the crime, thereby emphasizing the importance of early reporting of such crimes.
| References|| |
Kaye S. Acid phosphatase test for identification of seminal stains. J Lab Clin Med 1949;34:728-32.
Sharpe N. The significance of spermatozoa in victims of sexual offences. Can Med Assoc J 1963;89:513-4.
Wallace Haagens MJ, Duffy BJ Jr, Holtrop HR. Recovery of spermatozoa from human vaginal washings. Fertil Steril 1975;26:175-9.
Findley TP. Quantitation of vaginal acid phosphatase and its relationship to time of coitus. Am J Clin Pathol. 1977;68:238-42.
McCloskey KL, Muscillo GC, Noordeweir B. Prostatic acid phosphatase activity in the post coital vagina. J Forensic Sci 1975;20:630-6.
Lantz RK, Eisenberg RB. Preservation of acid phosphatase activity in medicolegal specimen. Clin Chem 1978;24:486-8.
Schumann GB, Badawy S, Peglaw A, Henry JB. Prostatic acid phosphatase; current assessment in vaginal fluid of alleged rape victims. Am J Clin Pathol 1976;66:944-52.
[Figure 1], [Figure 2], [Figure 3]