| dc.description.abstract | Background: Previous population based prevalence studies have shown that 1 out of 10 women in Norway have been raped and that only 11 % of these undergo a medical examination. A recent report claim that only 10 % of Norwegian women who have been raped report the case to the police, and that as many as 75 - 80 % of the cases never reach the stage of prosecution. Meanwhile, studies show that the forensic clinical examination has a big impact on the proceedings of the cases, which emphasizes the importance of developing best practice routines for securing forensic evidence (such as biological traces and documenting injuries). The Sexual Assault Center (SAC) at St. Olavs Hospital has since the 1990’s offered a “clinical” spermatozoa examination in addition to the police’s forensic trace evidence swabs for patients contacting the hospital after sexual assault. These samples are analyzed for sperm cells at the cytology lab at St. Olavs Hospital (CYTLAB). In addition to this, from November 2015, samples from the patients contacting the Trondheim SAC have been analyzed for both seminal fluid, spermatozoa and DNA quantities at the Center of Forensic Genetics (RGS) in Tromsø (UiT).
The aim of this study was to describe and compare the test results from the different methods of detecting spermatozoa and semen in swabs collected from female patients contacting the Trondheim SAC. We also wanted to describe the results of the DNA quantification performed at the RGS in Tromsø. In addition, we wanted to examine whether certain characteristics of the patient, assailant, or assault were associated with positive spermatozoa findings in this clinical setting.
Methods: We conducted a retrospective, descriptive cross-sectional study based on data from the medical records of women ≥ 12 years of age given a medical examination including sperm testing at the Trondheim SAC, Norway, throughout 2012 - 2017. The samples were analyzed for spermatozoa using Papanicolaou (PAP) staining and were screened with conventional light microscopy at the CYTLAB in Trondheim during the entire study period. From October 2015, the samples were additionally analyzed for seminal fluid using RSIDTM-Semen, for spermatozoa using Sperm Hy-LiterTM, and by quantification of DNA using Quantifiler 1 Trio- kit, all performed at the Centre of Forensic Genetics, UiT. A total of 355 cases were included. Descriptive characteristics were reported by frequencies. Pearson’s x2-test, t-test and Mann- Whitney U-test was used for comparing assault characteristics and medico-legal factors by sperm test results. Statistical significance was assumed when p < 0.05. Multivariable logistic regression analysis was used for calculating odds ratios with corresponding confidence intervals (95 %).
Results: During the entire study period 355 samples were analyzed and in 118 samples (33.2 %) spermatozoa were detected. The majority of the patients were between the age of 12 and 24 years with a mean age of 24.6 years. Sperm Hy-Liter test by the RGS resulted in a higher detection rate of spermatozoa compared to conventional light microscopy by the CYTLAB. Out of the 51 samples where the Sperm Hy-Liter detected spermatozoa, 49 samples contained enough DNA to expect an informative DNA profile. It was significantly more likely to detect sperm cells when the time interval from assault to medical examination was ≤ 24 hours, if vaginal penile penetration, if ejaculation had occurred, and when a condom had not been used. Of the total 355 cases, 61 % were reported to the police, 54 % of the trace evidence kits were collected by the police, and in 26 % of the cases a SAC forensic medical report was requested by the police.
Conclusions: Investigations concerning presence of spermatozoa after sexual assault is often a subject that attracts a lot of attention in studies like ours. Although a positive sperm finding can prove that a sexual contact has occurred, it has been found to have little impact on the case proceedings since medico-legal evidence does not equal evidence of rape. Our study implies that the Sperm Hy-Liter staining is superior to conventional cytology for this purpose.
The routine of sending samples to the RGS for Sperm Hy-Liter analysis should therefore be continued. Focusing on best practice routines for collecting and detecting spermatozoa should continuously be an important issue for development and evaluation. Since a spermatozoa positive sample provides the possibility for creating a DNA profile of a suspect, our efforts and findings should be of major interest to the police and the legal system.
Keywords: Sexual assault, Sexual Assault Center, Sexual Assault Centre, Rape, Medico-legal examination, Trace evidence, Medico-legal findings, Semen, Spermatozoa, DNA detection, DNA profiling, DNA match | en_US |
