Sexual assault patterns - clinical examination of victims in a twenty-five years period.

Rape is unlawful sexual intercourse of a female by a male without her consent. Examination of victims exposed to sexual assault to provide evidence of violence and sexual intercourse is well known in the clinical forensic medicine and has been performed at our institute since 1928. The society has undergone many changes since then and some of these changes might influence the sexual assault patterns. It has been assumed that the victims age has decreased over the years and that anal and/or oral penetration has become more frequent. Furthermore it has been assumed that there has been an increase cases with more than one perpetrator

The purpose of the present study is to establish whether these parameters have changed over the last twenty-five years.

Material and methods

The material comprises medico-legal reports of about 1029 alleged sexual assault cases examined at the Institute of Forensic Medicine in Copenhagen from 1975 to 1999.

Cases of vaginal and/or anal and/or oral penile penetration or attempted penile penetration were included. Cases without attempted penile penetration, cases in which the victims were unable to give any information about the assaults and cases of false reports were excluded.

The present study comprises 952 cases ranging from 17 cases in 1990 to 71 cases in 1999. The material was divided into 5 five-years periods, including from 156 cases in 1990-94 to 247 cases in 1995-99, and for each period the number and site of penile penetration or attempted penile penetration was registered. The victims' mean age were calculated and the victims were divided in 3 age-groups: under 20 years, from 20 to 40 years and over 40 years. The number of perpetrators were divided in 2 groups, cases with one perpetrator and cases with more than one perpetrator.

The results are shown in table 1 to 4.

Results

Penile penetration in the vagina is reported in over 90% of the cases through the twenty-five years period. In the same period anal penetration increased from 6% in 1975-1979 to 16% in 1995-99, and oral penetration increased from 16% in 1975-79 to 24% in 1995-99 (Table 1).

The victims mean age increased from 25 years in the beginning of the period to 27 years in the end of the period (Table 2). The percentage of younger victims (<20 years) are, after a decrease in the middle of the period, again increasing to about 30% (Table 3). The percentage of older victims increased through the period from 9% to 15%. Cases with more than one perpetrator occurred in about 10% in 1975 to 1984, since then the occurrence has decreased to 6% at the end of the period (Table 4).

Table 1. The site of penile penetration or attempted penile penetration.

Table 2. The victims' mean age.

Table 3. The victims' age in three groups.

Table 4. Cases with more than one perpetrator.

Conclusion

As assumed there has been a change in the penile penetration or attempted penile penetration pattern in the medico-legal examinations. Nowadays anal penetration is intended in every sixth case and oral penetration in every fourth case of rape or attempted rape. This is important to bear in mind for the medico-legal examiner in order to make a thorough examination of the victim.

The mean age of the victims seems to be stable, but there has been an increasing dispersion of the victims age to about 30% younger victims (<20?years) and 15% older victims (>40 years).This might have influence on prevention, examination and treatment of sexual assault cases.

Multiple perpetrator cases (mass-rape) has been an issue of high interest in the media for the last years. It seems that after a occurrence of 10% in the beginning of the period, the occurrence has stabilised on 6% in the last period.

Further analyses of the results have to include perpetrator profiles and socio-demographic data of the victims.

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