In a consensual sexual intercourse sample, differences existed in injury prevalence and frequency in black and white females. More importantly, these differences were explained more fully by variations in skin color than by race/ethnicity. We suggest that our findings are likely a result of problems with injury detection on dark skin. This finding is novel and important with respect both to clinical assessment and the decisions made within the criminal justice process. If replicated, it indicates that females with dark skin will not be as likely as females with light skin to have their injuries identified, documented, and treated. In addition, given the importance placed on the presence of injury throughout the criminal justice process, legal proceedings may be less likely initiated for women with dark skin.
The issue of skin color is a socially charged, relatively unexplored factor in injury science. Race/ethnicity have previously been used as a proxy for skin color, but the continuum of skin color clearly overlaps across races and ethnicities. For instance, in both our own sample and in previously reported research [45
], blacks had mean L* values lower than whites, but blacks had a broader range of L* values as compared to whites (eg, from the present study: SD for blacks, 12.09, and SD for whites, 6.42).
Little research before this report is available that explores differences in injury prevalence across the continuum of skin color. A careful reading of several reports of anogenital injury prevalence demonstrates that racial/ethnic differences may be present with regard to skin injury. Investigators have found differences in genital injury after vaginal births, with whites more likely than blacks to have third and fourth degree perineal lacerations and tears [46
]. Authors of published series of sexual assault cases also have found racial differences. In a retrospective review of medical records, Cartwright [48
] found that white women of all ages had almost twice as frequent anogenital injuries as black women. Coker et al [49
] found that among male sexual assault survivors, their race (being white) was significantly associated with traumatic physical injury when adjusting for other correlates (AOR, 1.6; 95% CI, 1.1–2.4), but among women, injury was not significantly associated with race/ethnicity (AOR, 1.1; 95% CI, 0.9–1.3). From a community sample of sexual assault survivors, Sommers et al [50
] found a significant association between race (black vs white) and genital injury (AOR, 4.30; 95% CI, 1.09–25.98; P
= .03), indicating that the odds for genital injury among whites was more than four times greater than blacks. Thus, differences in injury prevalence between races/ethnicities have been reported, but few investigators have discussed them, and only one mentioned skin color as a factor in injury assessment [50
We suspect that differences in injury prevalence occur because of difficulties with injury detection in dark skin. An alternative but less likely explanation is that differences in injury prevalence result from differences in the innate properties of the skin based on skin color. This alternative explanation would be based on a theory that dark skin is in some way more elastic, or less likely to be injured, than light skin. Curiously, in spite of well-developed science in the area of skin mechanics [51
], no investigators report differences in skin elasticity among racial/ethnic groups. Investigators have studied skin elasticity in fair/white subjects with regard to their healed wounds [54
] and erythema [55
] and have studied the mechanobiologic features of scars in individuals with dark skin [56
], but no comparisons of skin elasticity based on constitutive (untanned) skin color differences were found in the scientific literature. Because there is no reason to suspect innate differences in skin elasticity based on the science available to us at this time, we suggest that the differences we found in injury prevalence between races/ethnicities are due to problems with injury detection and not differences in skin elasticity related to skin color.
4.1. Criminal justice implications
Our reported injury prevalence (55% overall) falls within estimates of the reported injury prevalence after consensual sexual intercourse [8
]. Some investigators have previously found an injury prevalence as high as 61% to 73% after consensual intercourse [13
]. From a criminal justice perspective, the importance of the proof of injury prevalence is relevant for 2 primary reasons. First, during the last 10 years, the annual National Crime Victimization Survey repeatedly has reported that black women have higher rape/sexual assault rates compared to white women [57
]. Second, national victimization surveys, including the National Crime Victimization Survey, reported that a reason for a substantial proportion of women not reporting their sexual victimization to the police is the “lack of proof” that an incident happened [57
Forensic documentation of anogenital injuries influences decision making throughout the criminal justice process, especially at pivotal gate-keeping stages. For example, in 2 studies, McGregor et al [4
] reported that the presence of moderate or severe injury (AOR, 3.33; 95% CI, 1.06–10.42; P
< .0001) was significantly associated with the filing of charges after sexual assault and specifically, moderate injury (eg, genitalia lacerations, abrasions) was significantly related to the filling of charges (AOR, 4.00; 95% CI, 1.63–9.84). Rambow et al [5
] found evidence that the presence of trauma was significantly related to the successful prosecution of sexual assault cases (χ2
= 7.85, df
= 1, P
< .01), and Gray-Eurom et al [3
] found that the presence of trauma (OR 1.92; 95% CI, 1.08–3.43) was significantly associated with a guilty conviction in sexual assault cases. Penttilä and Karhumen [60
] provided data that demonstrated the association between presence of severe injuries and the defendant being sentenced to prison that approached significance.
Evidence of anogenital injury is a part of a constellation of evidentiary factors of alleged rape (eg, DNA results, presence of a weapon) used by the complainant, law enforcement, attorneys, jury, and judge to make decisions. Further research into the biometric quantification of skin color may improve the validly and reliability of the identification and documentation of anogenital injury, thus affecting the quality of forensic evidence proffered and decisions made throughout the criminal justice process. Forensic evidence based on such improved measurement techniques could be used to corroborate other physical evidence and the victim’s testimony, influence more objective decision making, and ultimately contribute to enhancing the quality of justice for sexual assault victims of all skin color, regardless of their race/ethnicity.
Several limitations exist. The sample for the study was composed of community volunteers who underwent a forensic examination after consensual sexual intercourse; thus, there may be biases associated with participant self-selection. Although these findings may not be generalizable to the nonconsensual sexual intercourse population, they did replicate findings of health disparities related to race/ethnicity from a retrospective study of sexual assault survivors [50
]. Several variables, such as length of the sexual encounter, degree of lubrication, and penile size, may suffer from measurement error as they are self-report. Two other limitations are important when considering the internal and external validity of the study findings. First, the TEARS classification, although in standard use in clinical practice, has not undergone extensive testing for interobserver reliability. Second, 2 individuals performed all the examinations, and their findings may not be generalizable to other examiners.
Injury prevalence was calculated based on injury identification by 3 methods: visual inspection, colposcopic magnification, and toluidine blue staining. Although these 3 methods are considered state-of-the-art, human error may have led to injury misidentification: injuries may be missed or areas that are identified as injury may be pigment differences or structural changes.
4.3. Clinical recommendations and summary
Skin color plays a significant role in the assessment of anogenital injury and may be a source of health disparity. The novel findings from this study have clinical ramifications for those performing the forensic sexual assault examination. Practitioners need to increase their vigilance when examining individuals with dark skin to ensure that all injuries are identified, treated, and documented. Protocols should include a contrast medium of some sort to increase injury detection, but a need exists for development of alternatives to toluidine blue, a dark blue dye that adheres to abraded skin but does not provide much contrast to dark skin, that will allow for injury identification across all skin colors.
Our results also suggest that quantified measures of skin color are better predictors of injury occurrence and frequency than racial/ethnic identification. Further work is needed with refined biometric procedures and DIA to replicate this work. Measurement techniques then need to be modified for real world use so that they can easily incorporated into the standard forensic sexual assault examination in the clinical setting. The technology and imaging procedures used during the forensic examination may need to vary depending on the sexual assault survivor’s skin color. We suggest that disparities in injury detection may be a major contributor to the differences in anogenital injury prevalence and frequency in females with light and dark skin after consensual and perhaps non-consensual sexual intercourse. We suggest further that only improved clinical forensic sexual assault examination techniques that are appropriate for survivors across the entire continuum of skin color have the potential to reduce health disparities.