Discriminating between consensual intercourse and sexual assault: Genital-anal injury pattern in females

Assessment of genital-anal (GA) injuries following sexual assault promotes health and assists prosecutors to build a case. The pattern of injuries may help differentiate between consensual and non-consensual intercourse, bolster the survivors' credibility, and increase prosecutions in sexual assault cases.

To identify the constellation of G-A injury-related characteristics that most effectively discriminated between consensual sexual intercourse and sexual assault in females when controlling for intercourse-related variables.

We employed a comparative study with two groups: a prospective cohort group with consensual participants and a group derived from an existing sexual assault registry. In the prospective cohort, we performed a sexual assault forensic examination at baseline and following consensual sexual intercourse with females ≥21 years. We compared their injury patterns to the injury records of females ≥21 years who were sexual assaulted.

We enrolled a sample of 834 females: 528 consensual (63.3%) participants and 306 non-consensual (36.7%) registry cases. After controlling for race/ethnicity, age, and time between intercourse and examination, logistic regression analyses showed that the presence of an external genital tear increased the odds of non-consensual intercourse more than two times (adjusted odds ratio [AOR] = 2.70, 95% CI = 1.28-5.56). Logistic regression analyses also showed that the odds of non-consensual sexual intercourse were significantly greater with a lower prevalence and frequency of external and internal genital redness, lack of condom use and lubrication, and presence of anal penetration. Latent class analysis identified high and low G-A injury prevalence subgroups among both consensual and non-consensual samples. One subset of results emerged that may be indicative of non-consensual as compared to consensual intercourse: a higher prevalence of external genital and anal tears.

External genital tears occurred more frequently in the non-consensual sample and increased the odds of non-consensual intercourse more than two times. Anal tears, swelling, and ecchymosis and anal penetration were markers for non-consensual intercourse and should increase suspicion for lack of consent.