Validation set correlates of anogenital injury after sexual assault

Forensic investigators remain unsure exactly why some sexual assault victims display acute injury while others do not. This investigation explores potential reasons for these differential findings among female victims.

This cross-sectional analysis examined data from consecutive female sexual assault victims, at least 12 years old, who agreed to a forensic exam between November 1, 2002, and November 30, 2006. Exams utilized colposcopy, anoscopy, macrodigital imaging, and toluidine blue dye to delineate anogenital injury (AGI), which was defined as the presence of recorded anogenital abrasions, tears, or ecchymosis. Demographic variables of the victim, including sexual experience and reproductive parity, and assault characteristics were recorded in the database for bivariate and multivariate analysis with AGI.

Forty-nine percent of the initial 3,356 patients displayed AGI. Of this total, 2,879 cases included complete data for all variables and were included in the multivariate logistic regression model. A statistically significant increased risk for AGI was noted with: educational status (odds ratio [OR] 1.53, 95% CI = 1.25 to 1.87); vaginal or attempted penetration using penis (OR 2.29, 95% CI = 1.74 to 3.01), finger (OR 1.61, 95% CI = 1.88 to 1.94), or object (OR 3.19, 95% CI = 1.52 to 6.68); anal-penile penetration (OR 2.00, 95% CI = 1.57 to 2.54); alcohol involvement (OR 1.25, 95% CI = 1.04 to 1.50); and virgin status of victim (OR 1.38, 95% CI = 1.11 to 1.71). Victims were less likely to display AGI with a longer postcoital interval (OR 0.50, 95% CI = 0.39 to 0.65) and increased parity (OR 0.76, 95% CI = 0.57 to 0.99).

Approximately half the patients displayed AGI. This rate is higher than earlier studies, but consistent with current investigations utilizing similar injury detection methods. The correlates of injury found reinforce the findings of prior studies, while prompting questions for future study.