Patterns of sexual assault evidence and forensic evaluation: a systematic review and meta-analysis

Abstract

Background: The assessment of anogenital injury is a key element in both the clinical and forensic evaluation of a sexual assault. Nevertheless, the presence of injuries is not uncommon after a consensual act of intercourse, which inevitably raises difficulties in interpretation and medico, legal decision, making. Different prevalence of injuries, methods to detect them and individual biological characteristics have contributed to make forensic assessment even more complex. The authors of this research have been trying to gather and integrate systematically evidence on the characteristics of anogenital injury after sexual assault and consensual intercourse. Besides, they have also attempted to identify and understand the role of factors that change the detection of injury and its interpretation.

Methods: A systematic review and meta, analysis were conducted based on eight primary comparative and methodological studies, which were complemented by additional literature. Eligible studies were those that examined adult female populations after forensic or medical examination following sexual assault, consensual intercourse, or both. Data extracted comprised study characteristics, injury prevalence, anatomical distribution, injury type, and forensic examination methods. Besides pooled prevalence estimation, qualitative synthesis was also done to compare the injury patterns across exposure groups and to assess the impact of examination techniques.

Results: Across the studies included, the overall percentage of any anogenital injury was pooled and the prevalence of that pooled anogenital injury was estimated at 66% after sexual assault and 48% following consensual intercourse, thus survivors of sexual assault had higher injury occurrence but still with a great overlap. Abrasions and erythema were typical of both groups, whereas lacerations and bruising were more commonly linked with sexual assault. In general, the injuries distribution was most commonly located at the posterior fourchette and labial areas. Detection rates of injuries were very different depending on the way the examination was conducted. That is, injury identification was increased by colposcopy and toluidine blue dye as adjunctive techniques compared with naked eye examination. Besides that, biological and situational factors, such as tissue characteristics, previous sexual experience, age, and the time of the examination, were shown to have a significant impact on the presence and visibility of injuries.

Conclusion: Anogenital injuries are a common complaint among sexual assault survivors, but there is significant overlap with injuries resulting from consensual intercourse, which means that the presence of an injury alone has limited diagnostic specificity. Therefore, forensic interpretation should weigh physical findings along with clinical history and contextual evidence. It is crucial to standardize examination protocols and carry out further research on the biological and methodological factors of injury to enhance forensic sexual assault assessment accuracy and fairness