Forensic characteristics of hymenal injuries in child sexual abuse: evidence from a large case series in Vietnam.

Hymenal examination plays an important role in the forensic examination of suspected child sexual abuse. However, interpretation of hymenal findings remains challenging because of anatomical variation and subtle genital injuries, creating the potential for misinterpretation in medico-legal assessments. This study aimed to characterize hymenal morphology, hymenal injuries, and related forensic findings among female child sexual abuse victims in Vietnam and to examine patterns associated with repeated abuse. A retrospective analysis was conducted using forensic examination records of female children under 16 years of age referred for suspected sexual abuse at a specialized medico-legal center. Sociodemographic characteristics, assault-related information, hymenal morphology, and genital and extra-genital injuries were extracted from standardized forensic reports. Cases with diagnostic uncertainty or complex forensic findings were reviewed through expert consultation, and final conclusions were established by consensus within the forensic assessment team. A total of 443 children were included, with a mean age of 13.3 ± 2.6 years. The median interval between the alleged assault and forensic examination was 19 days (IQR: 4-89 days). Repeated sexual abuse accounted for 68.4% of cases. In multivariable analysis, older age (aOR = 1.25, 95% CI: 1.14-1.37), parental divorce (aOR = 1.95, 95% CI: 1.15-3.30), and abuse occurring in private or semi-private settings were independently associated with repeated sexual abuse. The annular hymen was the most frequently observed morphology (60.3%). Overall, 69.3% of cases showed combined hymenal dilatation and tear, followed by tear only (19.6%) and dilatation only (6.3%), while 4.7% had no hymenal injury. Most tears were old (81.7%) and located in the anterior region (65.2%). Additional genital and extra-genital injuries were uncommon. Repeated sexual abuse was common among examined victims. The annular hymen was the most frequently observed morphology, and combined hymenal dilatation and tear was the predominant injury pattern, while other genital and extra-genital injuries were uncommon. While these findings provide additional forensic reference data, no single hymenal morphology or injury pattern should be interpreted as diagnostic of sexual abuse in isolation and findings should be considered within the broader clinical and investigative context.