Introduction: Interpretation of genital findings is a key component of the medical examination for suspected child sexual abuse. This study seeks to review the extent of evidence-based research on genital findings in prepubertal girls.
Methods: Literature review on normal genital anatomy in non-abused girls, case control studies comparing abused and non-abused girls, and observations of healing where the mechanism of injury is documented.
Results: A prolific literature exists on children examined for suspected abuse. By comparison there is a very little literature on children screened for non-abuse. Primary data on normal genital anatomy in girls after the neonatal period was found in 10 papers of non-abused girls and 6 case-control studies. The screening methods used to ensure that only non-abused children were assigned to non-abused groups were of variable standards. The evidence base on prepubertal girls selected for non-abuse using robust methodology is very small. The evidence base on healing of documented genital injury is contained in two case series, and a small number of case reports. Almost the entire evidence base on prepubertal genital anatomy in girls is derived from the USA.
Conclusions: Knowledge of the American studies and the limited extent of the total evidence base are essential to interpretation. A posterior rim of hymen measuring at least 1mm is always present unless there has been trauma. There is such a wide range of normal hymen orifice size, that measurements are generally unhelpful. Genital injuries generally heal rapidly and most heal without residua. Hymen healing does not leave scarring, but scarring or vascular changes may occur to surrounding tissues. Except for deep lacerations hymen injury leaves no evidence of trauma. A full thickness transection through the posterior hymen is reliable evidence of trauma and does not heal without surgical repair.