General Considerations on Medical Aspects of Child sexual abuse
The majority of abused children show no physical evidence. The frequency of normal findings varies from 23 to 94%, based on differences in definition of abuse and findings [Adams et al., 1994; Bays and Chadwick, 1993; De Jong and Rose, 1989; Kellog et al., 1998; Bowen and Aldous, 1999]. A meta-analysis by Bays and Chadwick  reported normal findings in more than 50% of abuse victims. In a study by Adams et al.  with the subtitle ‘It’s normal to be normal’, the authors examined 236 children with perpetrator conviction for sexual abuse who had normal genital examination findings in 28%, nonspecific in 49%, suspicious in 9%, and abnormal findings in 14%.
In case of perpetrator confession of penile-vaginal penetration, still 39% of the victims presented with normal findings in another report [Muram, 1989a]. In a recent study by Berenson et al. , only 2% of 192 girls between 3 and 8 years who reported digital-vaginal or penile-vaginal penetration had hymenal transections, perforations or deep posterior notches. The majority of girls were not examined acutely however. Heger et al.  examined 2,384 children and found normal exams in 95% of children who had disclosed and in 92% in girls who reported penetration.
The most important reason for the paucity of abnormal findings is the nature of the abuse itself. Frequently it does not involve physical contact sufficient enough to produce physical sequelae (fondling, oral abuse, masturbation, pornographic photography and others). Therefore the ‘absence of evidence is no evidence of absence’ (of abuse). Furthermore, smaller children often do not have sufficient knowledge about their anatomy in order to appropriately describe what exactly has occurred. The may interpret any diffuse pain in the anogenital area as invasive or penetrative. There are no data at which age children are developmentally capable of differentiating ‘on’ from ‘in’. Medically, ‘penetration’ is defined as the introduction of an object beyond the hymenal membrane into the vagina. In a jurisdictional view however, even slight penetration between the labia majora constitutes the legal term ‘penetration’.
Finally, the outcome and traumatizing nature of CSA is not primarily affected by the fact if penetration has occurred or if medical signs of trauma are evident [Finkel and De Jong, 2001; Finkel and Giardino, 2002].
A significant difference exists between CSA and rape and contributes to the diagnostic difficulties. Children are seldom forcibly raped and in the majority of cases force and restraint are not used. Therefore only some children have obvious sequelae caused by more serious injuries. And those who do, seldom present acutely so that the retrospective interpretation of healed trauma constitutes the major difficulty in evaluating these findings. Those children and adolescents who are victims of stranger assaults or rape will rather present acutely with evident findings, due to familial support and immediate action taken. Acute findings are easier to document but children seldom disclose in this phase.
Besides the absence of findings due to a physically non-traumatizing abuse, the enormous potential of rapid and often complete healing of most anogenital injuries contributes to the paucity of specific findings. In selected cases, even transections of the prepubertal hymen have been demonstrated to heal to integrity. A single incomplete hymenal rupture may heal as early as 9 days after trauma. More typically though, complete transections to the base of the hymen lead to permanent disfigurations of the hymenal membrane in form of a cleft or concavity [Teixeira, 1981; Bays and Chadwick, 1993; McCann et al., 1992; McCann, 1998; Finkel and De Jong, 2001; Finkel and Giardino, 2002].
The frequency of findings related to abuse will also depend on variables inherent to the healthcare system: qualification and willingness of the examiner to acknowledge CSA as a possible differential diagnosis, the timing of the examination, qualified and empathetic preparation of the child (in order to obtain consent and cooperation), a good lighting source, good documentation for peer review or second opinion and to a smaller amount the availability of technical support (generally a colposcope for magnification, lighting and documentation).
Revision date: June 18, 2011
Last revised: by Janet A. Staessen, MD, PhD