Objective: To determine the usefulness of measurements of the vaginal opening and amount of hymenal tissue present inferiorly and laterally in the diagnosis of vaginal penetration.
Methods: The transhymenal diameters and the amount of tissue present between the hymenal edge and vestibule inferiorly at 6 o'clock and laterally at 3 o'clock and 9 o'clock were measured from photographs of 189 prepubertal children with a validated history of digital or penile penetration and 197 children who denied previous sexual abuse. Statistical analyses were conducted to compare the mean values and hymenal symmetry between groups as well as to determine the sensitivity and specificity of various cutoff points.
Results: Comparison of the mean diameters demonstrated that children with a penetration history had a significantly larger transverse opening than nonabused children when examined in the knee-chest position (5.6 vs 4.6 mm). However, there was extensive overlap in measurements between the 2 groups. No significant differences were noted between groups in the size of the vertical diameter, the amount of tissue present inferiorly or laterally, or the symmetry of the hymen in either position. Children with previous penetration were more likely than nonabused children to have a horizontal opening measuring >6.5 mm in the knee-chest position, but the sensitivity and specificity of this test were low (29% and 86%, respectively). Higher values had better specificity but very low sensitivity. Less than 1.0 mm of hymenal tissue was detected at 6 o'clock only in those with a history of penetration (100% specificity), but the sensitivity was low (1%-2%).
Conclusion: Most hymenal measurements lack adequate sensitivity or specificity to be used to confirm previous penetration. Less than 1.0 mm of hymenal tissue at 6 o'clock was detected only in victims of abuse, but the usefulness of this test is limited by the rarity of this finding.