Do we miss half of the injuries sustained during rape because we cannot see them? An overview of the use of toluidine blue tissue stain in the medical assessment of rape cases

J M Kotzé,H Brits

doi:10.4102/safp.v60i2.4868

Abstract

The prosecution of rape cases is difficult due to the absence of eyewitnesses. McCauley found that the detection of vaginal lacerations increased from one in 24 to 14 in 24 in reported adult rape cases when toluidine blue was used. Proof of injuries consistent with sexual penetration adds significantly to the evidentiary value of the medico-legal testimony. Although rape is not a clinical diagnosis and there are no diagnostic criteria to confirm rape, the possibility of genital injury during rape far exceeds the possibility of injury with consensual intercourse. If a complete examination, including the use of toluidine blue, is not used a rapist may walk away to rape again, while the victims remain with the stigma that they may have made a false allegation. Toluidine blue is a basic thiazine metachromatic dye. It has a high affinity for acidic tissue components, thereby staining tissues rich in DNA and RNA. The epithelium of the external genitalia does not have nucleated cells and prevents contact of stain with nuclei. Where the epithelium is damaged and the underlying nucleated cells are exposed, the nuclei stain blue. Injuries sustained during genital penetration show a distinctive distribution.Toluidine blue stain is easy and safe to use, available, inexpensive and does not interfere with other medico-legal evidence, therefore it is recommended to be used in the examination of all cases of alleged rape.

Highlights

It may be that medical examinations are routinely done in a way that prevents the detection of a large percentage of anogenital injuries
The presence of anogenital injuries in rape cases is of major importance in court hearings
With the use of toluidine blue, injuries are demonstrated in more rape victims

Summary

Introduction

In adult and adolescent rape cases, conviction is more likely if there are visible injuries.[1,2,3] It may be that medical examinations are routinely done in a way that prevents the detection of a large percentage of anogenital injuries. Visibility of the nature of injuries, number of injuries and number of anatomical sites injured can be vastly improved utilising a nuclear tissue stain such as toluidine blue, to highlight epithelial damage.[9] Injuries can either be confirmed after visual examination with the naked eye, or detected when not visible without the staining technique by the use of a scientific process to increase visibility. A 1% aqueous solution of toluidine blue is applied with an earbud to the area behind the 3–9 o’clock line of the posterior fourchette or the peri-anal area.

Results

Conclusion