Background/introduction Testing for STI’s following sexual assault is routine. In cases were there is no other sexual activity other than the sexual assault, the assailant may be the source, and a positive result of significance in criminal investigation.

Aim(s)/objectives The potential forensic significance of STI results should be considered in each case.

Methods Discussion on information sharing of STI results is undertaken in cases referred to a sexual assault referral centre (SARC) with an absence of other sexual activity. This is documented and includes interpretation of results.

Case 1: An adolescent female, not previous sexually activity, vaginally raped, had a bacterial STI screen and serum save taken hours after the assault. Genital discomfort subsequently developed. A presumptive diagnosis of genital herpes made and tested. Herpes antibody testing was requested on samples taken; initially, when symptomatic and post symptoms.

Case 2: An elderly female, widowed several years earlier and sexually inactive since was vaginally raped. A bacterial STI screen was taken at the time initially and 14 days later.

Results Case 1 – HSV Type 2 confirmed. HSV antibodies initially absent were demonstrated in the post symptomatic sample. Case 2 – Initial Chlamydia trachomatis NAAT tested negative with a positive result at 2 weeks.

Discussion/conclusion The results are supportive of the assailants as the source. The positive Chlamydia result supported the penile vaginal penetration described, allowing consideration of a rape charge rather than a lesser offence. In both cases admissions were made pre-trial avoiding victims being called to court.