An evaluation of the clinical impact of serological testing for herpes simplex virus in a regional UK sexual health service.

UK guidelines recommend herpes simplex virus (HSV) serology in limited situations, including distinguishing recent from established infections, excluding HSV in recurrent PCR negative lesions, identifying serodiscordant partners, or determining if a pregnant person with known HSV has both types. Challenges with testing include cost, delayed results, and interpretation. We aimed to determine whether HSV serology impacted on patient management. All HSV serology results between 04/10/2021 and 12/12/2025 at our large sexual health service in northwest England were reviewed and matched with HSV PCR results, and demographic and clinical data from patient records. 77 patients had HSV serology of whom 74 (96%) were female and 70 (91%) pregnant. Three (4%) tests were performed to exclude HSV as a cause of recurrent PCR negative ulceration, of which 2 were negative and 1 positive for HSV-1. Twelve (16%) tests were undertaken to identify serodiscordance with partners in pregnancy, with 1 demonstrating serodiscordance. Among pregnant patients, 34 (44%) had testing to identify new infection at first presentation with genital lesions, and 24 (31%) to identify whether both HSV types were present in a patient with known previous infection. Three (4%) patients had serological testing outside of guidelines. Serological testing influenced clinical management for 63 (82%) patients including 1/3 (33%) with recurrent PCR negative lesions, 12/12 (100%) of clinically discordant couples, 27/34 (79%) pregnant patients having serology to differentiate new from established infection on first presentation with lesions, 23/24 (96%) pregnant patients with known genital HSV having serology to determine whether they had antibodies to both HSV types, and 0/3 (0%) patients tested outside of UK guidelines. Despite challenges associated with performing and interpreting HSV serology, clinical management, especially pregnancy decisions, was impacted in the majority of cases. This underscores the necessity for streamlined protocols that facilitate testing as recommended in guidelines.