The Nugent score is an inappropriate diagnostic tool for neovaginal bacteria in transfeminine people

Abstract Background Many transfeminine people (assigned male at birth with feminine gender identities) undergo vaginoplasty, a surgical procedure constructing a neovagina, typically using penile and scrotal tissue. In cisgender females, gynecological symptoms (pain, discharge, malodor) are often attributed to bacterial vaginosis, which can be diagnosed using Nugent scoring of gram-stained vaginal smears. The Nugent score assesses the abundance of large gram-positive rods versus small or curved gram-variable rods, traditionally for the detection of Lactobacillus, Gardnerella vaginalis, and Mobiluncus, respectively. Although unvalidated, this method is frequently applied to neovaginal samples to diagnose gynecological symptoms and dysbiosis. This study assessed the Nugent score’s utility for diagnosing neovaginal dysbiosis in transfeminine people. Methods As a part of the TransBiota study, n = 39 transfeminine participants self-collected neovaginal smears. Smears were Gram stained and Nugent scored, and scores were correlated with data on neovaginal bacterial composition (16S rRNA gene sequencing), neovaginal cytokines (Luminex multiplex immunoassay), and self-reported symptoms. Results We show more than 70% of neovaginal smears fell in the 7-10 Nugent score range, indicative of Bacterial Vaginosis in cisgender women. However, scores fail to correlate with the abundance of Nugent-targeted bacteria. Bacteria with similar morphotypes, but not belonging to Lactobacillus, Gardnerella, or Mobiluncus, are highly abundant and prevalent in the neovagina. Nugent score also fails to predict local inflammation or clinical symptoms. Conclusions The Nugent score is not an effective tool to identify neovaginal dysbiosis or indicators of health in transfeminine individuals. Clinicians need the development of accurate, evidence-based diagnostic tools for the neovagina.