Exploring subjective and genital sexual response in transgender women upon addition of low-dose testosterone to feminizing gender-affirming hormone therapy: a feasibility study.

BACKGROUND: Transgender women using feminizing gender-affirming hormone therapy who underwent a gonadectomy generally have lower testosterone levels than cisgender women. It is unknown if testosterone supplementation can influence subjective and genital sexual response in transgender women and whether this can be measured using vaginal photoplethysmography.

AIM: This study aimed to assess the feasibility of measuring changes in subjective and genital sexual response in transgender women who underwent a penile inversion vaginoplasty after testosterone supplementation to physiological female concentrations.

METHODS: Transgender women received daily testosterone 2% transdermal gel, aiming for serum concentrations between 1.5 and 2.5 nmol/L for 12-20 weeks. Vaginal pulse amplitude (VPA) was measured during neutral, erotic fantasy, erotic film, and genital vibration stimulus blocks before and after testosterone supplementation. After each stimulus block, subjective sexual response was assessed. Sexual function, sexual excitability, and VPA measurement experience were assessed using questionnaires.

OUTCOMES: Change in mean VPA score and subjective sexual response after testosterone supplementation during neutral film, erotic fantasy, erotic film, and genital vibration.

RESULTS: Eight participants were included of whom seven completed the study. VPA during neutral film was significantly higher after testosterone supplementation [estimated ratio 2.7 (95% confidence interval {CI} 1.7-4.3), P < 0.001]. After testosterone supplementation, we observed no change in the degree of VPA response upon exposure to erotic fantasy [estimated ratio 1.4 (95% CI 0.68-2.8), P = 0.372], erotic film [estimated ratio 1.2 (95% CI 0.54-2.8), P = 0.629] and genital vibration [estimated ratio 1.2 (95% CI 0.46-2.9), P = 0.742] compared to before testosterone supplementation. After testosterone supplementation, participants reported significantly stronger feelings of sexual arousal, genital sensations, and positive affect in response to erotic fantasy and erotic film. Finally, there was a significant improvement in sexual function and sexual excitability assessed by questionnaires. VPA measurement was generally well-accepted.

CLINICAL IMPLICATIONS: Vaginal photoplethysmography can be used to assess changes in neovaginal perfusion in transgender women.

STRENGTHS & LIMITATIONS: This is the first study assessing genital and subjective sexual response to testosterone supplementation in transgender women. The lack of a placebo condition precludes any clinical conclusions.

CONCLUSION: Vaginal photoplethysmography can be used to assess changes in neovaginal vasocongestion after testosterone supplementation in transgender women. Explorative analyses suggest promising effects on subjective sexual response and an increase in general neovaginal perfusion. We found no difference in neovaginal vasocongestion after exposure to erotic stimuli before and after testosterone supplementation. Clinical benefit needs to be assessed in a blinded and placebo-controlled trial.