The influence of testosterone administration on pelvic organ changes and sexual functioning in transmasculine and gender-diverse persons: a quantitative assessment using magnetic resonance imaging

Gender-affirming hormone therapy for transmasculine and gender-diverse (TMGD)
persons assigned female at birth typically involves testosterone administration
to align physical traits with gender identity. Testosterone induces notable
changes in the pelvic and genital area, causing alterations in genital
microvasculature and sexual response. Clitoral hypertrophy is a
frequently-mentioned effect, but while external growth of the clitoris is
reported, no studies have quantified internal clitoral growth or its
relationship with androgens and sexual function. In addition to changes in the
clitoris, recent literature indicates that over 60% of TMGD persons experience
pelvic pain during sexual activity, with another study exploring a possible
link with changes in the pelvic floor musculature, which is known to be
androgen-sensitive. Again, the relation with sexual functioning is unclear.

This study aims to be the first to visualise changes in both clitoris and
pelvic floor musculature following testosterone administration and to explore
how these changes relate to sexual function. The primary objective of this
observational study is to examine clitoral and pelvic floor musculature volume
and percentage changes in volume in transmasculine and gender-diverse persons
prior to start of testosterone administration and after nine months of
treatment. The secondary objectives are to examine pelvic floor musculature and
clitoral volume and percentage changes in clitoral volume during audiovisual
sexual stimulus and to explore the association between self-reported sexual
function and changes in clitoral and pelvic floor musculature volume.

This is an observational cohort pre-post study with non-invasive measurements.
Participants will complete questionnaires and undergo magnetic resonance
imaging (MRI) during two visits to Amsterdam UMC, location AMC. During these
visits, they will view a neutral and an erotic film segment while the MRI
measurements are taken.

As this study will provide important insights into the anatomical and
functional changes experienced by TMGD individuals initiating testosterone
therapy, successful completion will definitely have an impact within the fields
of sexual medicine and gender-diverse healthcare. Specifically, it will give
information on how testosterone affects both external and internal clitoral
structures, as well as the pelvic floor musculature. By using dynamic MRI to
visualize these changes (in response to sexual stimuli), we aim to fill gaps in
the knowledge on physiological changes associated with testosterone. The risks
associated with this study are small: they are related to possible intruding
questions and discomfort associated with genital MRI testing; through extensive
selection and preparation beforehand, chances of this research triggering
feelings of dysphoria will be kept at a minimal.
MRI itself is a non-invasive imaging modality. All participants will receive
extensive information about the MRI procedures and will be screened on
contra-indications beforehand. There will be minor discomfort caused by having
to lie still for several minutes and being fixed in a small space. Subjects
suffering from claustrophobia are therefore excluded from participation.
Considering the coaching and preparation beforehand, we consider the burden of
this procedure to be minimal. Since MR imaging is considered a safe standard
medical procedure, we evaluate the risks associated with MR scanning to be
negligible.
Altogether, this pilot study can offer data to healthcare providers that can
help them manage expectations and addressing sexual dysfunction in TMGD
individuals. As improved understanding of pelvic anatomical changes will lead
to more personalized care and more successful targeted interventions, it can
improve patient outcomes. Moreover, the study can serve as the foundation for
future research on sexual wellbeing in TMGD individuals. This is all the more
important within a minority community where existing data is sparse, while the
need for more knowledge is highly present in clinicians and patients alike.