Assessment of neophallus length following metoidioplasty.

Background: An increasing number of gender diverse individuals are presenting for gender affirming care. An option for genital gender affirming surgery (gGAS) in transmasculine individuals is metoidioplasty, creating a small neophallus from enlarged clitoral tissue following prolonged testosterone exposure. The goal of this study is to understand factors which contribute to greater exposed neophallus length following metoidioplasty. Methods: We performed a retrospective chart review on patients presenting to a single academic institution who underwent a metoidioplasty. All operations were performed using the Belgrade technique with or without urethral lengthening depending on patient preference. Results: Twenty-seven patients underwent metoidioplasty from 2017-2022. Sixteen had recorded stretched clitoral length (pre-operatively) and exposed neophallus length (post-operatively). The median length of time on testosterone therapy was 4.6 years. The median stretched clitoral length was 5.8 cm, and exposed neophallus length was 6 cm. There was a strong correlation between pre-operative length and post-operative length (ρ=0.9; P<0.0001). There were no correlations between pre-operative length or exposed neophallus length and BMI (ρ=-0.02, P=0.93; ρ=0.05, P=0.83, respectively). Time on testosterone does not correlate with stretched clitoral length nor exposed neophallus length (ρ=-0.28, P=0.15; ρ=-0.35, P=0.18, respectively). Conclusions: Patients considering metoidioplasty often wonder how large their neophallus will be. We found that patients can expect exposed neophallus length to be about 0.6 cm longer than their pre-operative stretched clitoral length. No evidence of association of time on testosterone nor BMI with exposed neophallus length was found. This information is crucial for gender diverse patients to make informed decisions about gGAS.