Vaginal self-lubrication following peritoneal, penile inversion, and colonic gender-affirming vaginoplasty: a physiologic, anatomic, and histologic review

INTRODUCTION: Vaginal self-lubrication is central to the sexual satisfaction and healthy genitourinary function of patients who have undergone gender-affirming vaginoplasty (GAV). Secretory capacities of different neovaginal lining tissues have been variably described in the literature, with little evidence-based consensus on their success in providing a functionally self-lubricating neovagina. We review the existing neovaginal lubrication data and the anatomy, histology, and physiology of penile and scrotal skin, colon, and peritoneum to better characterize their capacity to be functionally self-lubricating when used as neovaginal lining. OBJECTIVES: The study sought to review and compare the merits of penile and scrotal skin grafts, spatulated urethra, colon, and peritoneal flaps to produce functional lubrication analogous to that of the natal vagina in the setting of GAV. METHODS: We conducted a systematic review following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Medline, EMBASE, ClinicalTrials.gov, and the Cochrane Library databases were searched for peer-reviewed studies published prior to December 12, 2022, that (1) included data specific to transfeminine individuals; (2) were full-text randomized controlled studies, case reports, case series, retrospective cohort studies, prospective cohort studies, qualitative studies, and cross-sectional studies; and (3) included specific discussion of vaginal lubrication or fluid secretion following GAV utilizing penile skin, colonic tissue, or peritoneum. RESULTS: We identified 580 studies, of which 28 met our inclusion criteria. Data on neovaginal lubrication were limited to qualitative clinician observations, patient-reported outcomes, and satisfaction measures. No studies quantifying neovaginal secretions were identified for any GAV graft or flap technique. Anatomically, penile and scrotal skin have no self-lubricating potential, though penile inversion vaginoplasty may produce some sexually responsive secretory fluid when urethral tissue is incorporated and lubricating genitourinary accessory glands are retained. Colonic and peritoneal tissues both have secretory capacity, but fluid production by these tissues is continuous, nonresponsive to sexual arousal, and likely inappropriate in volume, and so may not meet the needs or expectations of some patients. The impact of surgical tissue translocation on their innate secretory function has not been documented. CONCLUSIONS: None of penile/scrotal skin, colon, or peritoneum provides functional neovaginal lubrication comparable to that of the adult natal vagina. Each tissue has limitations, particularly with respect to inappropriate volume and/or chronicity of secretions. The existing evidence does not support recommending one GAV technique over others based on lubrication outcomes. Finally, difficulty distinguishing between physiologic and pathologic neovaginal fluid secretion may confound the assessment of neovaginal self-lubrication, as many pathologies of the neovagina present with symptomatic discharge.