MP20-11: A Nomogram to Predict Vaginal Depth, Based on Available Penile and Scrotal Skin, for Penile Inversion Vaginoplasty: A Useful Tool for Decision Making and Surgical Planning

Shannon Smith*, Los Angeles, CA, Nance Yuan, Pasadena, CA, Michael Zaliznyak, Jenna Stelmar, Maurice Garcia, Los Angeles, CA

Introduction: To date, no nomogram exists to pre-operatively predict maximum achievable neovaginal depth before penile-inversion vaginoplasty (PIV) based on available penile & scrotal skin (SS). Maximal depth is determined by available skin and available anatomic space within the pelvis, and varies with surgical technique. Final achievable depth has been shown to be significantly important to patients. We created a nomogram to predict expected post-operative vaginal depth.

Methods: Retrospective review of all patients undergoing primary PIV at a single institution from June 2017 to February 2020 (n=46).  Pre-op: Dorsal penile skin length was measured on stretch from the base to 1-cm proximal to coronal ridge.  Midline scrotal skin length was measured on stretch from the penoscrotal junction to mid-scrotum, and mid-scrotum to mid-perineum.  Intra-op: Length of the tubularized scrotal skin segment measured on a dilator.  Immediate post-op: Final achievable vaginal depth measured with a dilator.  Fourteen patients underwent PIV without the use of scrotal skin (PIV-SS) and 32 patients had PIV+SS.

Results: In patients who underwent PIV-SS, the final vaginal depth (13.3 cm + 1.9) was 87% of pre-op measured penile skin length (15.3cm + 3.0; 0.87 +/- 0.17).  In patients who underwent PIV+SS, mean pre-op penile skin length was 11.1cm and pre-op midline scrotal length was 22.8 cm (+/-2.6 cm). This resulted in SS tube length of 12.3 cm (+/-3.2 cm). Mean final post-op vaginal canal depth was 15.6cm.  Using the previous metric, where final vaginal depth was 87% of dorsal penile skin length, we calculated the SS contributed on average 5.9 cm to the final depth of 15.6 cm (15.6 – [0.87 * 11.1 cm] = 5.9).  The mean intra-op SS tube length was 0.62 (+0.13) of pre-op scrotal skin length.  In 31 of 32 surgeries utilizing SS grafts, SS tube length was in excess of length necessary to achieve maximal vaginal depth, requiring trimming and discard.  Given that in most cases there was an excess of SS, final post-op depth equaled the maximal vaginal depth that could be achieved.

Conclusions: Our work suggests that preoperative penile shaft and SS length measurements can be used to predict final vaginal depth. SS grafts, when harvested and tubularized using optimal technique, appear to supply more skin than necessary to achieve maximal vaginal depth for the majority of patients.  Our findings suggest that for most patients it should not be necessary to include additional tissue sources, such as peritoneum, to create a vaginal canal during primary vaginoplasty.

Source of Funding: None