The Bilateral Pedicled Epilated Scrotal Flap: A Powerful Adjunctive for Creation of More Neovaginal Depth in Penile Inversion Vaginoplasty

Tim H.J. Nijhuis MD, PhD; Müjde Özer MD; Wouter B. van der Sluis MD, PhD; Muhammed Al-Tamini MD; Ali Salim MD; Philip Thomas MB, BS, FRCS (Urol); James Bellringer MB, FRCS (Urol), FECSM; Mark-Bram Bouman MD, PhD, FECSM

FIRST PUBLISHED: March 20, 2020 – The Journal of Sexual Medicine

DOI: https://doi.org/10.1016/j.jsxm.2020.02.024

Introduction

Penile inversion vaginoplasty is a common gender-affirmation procedure for transgender women. Penile skin can be used to create a neovagina, but some patients do not have enough skin available for adequate vaginal depth.

This study discusses the use of the bilateral epilated scrotal flap (BPES-flap) as an “adjunctive” technique for patients in this situation.

Indications for Procedure 

A neovaginal depth of 12 cm and an intravaginal diameter of 3.5 cm should allow adequate neovaginal intercourse. Accordingly, the planned inverted penile skin flap should be 12 cm long, plus the distance of the perineum, for penile inversion vaginoplasty. If there is not enough skin to line the neovaginal cavity, skin grafts or the purposed BPES-flap is a possible solution.

Preoperative Preparation

Before surgery, hair should be permanently removed from the scrotal skin by laser or electrolysis. Patients should also see a pelvic floor physical therapist to learn more about postoperative dilatation.

Intraoperative Considerations

Procedural information was described as follows: 

Anatomy

There are several key anatomical units that need to be identified while harvesting this flap. Transversely, several layers should be identified: skin, dartos fascia, cremaster muscle (including the external spermatic fascia), and bulbospongious muscle. Appreciating these individual layers is important for the dissection of the BPES-flap because the flap is raised in a subfascial plane including the dartos fascia.

The vascularization is supplied by the superficial perineal artery that arises from the internal pudendal artery. After crossing the superficial transverse perineal muscle, the perineal artery runs between the bulbosponiosus and ischiocavernous muscles. The most distal branches supply the skin and dartos tunica in a cross-over pattern supplied by the bilateral vascularization.

The dimensions of the BPES-flap are limited by the perineoscrotal fold caudally and distally and the proximal limitation is the base of the penis (where the scrotum ends). Maximal lateral extension of the flap is determined by the need for scrotal skin to create the labia majora.

Surgical Planning

The BPES-flap is versatile and can be designed and implemented in several ways:

• When the inverted penile skin flap is of sufficient width but insufficient length, a fasciocutaneous rectangular flap is designed for neovaginal depth creation. The vascular pedicle of the dorsally based flap is de-epithelialized.
• When the inverted penile skin flap is of sufficient length but is too narrow, an axial fasciocutaneous flap can be designed. The inverted penile skin flap is incised longitudinally, and the axial flap is interposed to create more neovaginal width. This approach was described earlier in various penoscrotal vaginoplasty techniques. The BPES-flap forms the posterior, and the incised inverted penile skin flap is used for the lateral and anterior vaginal wall.
• When the inverted penile skin flap is of both insufficient length and width, a combination of the aforementioned 2 techniques can be used. An axial T-shaped flap is designed. No de-epithelialization is performed. The base of the T is interposed in the longitudinally incised penile skin flap, and the rectangular top of the flap is used for neovaginal depth creation.

Prime Example

Scrotal flap length: In this example, the penile skin flap length is 8 cm (frenar band to the base when retracting the penis–measuring ventral stretched penile skin) and has a width of 3.5 cm. The perineal length is 2 cm. The available penile skin to line the neovaginal cavity is 8 cm minus the length of the perineal length of 2 cm. Hence, to achieve 12 cm of lined neovaginal depth, an additional 6 cm of neovaginal lining has to be acquired. A scrotal flap of 6 cm long needs to be harvested.

Scrotal flap width: Using the mathematical formula for calculating circumference (2 π r), the width of the scrotal flap needs to be approximately 11 cm to achieve a diameter of approximately 3.5 cm.

Determining the Flap Pedicle Length

In summary, the following algorithm could help in calculating the required extra length:

• Define the desired neovaginal depth and diameter.
• Measure the penile length and perineal length.
• Calculate the width of the BPES-flap: 2 π r (r is the radius; in this case, half of the desired vaginal diameter).
• Define the pedicle length: penile length subtracted by the perineal length.
• Define the caudal starting point of the BPES-flap: pedicle length measured from the introitus.
• Draw the BPES-flap dimensions with the scrotal skin stretched.

Scrotal Flap Dissection 

The scrotal flap is harvested in a subfascial plane (subdartos fascia), leaving the cremaster muscle and external spermatic fascia intact. The raised flap now includes only the skin and the dartos fascia. The scrotal flap can be transposed through the penile skin and sutured to it in an interdigitating fashion to form the eventual top of the neovagina. This is best performed before inverting the penile skin into the cavity, to facilitate easy suturing. The scrotal flap will form the most distal part of the neovaginal canal, and the de-epithelialized base of the scrotal flap will be placed posterior to the penile inverted skin. A modification of this scrotal flap is the T-flap. This modification uses in fact a rectangular perineal flap in conjunction with the scrotal flap on the same pedicle to create more width of the neovaginal canal. The penile skin is incised, and the scrotal skin is maintained in the midline (1–2 cm in width) and sutured to the penile skin to enlarge the diameter.

Postoperative Management and Follow-Up

After surgery, a neovaginal tampon is placed in the neovaginal canal for 5 days. When there are no postoperative problems, patients begin dilating twice a day and rinsing the neovagina. Follow-up appointments are scheduled over the next two years.

Outcomes

Forty-two patients with a median age of 28 years participated in this study. There were treated in 3 gender affirmation centers.

Mean penile length and width before surgery was 9 ± 3.1 and 2.9 ± 0.2 cm respectively.

After a mean follow up 13 ± 10 months, one patient had total flap necrosis, and another had partial flap necrosis. Three patients experienced partial prolapse of the top.

Mean vaginal depth for all patents was 13.5 ±1.3 cm, and mean width was 3.3 ± 1.3 cm.

Discussion 

The BPES-flap procedure may have advantages for patients who have a shortage of penile skin, but sufficient scrotal skin. For example, a “quick harvest” may mean less operative time compared to procedures using skin grafts. However, this study did not measure intraoperative time; the topic will be further researched.

Patients undergoing the BPES-flap procedure are at risk for partial prolapse. In this study, three patients experienced some degree of prolapse. However, one did not follow postoperative instructions due to a language barrier, and another did not use the standard prescribed laxative for constipation. A longer packing period, or re-packing after 5 days, might reduce this risk.

In some instances using the BPES-flap procedure, there might not be enough scrotal skin to created labia majora. Patients may need to decide whether they would prefer well-vascularized neovaginal depth or more prominent labia majora.

Different BPES flap designs are possible to accommodate different scenarios. For example, a T-flap design might be appropriate for patients with insufficient penile skin length and width.

Use of the flap (as opposed to full-thickness skin grafts) might also prevent circular scar contraction, “which could result in loss of depth.” However, dilation is essential for maintaining depth and patients should be followed for the long term for further evaluation.

“We recommend gender surgeons to incorporate this scrotal flap in their surgical armamentarium, for the BPES-flap is a powerful adjunctive for creation of more neovaginal depth in a subset of transgender women with relatively insufficient amount of penile skin and a normal to large scrotum.”