Bulbocavernosus Muscle and Fat Pad Supplement

The Martius fibrofatty flap serves as a source of a substantial, well-vascularized tissue to provide coverage in distal vaginal repairs. The Martius flap has a greater tensile strength than typical fatty tissue because of a superficial fibrous layer (similar to the tunica dartos in the male) and fibrous septae throughout the adipose tissue. The superior vascular pedicle derives from the external pudendal artery (femoral), whereas the inferior blood supply derives from the posterior labial vessels, branches of the internal pudendal artery (internal iliac). These vessels form a vascular plexus within the tissue, which allows this flap to be divided either superiorly or inferiorly while maintaining good vascularity, providing a rare versatility of mobilization ( Fig. 85.1 ).


Options for mobilization.

Harvest of this flap will leave a cosmetic defect in the affected labia immediately after surgery, but patients can be counseled that, over time, this defect will fill with new fatty tissue. The long-term cosmetic outcome is typically excellent.

The Martius flap is the preferred flap for fistula repairs involving the trigone, bladder neck, and urethra and can also be used for coverage of distal rectovaginal fistulas. This flap is commonly harvested after fistula repair, before closure of the vaginal wall as an interposition layer to prevent recurrence. For proximal fistulas, however, the traction on the flap required to cover the defect may compromise the blood supply; therefore, in proximal locations, interposition of peritoneum is preferred.

The Martius flap is also useful in the repair of iatrogenic injuries to the vagina. With the widespread use of augmented polypropylene meshes for prolapse repairs and midurethral slings, cases of extrusions of these materials through the vaginal wall or erosions into the urethra, bladder, or rectum are accumulating. When such complications occur, removal of the mesh is necessary, but may damage these organs and destroy the overlying fibromuscular tissue and vaginal wall. The flaps described here can be used in distal locations should there be insufficient tissue for coverage of the defect created by mesh removal.

In patients with urinary retention resulting from fixation of the urethra to the pubic bone after prior pelvic surgery, radiation, or trauma, a Martius flap can also be placed between the urethra and the pubic bone after suprameatal urethrolysis to prevent recurrent urethral fixation.

When closure of the bladder neck or urethrectomy is required, a Martius flap can also be placed over the closure site to protect the repair.

Labial Fibrofatty Tissue Flap/Modified Martius Flap

The classic Martius flap, originally described in 1928, utilized a combined bulbocavernosus muscle and labial fibrofatty tissue flap. As the width of the bulbocavernosus is limited, use of a unilateral flap may be insufficient for coverage of a larger area. Harvest of this flap also creates a large defect with poor cosmetic outcomes. In addition, the bulbocavernosus muscle functions as a constrictor muscle of the erectile tissue of the clitoris; harvest of the muscle can negatively impact sexual function and satisfaction. For these reasons, use of the classic Martius flap has been abandoned in favor of harvest of the fibrofatty tissue of the labia alone in a modified Martius procedure. Harvest of the labial fat pad alone is less morbid and provides a similarly well-vascularized, bulky flap for interposition as the classic procedure.

Palpate the bulbocavernosus muscle and the associated labial fat pad between an index finger placed just inside the hymenal ring and a thumb on the labia majora.

Make a vertical incision in the mid-labia majora, lateral to the border of the bulbocavernosus muscle ( Fig. 85.2 ).


Vertical incision in the mid–labia majora, lateral to the border of the bulbocavernosus muscle.

Separate the skin from the flap using a Metzenbaum scissor. The flap extends from the medial border of the bulbocavernosus muscle to the crural fold laterally. Continue this dissection down along the medial and lateral margins of the fat pad to the underlying Colles fascia overlying the adductor muscles posteriorly. After visualizing the glistening, white surface of the fascia, use of the Army-Navy retractors can assist with blunt dissection to attain complete exposure of the flap ( Fig. 85.3 ).


Blunt dissection to attain complete exposure of the flap.

Near its insertion to the pubis, create a tunnel along the adductor fascia underneath the fat pad with a right angle clamp. A Penrose drain can be passed through the tunnel to facilitate further dissection ( Fig. 85.4 ).


Creation of a tunnel along the adductor fascia underneath the fat pad.

Typically for repairs of the distal vagina, a posterior-based flap is used. Continue to separate the flap from the adductor fascia traveling superiorly, then clamp and transect the anterior segment as close as possible to the pubic symphysis. Ligate the superior vascular pedicle with a suture ligature. To facilitate easier passage of the flap to the appropriate position over the vaginal repair, a figure-of-eight marking suture can be placed in the transected margin of the flap if desired. Gently mobilize the flap for 6–8 cm inferiorly, taking care to avoid injuring the inferior vascular pedicle ( Fig. 85.5 ).


Mobilization of the flap.

While not commonly used, differences in patient anatomy may make it more advantageous to divide the inferior pedicle to facilitate more facile coverage of distal injuries. In these circumstances, instead of dividing the flap superiorly, place a large clamp across the inferior pedicle. As this portion of the flap tends to be broader than the superior segment, you may require a flatter clamp, such as a Pean clamp.

Under finger guidance, use a Mayo clamp to develop a tunnel starting at the medial margin of the labial incision close to the base of the dissected flap extending to the site of the repair. Be sure that the tunnel is of sufficient width to accommodate the entire flap without restricting the blood supply. The tunnel can be enlarged with an index finger positioned against the tip of the clamp as it is withdrawn. It is important to ensure the tunnel is at an appropriate level, closer to the base of the flap, to allow the flap to rotate gently without kinking the vascular supply ( Fig. 85.6 ).


Development of a tunnel starting at the medial margin of the labial incision close to the base of the dissected flap extending to the site of the repair.

Pass the Mayo clamp from the vaginal repair site to the medial margin of the labial incision through this tunnel and grasp the free edge of the Martius flap (or marking suture). Transfer the fibrofatty flap through the tunnel to the repair site ( Fig. 85.7 ). Use an index finger in the lateral incision to guide the flap and prevent excessive tractioning that may damage the blood supply.


Transfer the fibrofatty flap through the tunnel to the repair site.

Suture the flap in place circumferentially over (around) the defect with a 2-0 or 3-0 dissolvable suture, such as polyglactin 910 (Vicryl; Ethicon) ( Fig. 85.8 ).


Suture the flap in place circumferentially over (around) the defect.

In the repair of posterior vaginal wall defects, as those seen after repair of a rectovaginal fistula or the removal of a posterior vaginal wall prolapse mesh, the Martius flap can be interposed between the repair and prerectal fascia to provide bulk to the rectovaginal septum and prevent fistula recurrence.

Advance a vaginal wall flap to cover the repair and reapproximate the tissue with interrupted 2-0 dissolvable sutures in figure-of-eight fashion ( Fig. 85.9 ).

Jan 2, 2020 | Posted by in UROLOGY | Comments Off on Bulbocavernosus Muscle and Fat Pad Supplement

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