The Use of Autologous Flaps in Pelvic Reconstructive Surgery
In female pelvic and reconstructive surgery, pedicled autologous tissue flaps provide the benefits of tissue volume and structural reconstruction. Autologous tissue flaps have been used in complex reconstruction as interposition flaps which increase bulk and augment vascular supply to a needed area. Interposition flaps have typically been reserved for multifaceted or recurrent conditions such as complex or radiation-induced fistulas. Flaps can also be used as tissue replacement where surgical extirpation or congenital absence creates a structural need. Autologous tissue flaps can also be used to provide volume and fill space after an exenterative procedure, such as a pelvic exenteration for malignancy. Alternatively, they can also be used to create a neovagina due to congenital absence, atresia due to radiation damage, or iatrogenic extirpation due to malignancy.
Prior to the advent of synthetic materials, the need for tissue augmentation in pelvic reconstructive surgery was recognized. As far back as 1928, Heinrich Martius,1 described the bulbocavernosus flap as an interposition pedicled, vascularized flap for repair of vesicovaginal fistula. Alternatively, interposition flaps for abdominal surgery have commonly used pedicled omentum or rectus abdominis flaps. Both have the robust vascular supply and bulk needed to apply as an interposition when an abdominal approach is preferred or required. A flap is tissue which maintains its blood supply but is mobilized to a different location. For pelvic reconstructive surgery, the majority of flaps described are pedicled flaps which maintain an identified vascular pedicle while the tissue supplied by that blood flow is mobilized to a different location around a fulcrum. Alternatively, free flaps can also be used. This involves transecting the artery and vein supplying the tissue and performing a microvascular anastomosis at a distant location to reestablish blood flow. Free flap reconstruction is not typically used in urogynecologic surgery. This chapter focuses on pelvic floor conditions which benefit from the utilization of pedicled autologous tissue flaps.
The most common surgical scenarios for interposition flaps in urogynecology are fistulas. Fistulas are described as an aberrant connection between two viscera. The most common fistulas of the reproductive tract include vesicovaginal and rectovaginal fistula (Fig. 52.1). Fistulas, although rare in the United States, are debilitating and significantly diminish the quality of life of women. They are most commonly found as a result of gynecologic surgery, although in the developing world are primarily associated with obstetric injury. Success rates with surgical correction for vesicovaginal fistula are high, 70% to 100%.2,3 Although two approaches are described, vaginal and abdominal, there is a lack of comparative studies to show superiority of one modality, although the vaginal approach, by definition, has less morbidity due to the lack of abdominal incisions. The open abdominal approach has been shown to have increased hospitalization time and cost as compared to vaginal approach in one cost-effectiveness study.4 However, with complex or recurrent vesicovaginal fistula, interposition flaps can be considered to improve vascular supply and healing. There is a lack of comparative data guiding when to use interposition flaps for fistula. Singh et al.5 performed a randomized controlled trial of obstetric and gynecologic fistulas with randomization with or without interposition flaps. Overall success was 97% with or without interposition whether vaginal or abdominal approach. Given the high success, standard utilization of interposition flap is not recommended, although larger studies would likely be necessary to show a statistical difference. Therefore, surgeons should consider interposition flaps for fistula in cases of recurrent fistula, prior surgery with failure, and complex fistulas, such as radiation fistulas or large fistulas, which may lack adequate vascular supply for proper healing. Placing an interposition flap would provide increased vascular supply and avoiding apposing suture lines, which may benefit surgical outcome.
Pelvic exenterative procedures are typically performed in cases of gynecologic, urologic, or colorectal malignancy. Following extirpation of pelvic organs, bulky interposition can be used to decrease the risk of seroma and abscess formation. Omental interposition may be adequate, but a larger flap may be necessary depending on the patient’s body habitus, and if the omentum is not available or robust. Alternatively, a myocutaneous flap may assist in closing a perineal skin defect and in addition can be used to create a neovagina following pelvic exenteration procedures, if a patient desires preservation of sexual function. A recent systematic review comparing primary closure and myocutaneous flap evaluated outcomes in 566 patients.6 Devulapalli et al.6 described significantly increased risk of a perineal wound complication when a myocutaneous flap was not used. When the patient has desire for sexual function following exenteration, the myocutaneous flap can be mobilized to create a vaginal canal and provide a patent vagina for intercourse. Dilation and/or vaginal intercourse is likely necessary to maintain vaginal caliber. Casey et al.7 and Scott et al.8 described postoperative sexual function after neovagina use. Evaluating multiple different routes of neovagina creation, overall sexual function with vaginal intercourse was approximately 47%. When the cutaneous portion is not required, a less complicated rectus abdominis interposition flap can be performed to fill dead space following exenterative procedures.
Knowledge of the perineal anatomy and vascular supply is critical when considering the use of a perineal approach to a flap. The vascular supply to the perineum originates from branches of the internal iliac artery and the femoral artery. The anterior perineum is supplied by the external pudendal artery, superficial, and deep, originating from the femoral artery. The more robust internal pudendal artery supplies the blood supply mainly to the posterior perineum, although distal branches including the dorsal clitoral artery supply portions of the anterior perineum.9 Interposition pedicled flaps require an intact blood supply to survive, and therefore, a thorough understanding of this anatomy is important.
Martius labial fat pad flap
Vesicovaginal fistula repair can be approached either vaginally or abdominally. Vaginal approach is less invasive and amenable when there is adequate vaginal caliber and distal location of the fistula. With this approach, the most amenable interposition flap is the Martius flap, or bulbocavernosus flap. The original description of the Martius flap included the bulbocavernosus muscle, and the dissection was performed more medially.1 However, modification of this flap moved to exclusion of the muscle and utilization of the labial fat pad lateral to the muscle. This may decrease the risk of hemorrhage and damage to surrounding structures, such as the erectile function of the vestibular bulb.10 Despite the lack of muscular tissue, the fat pad carries adequate vascular supply for an interposition flap as demonstrated by multiple clinical studies.