The concept of using a patient’s own tissue as a “sling” to provide support under the urethra to treat urinary incontinence dates to the beginning of the twentieth century; however, it was not until the last quarter of the century that the procedure gained widespread appreciation and evolved into its current identity. Initially, the procedure was described as using a strip of mobilized abdominal muscle (either rectus or pyramidalis). One end of the strip was freed from its attachment, passed under the bladder neck, and then reaffixed to the abdominal muscle wall, thus forming a “U”-shaped sling of muscle tissue around the bladder outlet. Subsequently, overlying abdominal fascia was included in the sling, and eventually replaced the muscle altogether. In 1942, Aldridge reported his fascial suburethral sling procedure, which is the forerunner of the modern pubovaginal sling. Aldridge described the procedure as a salvage-type operation for those women who had failed previous operations for stress incontinence. For the sling, he used rectus fascial strips that remained attached to the anterior abdominal wall and were passed bilaterally along the urethra and sutured together under the bladder neck. The final innovation involved using an isolated strip of fascia suspended by free sutures that were then tied to the abdominal wall directly or on top of the abdominal rectus sheath.
Despite its roots as an autologous procedure, many different types of materials have been used as sling substitutions, including various sources of autologous tissue, allografts, xenografts, and synthetic materials. Almost all these attempts at substitution have been made to help limit patient morbidity, as the procedure requires the additional morbidity of a sling tissue harvest site. Nevertheless, the most popular variety of the pubovaginal sling remains associated with the use of autologous rectus abdominis fascia.
Regardless of the material used, the pubovaginal sling is meant to be placed at the proximal urethra and bladder neck. The concept of the autologous pubovaginal sling involves supporting the proximal urethra and bladder neck with a piece of graft material, achieving continence either by providing a direct compressive force on the urethra/bladder outlet or by reestablishing a reinforcing platform or hammock against which the urethra is compressed during increased abdominal pressure. The sling is suspended with free sutures on each end that are either attached directly to the abdominal wall musculature or tied to each other on the anterior surface of the abdominal wall. The long-term success of the procedure relies not on the integrity of the suspensory sutures, but rather on the healing and fibrotic process involving the sling, which occurs primarily where the sling passes through the endopelvic fascia.
The pubovaginal sling is a surgical option for both primary and recurrent stress urinary incontinence (SUI). Although pioneered as a surgical treatment for intrinsic sphincter deficiency (ISD), its indications have been broadened to encompass all types of SUI. Because of its reliable results and durable outcomes, it is one of the main standards of treatment of SUI and has been used extensively as a primary therapy for SUI (both for ISD and urethral hypermobility), as a salvage procedure for recurrent SUI, as an adjunct for urethral and bladder reconstruction, and even as a way to functionally “close” the urethra to abandon urethral access to the bladder altogether. Another indication is in patients with SUI who decline to have a synthetic material implanted because of long-term concerns related to synthetic mesh. Also, women who have recurrent incontinence or experience a complication after implantation of a synthetic sling (such as vaginal erosion) may be good candidates for the autologous fascial sling. Finally, we prefer to use an autologous sling in patients who have been irradiated, who have had urethral injuries, and who are undergoing either simultaneous or prior urethrovaginal fistula or diverticulum repair.
With the increasing popularity of primary sling procedures, the escalating demand for minimally invasive techniques, and the need for nonmesh options, numerous materials have become available for use in suburethral slings. Current biologic materials can be categorized as autologous fascia, allograft fascia, or xenograft fascia. Within these categories, different variants can be subgrouped into individual materials: autologous (rectus fascia, fascia lata, vaginal wall), allograft (freeze-dried irradiated cadaveric fascia lata, solvent dehydrated cadaveric fascia lata, fresh frozen cadaveric fascia lata, cadaveric dermis), and xenograft (porcine dermis, porcine intestinal submucosa) which has been used historically but is no longer commercially available. Autologous rectus fascia and fascia lata are the most common materials in use, and the standard to which the outcome of other new materials should be compared. Both have been studied extensively and have proven to be efficacious and reliable. Of the two, most surgeons prefer rectus fascia as an autologous material because it is easier and quicker to harvest.
The application of newer tissue harvesting technologies has made multiple human- and animal-based materials available. The theoretical rationale for using allografts and xenografts for suburethral slings is reinforcement of inherently weak endopelvic fascia. Allogenic grafts harvested from cadaveric donors are widely used and do not seem to carry a significant risk of erosion or infection. Cadaveric fascia lata and cadaveric dermis provide reasonable efficacy, although durability remains an issue because higher failure rates compared with allogenic grafts have been reported in some studies. The long-term durability of allograft fascia continues to be studied, and there seems to be wide variability in the quality of tissue, depending on its source and processing. The type of sling material probably does not significantly affect cure rates, provided that the characteristics of the chosen material are considered carefully, however it may affect durability.
Synthetic graft materials of various designs and substances have been used as sling material. As with other types of synthetic graft materials, monofilament, large-pore weave grafts (type I mesh) are recommended for implantation in the vagina. Good efficacy can be achieved with synthetic mesh; although synthetic mesh also poses risks of unique complications, including infection, vaginal extrusion, and genitourinary erosion. Thus, synthetic slings are currently not usually recommended for use underneath the proximal urethra or bladder neck.
Rectus fascia pubovaginal sling
We recommend starting vaginal estrogen in postmenopausal women with vaginal atrophy at least 4 to 6 weeks before surgery. Tissue integrity improves with estrogen, and this may provide clinical benefits to the patient. No studies, however, have shown improved outcomes by using estrogen before and/or after prolapse or incontinence surgery. Informed consent should be methodical; it is a process rather than a single event. In addition to discussing the usual risks encountered in a major operation (infection, hemorrhage, injury to adjacent organs, and medical and anesthesia complications), a frank conversation should take place regarding the expected outcomes, the likelihood of SUI recurrence, the potential of voiding dysfunction, and the risk of prolonged catheterization. Additionally, because the use of a fascial (or other) graft is planned, delineating the unique set of risks related to these procedures is prudent.
Pubovaginal sling procedures are generally carried out with the patient under general anesthesia, but spinal or epidural anesthesia is also possible. Full patient paralysis is not warranted but may facilitate rectus fascia closure after fascial harvest. Perioperative antibiotics are administered with appropriate skin and vaginal floral coverage (e.g., a cephalosporin). Antibiotics should be given within 60 minutes of incision to achieve minimal inhibitory concentrations in the skin and tissues by the time the incision is made. This has now become a mandated quality-of-care measure in the United States.
In general, all patients undergoing vaginal surgery are at moderate risk for thromboembolic events and require a prevention strategy. Low-dose unfractionated heparin (5000 units every 12 hours) or low-molecular-weight heparins (e.g., 40 mg enoxaparin or 2500 units of dalteparin), an intermittent pneumatic compression device, or a combination of these are recommended. Either form of heparin should be started 2 hours before surgery, and the compression stockings placed on the patient in the operating room before incision. These treatment approaches should be continued until the patient is ambulatory.
The patient is placed in the low lithotomy position with legs in stirrups, and the abdomen and perineum are sterilely prepared and draped to provide access to the vagina and the lower abdomen. The bladder is drained with a Foley catheter. A weighted vaginal speculum is placed, and either lateral labial retraction sutures or a self-retaining retractor system are used to facilitate vaginal exposure.
Abdominal incision and fascial harvest.
An 8- to 10-cm Pfannenstiel incision is made (approximately 3–5 cm above the pubic bone), and the dissection is carried down to the level of the rectus fascia with a combination of electrocautery and blunt dissection, sweeping the fat and subcutaneous tissue clear of the fascia ( Fig. 16.1 ).
Harvest of the rectus abdominis fascia can be carried out in a transverse or vertical orientation. Typically, a fascial segment measuring at least 8 cm in length and 1.5 to 2 cm in width is harvested. The fascial segment to be resected is delineated with a surgical marking pen or electrocautery, and then incised sharply with a scalpel, scissors, or electrocautery along the drawn lines. Although virgin fascia is preferred, the presence of fibrotic rectus fascia does not prohibit its use. If resecting the fascia close and parallel to the symphysis pubis, it is advisable to leave at least 1 cm attached, so as to facilitate closure and approximation to the superior fascial edge. Use of small Army/Navy retractors permit retraction of skin edges, thus allowing access through a smaller skin incision ( Fig. 16.2 ).
To prepare the fascial sling for use, a No. 1 permanent (e.g., polypropylene) suture is affixed to each end using a running stitch to secure the suture to the sling. Defatting of the sling may be done if necessary ( Fig. 16.3 ).
The fascial defect is closed using a heavy-gauge (No. 1 or 0) delayed absorbable suture in a running fashion. Mobilization of the rectus abdominis fascial edges may be required to ensure appropriate tension-free approximation. It is important to ensure that adequate anesthesia with muscular relaxation/paralysis is present when the closure is being done. Although cellulitis and hematomas are uncommon, meticulous hemostasis and copious wound irrigation are done before skin closure.
Vaginal dissection proceeds with a midline or inverted “U” incision. Injectable saline or local analgesic, such as 1% lidocaine, may be used to hydrodissect the subepithelial tissues. Vaginal flaps are created with sufficient mobility so as to ensure tension-free closure over the sling. Dissection is carried laterally and anteriorly until the endopelvic fascia is encountered. The endopelvic fascia is incised and dissected from the posterior surface of the pubis to enter the retropubic space. This dissection can, at times, be done bluntly, but often, especially in recurrent cases, requires sharp dissection with Mayo scissors ( Fig. 16.4 ). To penetrate this fascia, the tips of the scissors should advance toward the ipsilateral shoulder, staying in direct contact with the posterior surface of the pubic bone.