Currently, suburethral sling procedures can be broadly classified into bladder neck and midurethral slings (Box 16-1; Fig. 16-1). Slings can be made of a biologic material and are placed at the level of the proximal urethra and bladder neck or a synthetic material placed either under the proximal or midurethra. The currently used biologic materials are divided into autologous tissue, which is harvested from the patient who is undergoing the sling; allograft material, which is most commonly cadaveric fascia lata; or xenografts, which are harvested from various animal sources. Proximal urethral slings are called pubovaginal slings when the arms of the material used are connected to the anterior rectus fascia on each side.

Figure 16-1 Cross-sectional view of suburethral sling modifications. A. Traditional pubovaginal sling. B. Modified patch sling, in which ends of sling do not enter the retropubic space. C. Patch sling, in which ends of sling are in the retropubic space. D. Patch sling, in which sutures are anchored into bone. E. Patch sling that is anchored directly into bone. F. In situ vaginal wall sling. G. Synthetic midurethral retropubic sling. H. Synthetic midurethral transobturator sling.

Various modifications of a traditional pubovaginal sling have been described and involve various patch-type slings in which the sling materials are placed vaginally at the level of the proximal urethra and then attached to sutures that are passed suprapubically. Some surgeons believe in the importance of the arms of the sling penetrating the urogenital diaphragm and entering the retropubic space, whereas others feel that this is not necessary. Another type of proximal urethral sling is the in situ vaginal wall sling, in which an anterior vaginal wall patch under the proximal urethra is suspended to the anterior abdominal fascia via permanent bridging sutures.

The TVT procedure was the first synthetic midurethral sling and was described by Petros and Ulmsten (1990), 1995). This ambulatory procedure was aimed at restoring the pubourethral ligament and suburethral vaginal hammock by using specially designed needles attached to a synthetic sling material. The synthetic sling material is made of polypropylene and is approximately 1 cm wide and 40 cm long. The sling material is attached to two stainless steel needles that are passed blindly from a vaginal incision made at the level of the midurethra through the retropubic space to exit at previously created stab wounds in the suprapubic area.

After this midurethral sling became well-established, techniques to surgically correct stress incontinences via a suprapubic approach were described (SPARC procedure [American Medical Systems, Minnetonka, MN]; percutaneous vaginal tape [PVT]). This involved passage of a needle from the suprapubic area to exit in a previously created incision in the vagina of the level of the midurethra. These procedures quickly became popular and were shown to be efficacious. Because they did require blind passage of the needle through the retropubic space, rare but serious complications were reported in the form of vascular and bowel injuries. These complications resulted in significant morbidity and rare cases of mortality.

Delorme (2001) reported on the first transobturator synthetic midurethral sling and described that the passage of the needle completely avoided the retropubic space and avoided any potential for serious complications in the form of vascular or bowel injuries as well as the potential for injury to the lower urinary tract. The initial description of this procedure involved the passage of specially designed needles from the obturator region, through the obturator membrane, around the ischiopubic ramus to exit in the open portion of the vagina. Shortly after the initial description, a procedure that involved passage of the needle from the vaginal incision to exit the obturator space was described.

TECHNIQUES OF SUBURETHRAL SLING PROCEDURES

Proximal Suburethral Sling and Modifications

The optimal route and surgical technique of a suburethral sling procedure placed beneath the proximal urethra and bladder neck must be considered preoperatively. Most surgeons perform a pubovaginal sling procedure via a combined abdominal and vaginal route, with the majority of the dissection being done vaginally. The procedure can also be performed entirely via abdominal approach, with tunneling of the sling between the urethra and the vagina. However, this approach increases the likelihood of urethral trauma and is currently rarely used. More recently, sling procedures have been performed through an entirely vaginal route through which the sling material is either anchored to the back of the pubic bone or sutured into Cooper’s ligament via a special needle ligature passage. The choice of sling material, approach, and operative technique is at the discretion of the surgeon. To date, no randomized trial has compared these various modifications and sling materials.

If the surgeon decides to use autologous tissue, it will most commonly be either fascia lata or rectus fascia. Harvesting of these tissues is usually performed before any vaginal dissection. The technique of harvesting fascia lata is determined by whether the surgeon prefers to do a complete pubovaginal sling, or whether a patch-type sling is performed. The fascia lata graft is usually approximately 4 × 6 cm in diameter. This can be obtained via a 3- to 4-cm transverse skin incision made approximately 8 cm above the midpatella, lateral to the knee and the lower thigh. Blunt dissection exposes the underlying fascial lata, and a piece of fascia is easily removed to serve as the patch for the sling procedure. Subcutaneous tissue is reapproximated, the skin is closed, and a pressure bandage is placed. If a full pubovaginal sling is used, a long piece of fascial lata can be obtained using a Wilson or Crawford fascial stripper. The technique for obtaining the full strip of fascia involves a blunt dissection of the fat away from the fascia lata all the way up the lateral side of the leg toward the greater trochanter. A 1-cm wide piece of fascia is usually removed using the fascial stripper. This will result in a 20-cm long piece of fascia. If a longer piece of fascia is desired, a second piece of fascia of a similar length can be obtained by repeating the same procedure. When this is performed, there should be a 1-cm wide area of fascia lata that remains between the two areas where the stripper has removed the tissue. In either case, closure of the fascia defect is not necessary.

The other autologous tissue that is commonly used for pubovaginal sling is the fascia of the anterior abdominal wall of the anterior rectus fascia. To obtain this fascia, a low transverse abdominal incision is made approximately 4 cm above the pubic symphysis. Blunt dissection is performed in the subcutaneous tissues until the rectus fascia is visualized. An appropriately sized piece of rectus fascia is harvested in the transverse direction using sharp dissection or electrocautery. The size of the strip is usually approximately 1 cm wide and 20 cm long. The fascial incision is closed using No. 0 delayed absorbable sutures, and the abdominal incision is packed until the vaginal portion of the procedure is completed.

The operative details for suburethral pubovaginal sling placed at the level of the proximal urethra are as follows:

1. The patient is placed in high stirrups in the dorsal lithotomy position and the vagina and lower abdomen are appropriately prepped and draped. Preoperative antibiotics are usually given on call to the operating room.

2. Hydrodissection of the anterior vaginal wall is usually used by injecting beneath the epithelium of the anterior vaginal wall at the level of the bladder neck. This facilitates dissection of the appropriate plane and may also have a hemostatic effect.

3. A midline vaginal incision or an inverted U vaginal incision is made at the level of the proximal urethra or bladder neck, which is easily determined by palpation of the anterior vaginal wall with a Foley catheter in place. The vaginal epithelium is carefully dissected off the underlying periurethral and perivesical fascia, using blunt and sharp dissection. This dissection is extended bilaterally to the inferior lateral aspects of the pubic rami.

4. The retropubic space is entered, using either blunt or sharp dissection (Fig. 16-2). Once the periurethral attachment of the urethra and the urogenital diaphragm has been penetrated on each side, one should be able to pass a finger along the backside of the pubic bone all the way to the inferior aspect of the rectus muscle.

5. If a traditional pubovaginal sling is to be performed, an abdominal incision is made at this time. The incision is usually made approximately 2 fingerbreadths or 4 cm above the level of the pubic symphysis, and is a transverse incision usually no more than 8 cm long. The incision is extended down to the rectus fascia.

6. The sling is brought into the field and is transferred from the vaginal incision, through the retropubic space, to above the anterior abdominal fascia. Each arm is transferred, using either a dressing forceps or some type of needle ligature carrier. Small incisions in the fascia allow each arm to come up through the fascia. The transfer of each arm of the sling is done under direct finger guidance. A full length pubovaginal sling should loosely sit at the level of the proximal urethra and is usually anchored there with several fine absorbable sutures (Fig. 16-3).

7. If a patch-type sling is used, the length of the patch is determined and the longitudinal edges of the patch are attached to permanent sutures and these sutures are passed into the anterior abdominal incision (Fig. 16-4). Bone fixation techniques can be done in which sutures, or the sling itself, are directly anchored into bone.

8. Cystourethroscopy is performed to ensure no inadvertent injury or passage of any material through the bladder. Also, visualization of the proximal urethra and bladder neck documents that the sling is in the appropriate position. Elevation on the arms of the sling or the sutures should elevate the level of the proximal urethra. If there is no mobility at this area, the sling is either placed in the wrong anatomic position or further periurethral dissection needs to be performed to create urethral mobility.

9. The final step involves appropriate tensioning of the sling. Unfortunately, no standardized method exists that can be used on all patients. One must individualize the patient based on the severity of her incontinence and the state of her pelvic tissue. In general, the sling should be placed loosely at the level of the proximal urethra and should act as a backboard to prevent descent of the proximal urethra during increases in intra-abdominal pressure. Thus, after tying of the sling, downward traction on a Foley catheter should document that this area has been appropriately supported with the previously mentioned backboard mechanism. The authors routinely place a right-angle clamp between the urethra and the sling material during tying, with the goal of maintaining zero tension at rest. A compressive mechanism of a suburethral sling ideally should be activated only during increases in abdominal pressure.

10. After the sutures are tied, the anterior vaginal wall is closed, and a transurethral or suprapubic catheter is left in place. A vaginal packing is also commonly used.

Figure 16-2 A. Technique of blunt dissection into retropubic space. With tip of index finger flexed anteriorly against posterior symphysis, periurethral attachment to pubic bone is perforated, completely detaching endopelvic fascia. B. Technique of vaginal entrance using Metzenbaum scissors; endopelvic fascia is perforated at inferior margin of pubic bone, as guided by surgeon’s index finger. Blades of scissors are separated, and dissection is completed by inserting a finger into space created, as shown in A.

Figure 16-3 Full-length suburethral sling, in which fascia or synthetic material is passed and tied above the anterior rectus fascia.

Figure 16-4 Patch sling using combined needle suspension sling procedure, in which a suburethral patch of fascia or synthetic material is suspended to the anterior rectus fascia with permanent sutures.

Synthetic Retropubic Midurethral Slings

TVT

The patient is brought to the operating room and one of general, regional, or local anesthesia with sedation is administered. Broad-spectrum preoperative antibiotics, such as cephazolin, should be used. The patient is positioned in the dorsal lithotomy position. The authors prefer to use candy-cane stirrups for this. Patients should be in the horizontal or in slight Trendelenburg position to displace bowel away from the pelvis.

The instrumentation required for the procedure includes 30 mL of local anesthetic, such as lidocaine or Marcaine; a 22-gauge needle for infiltration; TVT kit (Fig. 16-5 [Ethicon Inc., Somerville, NJ]), which includes two 5-mm stainless steel needles connected by a 1.2-cm wide piece of polypropylene mesh; a nondisposable handle or introducer; an 18-French Foley catheter; catheter guide; and absorbable sutures to close the incisions.

Figure 16-5 Tension-free vaginal tape instrumentation, including (clockwise from top) a Foley catheter guide, needle introducer/handle, and specially designed needles attached to a synthetic suburethral sling tape.

(Courtesy of Ethicon Inc., Somerville, NJ.)

Using a pen, the surgeon outlines the sites of the suprapubic stab incisions. These should be along the superior rim of the pubic bone, 2 fingerbreadths lateral to the midline, 0.5- to 1-cm long. The two suprapubic puncture sites should be anesthetized with local anesthesia. We prefer to use 1% lidocaine with epinephrine, 10 mL on each side. The injection should be taken down to the pubic bone to infiltrate the rectus fascia and muscle.

An 18-French Foley catheter should be placed and the bladder drained. A Sims or weighted speculum is placed in the vagina. Local anesthesia (8 to 10 mL) is infiltrated in the anterior vaginal wall to achieve hydrodissection and vasoconstriction. A 1.5-cm midline incision is then made at the midurethra, as shown in Figure 16-10, A. Palpating the Foley bulb at the bladder neck may be helpful to ensure that the incision is appropriately placed. With Allis clamps stabilizing the vaginal mucosa, the Metzenbaum scissors are used to dissect under the vaginal epithelium laterally to create a tunnel to the inferior pubic ramus. Unlike the bladder neck, at the midurethra the anterior vaginal wall and posterior urethra are fused and no natural plane of dissection is present. Hence, one must minimize creation of these tunnels to ensure that the tape stays in the proper position.