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Treating stress urinary incontinence with suburethral slings

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Recent modifications to suburethral sling procedures have brought them to the forefront of stress urinary incontinence treatment. Here, the authors review the advances and evidence on synthetic and organic slings.


 

References

KEY POINTS
  • Suburethral sling procedures are effective in treating patients with urethral hypermobility, intrinsic sphincter deficiency, low-pressure urethras, and increased intra-abdominal pressure.
  • Autologous slings may be a better choice in cases of severe urogenital atrophy, previous radiation, or extensive scarring from previous repairs.
  • For both the tension-free vaginal tape and SPARC slings, mark the suprapubic region 1 cm above and 1 cm lateral to the pubic symphsis on the left and right sides and inject 20 cc of a 1:1 mixture of local anesthetic and normal saline into the marked regions.
  • Once the trocars are in place, fill the bladder with 250 cc of water and perform a cough stress test to confirm continence.

When the suburethral sling was first described in 1907 by von Giordano, it entailed placing autologous tissue underneath the bladder neck and suspending it superiorly. Complications including urethral erosion, infection, bleeding, and fistula formation led many surgeons to use it sparingly.

Fast forward to the 21st century: Synthetic materials and new techniques were introduced, simplifying the sling procedures and raising the long-term success rates to 84%.1 As a result, slings now stand at the forefront of stress urinary incontinence (SUI) treatment. Among advances are the tension-free vaginal tape (TVT) sling (Gynecare, a division of Ethicon Inc., Somerville, NJ) and the SPARC sling (American Medical Systems, Inc., Minnetonka, Minn). The former, approved in the U.S. in 1998, calls for another look due to of the recent publication of a Cochrane review of outcomes studies, while the latter, approved by the FDA in August 2001, is the newest technique deserving examination. Clearly, with 83,010 incontinence procedures performed in the U.S. in 1999,2 a detailed look at the suburethral sling is warranted. Here, we review materials, indications, techniques, complications, and outcomes.

Materials

The choice of material—either organic or synthetic—depends on several factors: availability, cost, patient and surgeon preference, and clinical variables. (TABLE 1) outlines the advantages and disadvantages of each material type. Organic slings include autologous tissues (rectus fascia and fascia lata graft), and allografts or xenografts (cadaveric fascia lata graft, human dermal graft, or porcine small intestine and dermal graft). Synthetic slings are made of polyethylene terephthalate, expanded polytetrafluoroethylene, and polypropylene.

While sling procedures utilizing organic materials do have their benefits, synthetic slings, particularly the polypropylene mesh used in TVT and SPARC, have proven to be a stable material unlikely to deteriorate with time. Further, increased collagen metabolism around this synthetic sling promotes an ingrowth of tissue through the mesh.

TABLE 1

Slings: advantages and disadvantages of various materials

SLING MATERIALADVANTAGESDISADVANTAGES
Autologous tissues (rectus fascia, fascia lata, or vaginal wall)
  • Patient’s own tissue is less likely to be rejected or become infected
  • Prolongs operation due to time for graft harvesting
  • Increased pain related to harvesting incision
  • Fascia may have inconsistent strength and size
  • May predispose to hernia formation (rectus fascia)
Allografts (cadaveric fascia lata or dermis)
  • No harvesting required, therefore shorter operating time and less patient discomfort
  • Cost
  • Potential for sling failure due to graft autolysis from host vs graft rejection or poor uniform tissue quality
  • Lack of long-term data
Xenografts (porcine dermis or small intestine)
Synthetic mesh (polyethylene terephthalate, expanded polytetrafluoroethylene, or polypropylene)
  • No harvesting required
  • Consistent strength
  • Less patient discomfort
  • Cost
  • Risk of infection, rejection, and erosion

Indications

Suburethral sling procedures are typically used for the treatment of genuine stress urinary incontinence (GSUI), in which the urethra becomes either hypermobile and unstable or its intrinsic sphincter becomes incompetent. In fact, slings are technically easier to place in patients with anatomic urethrovesical junction hypermobility compared to those with fixed urethras. Several authors also have suggested the sling’s advantage in patients with low-pressure urethras.3

Use urodynamic criteria to diagnose intrinsic sphincter deficiency (ISD), which is defined as a Valsalva leak point pressure of less than 60 cm water or maximal urethral closure pressure of less than 20 cm water. (Bear in mind, however, that these cut-off criteria are controversial.4,5)

Also, consider slings in patients with recurrent GSUI, inherited collagen deficiency, and increased abdominal pressure (e.g., women with chronic obstructive pulmonary disease, obesity, or high-impact physical activity). The sling also can be used as an adjunct to other transvaginal surgeries (e.g., hysterectomy or prolapse repair).

Autologous slings may be a better choice than synthetic slings in cases of severe urogenital atrophy, previous radiation, or extensive scarring from previous repairs. In these instances, the patient may be at-risk for postoperative vaginal necrosis or erosion.6 Due to their biocompatibility, autologous slings are more likely to heal over a vaginal erosion and less likely to infect or erode into the urethra. In any event, urogenital atrophy should be treated with local estrogen preoperatively to prevent some of these complications.

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