[ Editorials | Letters | Selected Articles | Signature Series | Patient Handouts | Index ]

2002 Selected Articles

Suburethral Sling Complications: Recognition and Management

Peter L. Rosenblatt, MD; Charles R. Rardin, MD; Neeraj Kohli, MD

It has been estimated that urinary incontinence affects 10% to 25% of the adult US female population under the age of 65,¹and up to 40% of community-dwelling women aged 65 years or more.²Stress incontinence (ie, leakage of urine with sudden increases in intraabdominal pressure) occurs in approximately 6 million Americans. Over the past decade, there has been a growing interest in innovative conservative and surgical methods to treat female stress urinary incontinence. Some 150,000 surgical procedures are performed annually in the United States for stress incontinence, although this accounts for only 2% of the population with this condition.³

PATHOPHYSIOLOGY

The most common form of stress urinary incontinence, genuine stress incontinence (GSI), is due to an anatomic defect in the endopelvic fascia under the bladder neck, resulting in urethral hypermobility. Detrusor instability (DI), or involuntary contraction of the detrusor muscle, is the second most common cause of urinary incontinence in women. A smaller but significant number of women with symptoms of severe stress incontinence are found to have intrinsic sphincter deficiency (ISD). This condition is most often seen in older women and in those who have undergone multiple surgical procedures for the treatment of stress urinary incontinence. In this setting, ISD may result from scarring or denervation of the urethral sphincter. This compromised sphincter cannot maintain a water-tight seal at rest, resulting in the classic "lead-pipe" urethra. Other risk factors for ISD include pelvic x-ray therapy, radical pelvic surgery, and neurologic conditions such as spinal cord injury or meningomyelocele.

Based on symptoms alone, it is easy to confuse ISD with both GSI due to urethral hypermobility (stress incontinence symptoms) and DI (large-volume urine loss). These conditions can be differentiated through a careful history, physical examination, and specialized urodynamic testing. Accurate diagnosis of ISD is essential because its treatment is considerably different from that of either GSI with urethral hypermobility or detrusor instability.

SUBURETHRAL SLING

Von Giordano introduced the suburethral sling in 1907, using gracilis muscle flaps sutured beneath the urethra.⁴This was among the first descriptions of a surgical procedure for stress incontinence. Since then, more than 150 different antiincontinence procedures have been formally described. Most of these can be grouped into four general categories: anterior colporrhaphy, retropubic urethropexy (eg, Burch, Marshall-Marchetti-Krantz), transvaginal needle suspension (eg, Pereyra, Raz) and suburethral sling. In 1997, a panel of the American Urological Association published clinical guidelines for the management of female GSI.⁵They concluded that, after 48 months, retropubic suspensions and suburethral slings appear to be more efficacious than either transvaginal suspensions or anterior repairs (Table 1).^5,6Because several studies have suggested that slings are associated with higher complication rates, most US urogynecologists consider the Burch retropubic urethropexy to be the "gold standard" for GSI surgery.

Women diagnosed with ISD pose a special challenge, however, because retropubic urethropexy has a high failure rate in these cases. In a retrospective study of 83 women, Sand found that patients with a preoperative maximum urethral closure pressure (MUCP) below 20 cm H₂O had a 54% failure rate following Burch colposuspension compared with an 18% failure rate for women with an MUCP greater than 20 cm H₂O.⁷In treating women with ISD, providing partial obstruction of the urethra (rather than simply stabilizing the urethrovesical junction) seems to be more effective. For this reason, suburethral slings have traditionally been used to treat ISD.

Women with recurrent stress incontinence (ie, those who have failed surgery) and those who lead very active lifestyles or whose careers require heavy lifting may also be candidates for sling procedures. Over time, repetitive stress may pull out sutures and weaken the support from a Burch procedure or other retropubic suspension. Additionally, women with medical problems leading to chronically increased intraabdominal pressure (eg, chronic obstructive pulmonary disorder, asthma, obesity) may be at risk for failing standard antiincontinence procedures. Therefore, these women are probably best treated with suburethral sling surgery.

Because slings have such a high cure rate (81% to 98% in the literature), some authorities recommend that suburethral slings be used to treat all stress incontinence, regardless of subtype.⁸Moreover, it has been suggested that as many women with urethral hypermobility do not have stress incontinence, there must be some degree of intrinsic sphincter incompetence in all women with stress incontinence, even when urodynamic parameters fail to suggest ISD as the diagnosis.⁹In this situation, a sling would provide the suburethral support and closure required for continence. Although it is widely believed that slings are associated with higher complication rates compared with retropubic urethropexies, these studies are biased in favor of retropubic suspensions, which are often performed on younger women or less complex cases (eg, no previous bladder-neck surgery).

With proliferating indications for the use of suburethral slings as well as the increasing use of surgery as a first-line therapy for stress incontinence, it is likely that the number of sling procedures will rise substantially over the next few decades. It is essential that all clinicians who care for women be aware of these procedures and their potential complications to promote early recognition and effective management of these problems.

Complications can be divided into those that are common to any incontinence procedure (eg, injury to the urinary tract, wound or urinary tract infection, retropubic hematoma, persistent incontinence) and those that are either specific to or more prevalent in suburethral sling procedures (eg, erosions, prolonged urinary retention, voiding dysfunction, new-onset detrusor instability).

Types of Slings

Since its introduction almost a century ago, the techniques used for suburethral slings have undergone numerous modifications, including variations in the material used for the sling and the methods and points of attachment for the sling arms. The development of postoperative complications seems to depend primarily on the selection of sling material. Autologous (eg, rectus fascia, fascia lata), homologous (eg, cadaveric fascia, dermal allograft), heterologous (eg, porcine intestinal submucosa) and synthetic materials have all been used as grafts for suburethral slings.

The use of autologous organic tissues (fascia lata, rectus fascia) continues to be appealing from the standpoint of biocompatibility. However, the extra surgery required to harvest this tissue is associated with increased operative time, pain from separate or enlarged surgical incisions, and higher rates of complications and morbidity.¹⁰

To overcome these issues, many surgeons use banked cadaveric tissues for slings. These allograft materials are readily available, do not require intraoperative harvesting, and are specially processed to reduce tissue reactivity. On the other hand, fascial allografts may be associated with decreased success rates due to inconsistent strength and/or weakening of the tissue over time. Chaiken and Blaivas¹¹describe a case of immediate sling failure attributed to suture pull-through at both ends of the fascial sling allograft. FitzGerald and colleagues¹²describe a 12% short-term failure rate associated with cadaveric fascia lata; on reoperation, graft tissue was either "absent" or markedly attenuated in all cases. Histologic studies confirmed their surgical findings. Of note, most of the studies on the problems with cadaveric materials have involved the use of fascia. More recently, though, dermal grafts have been used for slings and other pelvic reconstructive procedures, and may represent a promising alternative to fascia.

Since the 1950s, a variety of synthetic materials (eg, Marlex mesh, Mersilene mesh, Prolene mesh, Silastic, Gore-Tex) have been used for suburethral slings. The use of synthetic materials has several advantages, including uniform sling strength and decreased morbidity and operative time compared with harvesting autologous grafts, but may cause erosion over time.

COMPLICATIONS

Sling Erosion

Compared with cadaveric tissue, synthetic slings are associated with higher rates of erosion and infection. The Female Stress Urinary Incontinence Clinical Guidelines Panel of the American Urological Association observed that the use of synthetic material for slings is associated with an increased complication rate, including vaginal and urethral erosions and wound sinus formation.⁵The risk of these complications depends on the particular material used, although certainly surgical technique plays a role as well. While Gore-Tex slings have been associated with a high rate of erosion, requiring removal of the sling in up to 22% of patients,¹³other synthetics (eg, Mersilene mesh) confer a significantly lower risk of vaginal erosion. In a study of 110 women who underwent suburethral sling placement using Mersilene mesh, only one patient (0.9%) required excision of an eroded sling.¹⁴Although the Clinical Guidelines Panel reported that these complications occurred at rates below 1% (excluding certain high-risk synthetics), they can be troubling to patient and physician alike. Overall, serious complications arising from sling erosion into the bladder or urethra are rare. Sling erosions may occur early in the postoperative period, with the vaginal wall failing to heal over the sling due to extensive dissection, local devascularization, or sling infection. Delayed erosions have also been reported in some series, with patients presenting up to 3.5 years after sling placement.

Women with vaginal sling erosions may present with persistent or new-onset vaginal discharge, bleeding (spontaneous or postcoital), dyspareunia, or vaginal pain. Careful examination of the anterior vaginal wall in the vicinity of the bladder neck may reveal the presence of granulation tissue, a sinus tract, or the sling itself eroded through the mucosa. Colposcopic evaluation may be useful for visualizing vaginal erosions. In the rare case of sling erosion into the bladder or urethra, patients may present with recurrent urinary tract infections, hematuria, or irritative voiding symptoms. Although bladder and urethral erosions have been reported most commonly with synthetic slings,¹⁵they may also occur with fascial slings, and should be considered when women present with repeated urinary retention or irritative symptoms.¹⁶Cystoscopy should be performed if these symptoms are persistent, even if the test results were normal at the time of the surgery.

The difficulty of sling removal largely depends on the material used. Silastic and Gore-Tex are generally easy to remove, while Mersilene mesh may be more difficult or even impossible to remove completely because of extensive tissue ingrowth. Small vaginal sling erosions (less than 5 mm) that do not appear to be infected may respond to conservative treatment with topical estrogen alone, or with trimming of the visible sling and cauterization of granulation tissue. Larger erosions may be treated with excision of the exposed sling and reapproximation of healthy vaginal wall flaps (created by undermining the epithelium) with absorbable suture.¹⁷

In 1997, a woven polyester sling treated with pressure-injected bovine collagen (ProteGen) was introduced as part of a surgical kit for stress incontinence. Kobashi and associates¹⁸reported on 34 women who required removal of the ProteGen polyester sling after the onset of erosion, infection, or pain. The most common presenting symptoms were delayed vaginal discharge, vaginal pain or pressure, suprapubic pain, and recurrent urinary tract infection. These women presented an average of 8 months after sling placement (range of 1 to 22 months). In this report of complications, 50% of patients had vaginal erosion of the sling. Less common presenting problems were urethral erosion (20%), urethrovaginal fistula (17%), and vaginal sinus tract (0.3%). It should be noted that as this is simply a report on a group of complications, it is impossible to determine the true incidence of these problems. The ProteGen sling was voluntarily recalled by the manufacturer in 1999.

Because vaginal erosions may occur a year or more after sling placement, concern has been raised about delayed diagnosis of this complication. Women presenting to their gynecologists with abnormal vaginal bleeding or discharge may undergo evaluation with endometrial biopsy, dilation and curettage, or hysteroscopy. Others may be treated with multiple courses of hormonal or antibiotic preparations. Failure to consider sling erosion as a cause of vaginal bleeding, discharge, or pain or of dyspareunia may subject women to unnecessary and invasive investigations. Delayed or incorrect diagnosis can be a source of frustration for women who experience an erosion of synthetic mesh into the vagina.

More recently, tension-free vaginal tape, TVT, has gained popularity as a minimally invasive sling procedure that uses Prolene mesh to support the midurethra. Although long-term data regarding TVT are lacking, few vaginal erosions have been reported, which may in part be a function of the minimal dissection (and resultant minimal devascularization) required to properly place the sling.

Irritative Symptoms

The effect of suburethral slings on preexisting urinary urge symptoms is variable and unpredictable. Some women experience resolution of urgency or urge incontinence after surgery, while others may have persistent irritative symptoms.¹⁹In general, women with mixed incontinence (GSI associated with DI) should be treated conservatively, with surgery considered only after resolution or improvement of urgency. In addition, some women may develop de novo irritative voiding symptoms, eg, urgency, frequency, urge incontinence, following sling procedures. This may represent the bladder’s response to increased outlet resistance. In any event, the prevalence of irritative symptoms decreases from 40% to 50% 1 week after surgery to 10% at 10 weeks.²⁰Patients should therefore be reassured that these symptoms usually resolve over time. If treatment is required, postoperative DI usually responds well to anticholinergic agents and bladder retraining drills.

Voiding Dysfunction

Suburethral slings are associated with a higher risk of postoperative voiding problems than other operations for stress incontinence.⁵The most common cause of voiding dysfunction from sling procedures is excess tension on the sling or its suspending sutures, which results in bladder outlet obstruction and the myriad problems that follow. These include elevated postvoid residual volumes, hesitancy, decreased urinary stream, irritative symptoms, and urinary retention.

Successful management of postoperative voiding dysfunction begins with proper preoperative consent. All women undergoing antiincontinence surgery should be counseled regarding the risk of voiding problems. While suburethral sling procedures appear to offer the highest success rates (particularly for women with ISD), they also appear to have the highest risk of postoperative voiding dysfunction. Women who are candidates for sling procedures must understand before surgery that voiding problems may not be resolved by sling placement. By the same token, however, they should be encouraged not to view voiding dysfunction as a sign of therapeutic failure.

The first potential voiding complication likely to be encountered by a patient after placement of a suburethral sling is incomplete bladder emptying. The bladder, having grown accustomed to decreased outlet obstruction, is frequently unable to generate enough pressure to open the newly suspended urethra, particularly in light of perioperative swelling and tissue trauma. Postoperative voiding trials may demonstrate complete retention or high postvoid residual volumes; even patients who have successful voiding trials after surgery may present later with urinary retention. These patients should be provided with some form of bladder drainage until bladder function is recovered.

Continuous transurethral drainage (Foley catheter) is commonly used, as it requires minimal patient training. However, surgeons should consider either clean intermittent self-catheterization or suprapubic catheter drainage, as both of these methods allow for bladder filling and spontaneous voiding attempts. These alternative bladder drainage methods are associated with decreased rates of urinary tract infections, and the patient’s progress can be monitored daily with measurements of both spontaneous voids and postvoid residual volumes. Certain women are at higher risk for postoperative voiding dysfunction, including patients aged 65 years or more, those undergoing other concomitant surgical procedures, and those demonstrating low peak-flow rates on preoperative uroflowmetry.²¹Patients with these risk factors are excellent candidates for suprapubic tube placement at the time of surgery. Assisted bladder drainage may be discontinued once the postvoid residual volumes are less than 20% of the total starting bladder volume (or less than 100 mL). Urodynamic evaluation is recommended if postvoid residual volumes remain high 12 weeks after surgery.²⁰If elevated intravesical pressures (more than 35 cm H₂O) are demonstrated with an inadequate voiding pattern on pressure-flow studies, it may be necessary to perform surgery to reduce tension on the sling.

Urethrolysis

A small number of patients undergoing sling procedures will have voiding dysfunction that is significant, persistent, and refractory to therapy. The American Urological Association panel concluded that the overall risk is below 5%, although estimates range from 1% to 20%.⁵These patients require some form of urethrolysis, or surgical release of the sling. One useful technique involves midline transection of the sling from a vaginal approach, with additional paraurethral and retropubic dissection as needed. The exact location of the sling may not always be evident during dissection. Identifying its location may be facilitated by placing the sling on tension with the use of a cystoscope in the urethra while palpating the sling. The morbidity from this procedure is low, the rates of symptom relief are high, and most investigators have found that the majority of patients remain continent, even without resuspension.²²A variety of other techniques for treating obstructive symptoms after sling procedures have been reported. Brubaker²³describes a technique of releasing the rectus fascia attachments of the sling sutures. Carr and colleagues²⁴describe vaginal, retropubic and infrapubic approaches to urethrolysis, while Petrou²⁵describes a suprameatal, transvaginal approach.

Bone Anchor Complications

Bone anchors were introduced by Leach²⁶in 1988 for pubic bone fixation of sutures during needle suspension procedures. It was felt that such a solid suprapubic fixation would improve the success rate for these procedures by reducing suture pull-through in the periurethral fascia, and decrease the discomfort associated with tying sutures over the rectus fascia. Since that time, a variety of bone anchor designs have been described for both needle suspensions and slings. Recently, a transvaginal sling procedure has been introduced that enables surgeons to attach a suburethral graft to the inferior pubic rami or posterior aspect of the pubis, thereby eliminating the need for a suprapubic incision. The use of bone anchors can be complicated by osteomyelitis, especially when the breach of bone cortex is in close proximity to vaginal flora. Indeed, there are at least six cases and two case reports of pubic osteomyelitis in the literature.^27,28Although the incidence of this complication is quite low, osteomyelitis should be suspected in women who have undergone pubic bone anchor placement if they present with recurrent or persistent suprapubic swelling, pain, drainage, or wound infections that are refractory to conservative treatment. The diagnosis may be confirmed by blood cultures and bone scans (triple-phase, tagged white blood cells, or gallium). Aggressive surgical debridement with removal of the anchors, along with prolonged intravenous antibiotic treatment, is usually required for successful management.

CONCLUSION

As more antiincontinence procedures are performed, clinicians must be aware of their potential complications, including those more commonly seen with sling procedures. Women who have undergone sling placement may present at any point with a variety of symptoms, including irritative voiding, vaginal bleeding, and pelvic pain, which may at first appear unrelated to their surgery. Successful management depends on the clinician approaching these problems with an understanding of the procedures and a high index of suspicion.

Peter L. Rosenblatt, MD, is an assistant professor of obstetrics, gynecology, and reproductive biology at Harvard Medical School, Boston, Mass, director of urogynecology at Beth Israel Deaconess Medical Center, Boston, Mass, and co-director of urogynecology at Mount Auburn Hospital, Cambridge, Mass; Charles R. Rardin, MD, is a clinical instructor of obstetrics, gynecology, and reproductive biology at Harvard Medical School, and a clinical fellow, division of urogynecology at Mount Auburn Hospital; and Neeraj Kohli, MD, is an assistant professor of obstetrics, gynecology, and reproductive biology at Harvard Medical School, and co-director of urogynecology at Mount Auburn Hospital.

REFERENCES

1. Lenderking WR, Nackley JF, Anderson RB, Testa MA. A review of the quality-of-life aspects of urinary urge incontinence. Pharmacoeconomics. 1996;9(1):11-23.
2. Wall LL, Norton PA, DeLancey JOL. Practical Urogynecology. Baltimore, Md: Williams & Wilkins; 1993;.
3. US markets for urological products. Stress urinary incontinence forecasts 1996-2001. Medical Data International Report 1998. Rp 191112., exhibit 5-11:534.
4. Hohenfellner R, Petrie E. Sling procedures. In: Stanton SL, Tanagho E, eds. Surgery of Female Incontinence, ed 2. Berlin, Ger: Springer-Verlag; 1986:105-113.
5. Leach GE, Dmochowski RR, Appell RA, et al. Female stress urinary incontinence clinical guidelines panel summary report on surgical management of female stress urinary incontinence. J Urol. 1997;158:875-880.
6. Agency for Health Care Policy and Research. Urinary incontinence in adults: acute and chronic management. Clinical Practice Guideline, No. 2 (1996 update). AHCPR Publication No. 96-0682: March 1996.
7. Sand PK, Bowen LW, Panganiban R, Ostergard DR. The low pressure urethra as a factor in failed retropubic urethropexy. Obstet Gynecol. 1987;69:399-402.
8. Blaivas JG. Treatment of female incontinence secondary to damage or loss. Urol Clin North Am. 1991;18:355-363.
9. Appell RA. Primary slings for everyone with genuine stress incontinence? The argument for… Int Urogynecol J. 1998;9:249-251.
10. Labasky RF, Soper T. Reduction of patient morbidity and cost using frozen cadaveric fascia lata for the pubovaginal sling [abstract 1794]. J Urol. 1997;157:459A.
11. Chaikin DC, Blaivas JG. Weakened cadaveric fascial sling: an unexpected cause of failure. J Urol. 1998;160:2151.
12. Fitzgerald MP, Mollenhauer J, Bitterman P, Brubaker L. Functional failure of fascia lata allografts. Am J Obstet Gynecol. 1999;18:1339-1346.
13. Weinberger MW, Ostergard DR. Long-term clinical and urodynamics evaluation of the polytetrafluoroethylene suburethral sling for treatment of genuine stress incontinence. Obstet Gynecol. 1995;86:92-96.
14. Young SB, Rosenblatt PL, Pingeton DM, et al. The Mersilene mesh suburethral sling: a clinical and urodynamics evaluation. Am J Obstet Gynecol. 1995;173:1719-1726.
15. Clemens JQ, DeLancey JO, Faerber GJ, et al. Urinary tract erosions after synthetic pubovaginal slings: diagnosis and management strategy. Urology. 2000;56(4):589-594.
16. Handa VL, Stone A. Erosion of a fascial sling into the urethra. Urology. 1999;54(5):923.
17. Myers DL, LaSala CA. Conservative surgical management of Mersilene mesh suburethral sling erosion. Am J Obstet Gynecol. 1998;179:1424-1429.
18. Kobashi KC, Dmochowski R, Mee SL, et al. Erosion of woven polyester pubovaginal sling. J Urol. 1999;162: 2070-2072.
19. Schrepferman CG, Griebling TL, Nygaard IE, Kreder KJ. Resolution of urge symptoms following sling cystourethropexy. J Urol. 2000;164(5):1628-1631.
20. Sarver R, Govier FE. Pubovaginal slings: past, present and future. Intl Urogynecol J. 1997;8:358-368.
21. McLennan MT, Melik CF, Bent AE. Clinical and urodynamics predictors of delayed voiding after fascia lata suburethral sling. Obstet Gynecol. 1998;92(4 Pt 1):608-612.
22. Amundsen CL, Guralnick ML, Webster GD. Variations in strategy for the treatment of urethral obstruction after a pubovaginal sling procedure. J Urol. 2000;164:434-437.
23. Brubaker L. Suburethral sling release. Obstet Gynecol. 1995;86(4 Pt 2):686-688.
24. Carr LK, Webster GD. Voiding dysfunction following incontinence surgery: diagnosis and treatment with retropubic or vaginal urethrolysis. J Urol. 1997;157(3):821-823.
25. Petrou SP, Brown JA, Blaivas JG. Suprameatal transvaginal urethrolysis. J Urol. 1999;161(4):1268-1271.
26. Leach GE. Bone fixation technique for transvaginal needle suspension. Urology. 1988;31(5):388-390.
27. Fitzgerald MP, Gitelis S, Brubaker L. Pubic osteomyelitis and granuloma after bone anchor placement. Intl Urogynecol J Pelvic Floor Dysfunct. 1999;10(5):346-348.
28. Matkov TG, Hejna MJ, Coogan CL. Osteomyelitis as a complication of Vesica percutaneous bladder neck suspension. J Urol. 1998;160:1427.

back to top