Sling surgery has replaced Burch colposuspension as the most common surgery for women with stress urinary incontinence (SUI). While incontinence surgery has become a routine part of urologic care, the management of surgical complications and recurrent incontinence can be quite difficult.
It is important that the urologic surgeon is well informed about the most common complications that are associated with sling surgery, and how to best manage them. In addition, the management of recurrent incontinence following sling surgery should follow a stepwise approach, with appropriate diagnostic studies, conservative treatment if possible, and surgery if necessary. While sling surgery in the patient with urethral hypermobility is often straightforward, reoperation for recurrent incontinence can be more technically challenging.
The most common complication reported with sling surgery is bladder perforation during needle passage. Most large series report an incidence of bladder perforation of between 1–15%, and an average perforation rate of 5%. Bladder perforation is best avoided by emptying the bladder, and by providing finger guidance during needle passage through the retropubic space. Early reports of the transobturator sling document a lower rate of bladder and urethral injury by needle passage, which generally occurs in less than 1% of patients.
Bladder laceration can occur during dissection of the vaginal wall away from the pubocervical fascia or during perforation of the fascia into the retropubic space (which might be necessary for placement of bone-anchors or for lateral cystocele defect repair). Transvaginal repair should be performed, if possible, with a two-layer closure using absorbable sutures. If exposure is suboptimal, a transabdominal repair is indicated. Catheter drainage is recommended for one week.
Injury of the urethra or bladder during vaginal dissection is best avoided by placing a urethral catheter, infiltrating the anterior vaginal wall with normal saline, and using sharp rather than blunt dissection, while staying superficial to the pubocervical fascia. During entry into the retropubic space, cystotomy is best avoided by emptying the bladder, and by staying superficial (lateral) to the perivesical fascia. Tamussino et al., presented a nice review of a reoperation in 2,795 patients undergoing a Tension Free Vaginal Tape operation. (Obstet Gynecol 2001) According to this paper the most frequently reported complication requiring a reoperation was related to bleeding (2.6% of cases) and the cause of bleeding was in the majority of the cases attributable to TVT operation. The second most frequently performed reoperation was loosening/ division or removal of the tape, these were done in approximately 1% of all cases.
Interestinglly bleeding can occur also after trans obturator surgery as reported by Sun et al. in (Obstet Gynecol, 2006) or after a minisling Tension Free vaginal tape Secure with a hammock approach as reported by Masata. (Obstet Gynecol, 2008) Sling-related complications vary with the material composition of the sling. While surgery with prepackaged synthetic slings is associated with a quicker recovery, shorter operating time, shorter hospital stay, and lower rate of urinary retention compared with autologous rectus fascial slings, synthetic slings are associated with vaginal extrusion and urethral erosion rates that are 10 times higher than the rates for organic slings.
Clinical presentation can vary from no symptoms to vaginal bleeding, discharge, discomfort, pain, dispareunia or hi-pareunia.
Urethral erosion is likely to result from placement of the sling deep in the periurethral fascia, too close to the urethral spongy tissue or mucosa, or from excessive tension in the sling causing ischemic necrosis. Intraoperative cystourethroscopy is always indicated to rule out urethral or bladder perforation, whether the sling is placed through a retropubic or a transobturator approach.
Over the past five years, polypropylene has emerged as the most widely used sling material. Cadaveric fascia and porcine xenografts tend to be less durable and are associated with less predictable clinical outcomes than synthetic slings. The low rates of urethral erosion and vaginal extrusion are likely to be caused by the favorable characteristics of the loosely woven polypropylene tape. A loose fiber weave with pores >80 μm in diameter theoretically permits the passage of macrophages and tissue ingrowth, thereby allowing integration of the graft into the surrounding tissues.
Other synthetics, such as PTFE (Gore-Tex®) polyester (Dacron® or Protegen), or silicone (InteMesh®) lead to unacceptably high rates of vaginal extrusion and urethral erosion, typically ranging from 4% to 30%. The common suggested strategy with the vaginal extrusion vary upon the clinical presentation and can go from observation and use of topical estrogens to more aggressive approaches such as excision of the extruded segment, burying of the segment or a complete mesh removal if an infection is present.
When bladder or urethral erosion occurs the tape can be removed endoscopically, with an open approach or combining the two. It is recommended not to place another sling (even autologous) at the same time.
Urinary retention is a well-known complication of incontinence surgery, but the incidence depends on the definition of retention. Catheterisation beyond one week is necessary in only 4–8% of patients following sling surgery. The risk of retention increases with age and parity, as well as with concomitant vaginal surgery.
Additionally, the risk is increased in those with adverse characteristics on urodynamic testing (i.e. low flow and/or low voiding pressures). It is for this reason that preoperative urodynamics may be helpful in counseling patients regarding the risk of adverse outcome following sling surgery. Physical examination is necessary to identify any hypersuspension of the urethra, with or without an obstructing cystocele posteriorly.
Urodynamic investigation has demonstrated that a properly placed suburethral sling does not produce obstruction as long as excessive tension is avoided. Many techniques have been described to avoid over tightening of a suburethral sling, and usually involve placing an instrument between the sling and periurethral fascia during tensioning. In patients with intrinsic sphincter deficiency (ISD), greater sling tension might be required to close the incompetent outlet. No quantitative measure of proper sling tension is universally used, however, and, therefore, an ideal method of sling tensioning has not been agreed on.
Treatment of urinary retention can begin conservatively, with alpha-adrenergic blockers and clean intermittent catheterisation as long as the patient is willing and does not suffer from storage phase bladder symptoms or recurrent urinary tract infections. The majority of patients will, however, require a repeat operation. While urethral dilation and transurethral urethrotomy have been described, a more appropriate treatment for early retention after sling surgery (i.e. retention occurring less than 8 weeks postoperatively) is midline sling incision. If relaxation of the urethral support is not adequate, then unilateral or bilateral incision of the sling as it enters the endopelvic fascia is recommended. Early relief of obstruction can be associated with a lower incidence of permanent voiding dysfunction than if treatment for obstruction is delayed.
In cases of long-standing urinary retention, a formal urethrolysis is indicated, either transabdominally or transvaginally. With transabominal urethrolysis, use of an omental flap interposition between the urethra and pubis should be considered. Use of a labial fat graft should be considered if performing urethrolysis transvaginally, especially in patients with previous failed urethrolysis or failed sling incision. Success rates of urethrolysis for postoperative urinary retention are generally high, with 65–93% of patients voiding well, resolution of urgency incontinence in 67%, and a recurrent SUI rate of less than 10%.
Voiding dysfunction is the most common complication following anti-incontinence surgery. Although the reported incidence varies with the definition of voiding dysfunction used, up to 20% of patients will have new urinary complaints postoperatively, most commonly de novo urgency. Unfortunately, it is difficult to accurately diagnose and distinguish between urethral and bladder dysfunction based on history and physical examination alone.
Behavioral management with restriction of fluid intake and caffeine consumption, timed voiding, and double voiding is often helpful. Pharmacotherapy is often used, with alpha blockers for retentive symptoms and antimuscarinics for irritative symptoms. Persistent voiding dysfunction is an indication for urodynamic investigations.Failure to demonstrate unstable bladder contractions on urodynamic testing does not, however, rule out detrusor overactivity, and there is no standard definition of bladder outlet obstruction. While some investigators suggest that a voiding pressure >20 cm H2O and a peak urinary flow rate <15 ml/s signifies obstruction, in many instances there is no bladder contraction during urodynamic studies.
Bladder outlet obstruction can, therefore, be difficult to diagnose. The video urodynamic testing has proven useful in assessing patients with voiding dysfunction following sling surgery. A narrowing or cut-off of radiocontrast agent at the level of the sling can indicate surgical obstruction.
If there is bladder outlet obstruction, and conservative management fails, then urethrolysis is recommended. With detrusor overactivity in the absence of obstruction, pharmacotherapy is indicated. When conservative management with pharmacotherapy is unsuccessful, sacral neuromodulation is suggested. In cases of failed neuromodulation, augmentation cystoplasty may be indicated.
Proper postoperative management Sling surgery for women with SUI has become a routine urologic procedure. The incontinence surgeon must be aware of potential complications and their proper intraoperative and postoperative management. In patients with recurrent incontinence, evaluation and management should follow a stepwise approach, with appropriate diagnostic studies, conservative treatment if possible, and surgery if necessary. The surgical management of failed sling procedures can be considerably more complicated than the initial operation. In patients with recurrent hypermobility, placement of a new sling is often straightforward and successful. In patients with a fixed and incompetent urethra, however, periurethral bulking agents, pubovaginal slings or spiral slings (with varying degrees of tension) might be indicated. In selected patients, AUS placement can also be part of the treatment algorithm.
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