Retropubic
Transobturator
Single incision
Vaginal wall mesh exposure
1.5% [2]
0.4% [2]
Higher than “inside-to-out” TO slings; RR 3.75, 95% CI 1.42 to 9.86 [5]
Bladder injury
2.7–3.9% [2]
0.4% [2]
0.8% [6]
Urethral injury
0.2–0.3% [2]
0.2–0.3% [2]
<4% [5]
Bowel injury
0–0.04% [2]
0% [2]
0.8% [6]
IUGA/ICS published a consensus on mesh complications terminology in 2011 [4]. The generic term of “erosion” should be avoided, as it implies a wearing away by friction or pressure, and it does not represent the clinical presentations encountered. IUGA/ICS instead suggested use of the term exposure to represent vaginal mesh that is visible or palpable through the separated mucosa at the original vaginal incision site, whereas the term extrusion was suggested to represent the delayed process whereby mesh gradually passes through the vaginal wall. However, these definitions were suggested after many reports were already published in the literature, and the events of mesh exposure vs. extrusion can be difficult to distinguish. Therefore, in this chapter we will use the term mesh exposure to describe mesh that is visible or palpable through the vaginal wall mucosa, whether at the incision site or elsewhere, at any time point. Mesh perforation will describe a delayed event where mesh has entered an adjacent hollow organ, either the urinary tract (urethra or bladder) or the bowel. Trocar injury will refer to the recognized passage of the sling trocar through the vaginal wall, or into the urethra, bladder, or bowel at the time of sling placement.
The astute reader must be careful to distinguish between the two different types of publications reporting on MUS complications. One group of studies and meta-analyses report complications from index surgeries, and a second group of publications reports symptoms identified in patients referred to a regional center for management of complications. The former are felt to represent “real-world” complication rates, whereas the latter are affected by selection bias, because patients referred to these institutions have more complicated sling problems requiring expert management.
Midurethral Sling Surgery Uses Less Vaginal Dissection
All MUS procedures, including retropubic (RP), transobturator (TO), or single-incision slings (SIS ), are “tension free.” They provide support under the hypermobile urethra only during times of increased abdominal pressure, leading to “dynamic kinking” of the urethra which prevents leakage of urine. The transvaginal tape (TVT ) was the first midurethral sling [1], and it requires a less extensive dissection than the traditional fascial pubovaginal sling. The traditional pubovaginal sling dissection requires a wide vaginal incision and subsequent periurethral mobilization to permit passage of the surgeon’s finger (not just a narrow trocar) into the retropubic space. This allows for controlled guidance of the sling passage needle from the suprapubic incision onto the surgeon’s finger as it is passed behind the pubic bone and delivered through the vaginal incision. Precise control of the needle minimizes the chance of inadvertent bladder injury. In contrast, the TVT is a trocar-based device that places a piece of mesh tape retropubically through a limited vaginal incision and exits through a small suprapubic skin incision. The vaginal-to-suprapubic trocar passage is also called the “bottom-up” approach. The TVT procedure introduced “blind” passage of the trocar through the retropubic space, as it is not passed directly on the surgeon’s finger. This blind passage resulted in increased bladder and bowel injury, and by 2001, these complications helped to promote the development of the TO sling. The TO sling follows a lateral vector, the natural curve of the vaginal wall, to pass the sling through the obturator fossa, which allows it to avoid the blind retropubic pass [7]. With subsequent development of the “top-down” retropubic sling in 2001 and then the “inside-out” transobturator sling in 2003, four different methods of placing a MUS were available (RP: “bottom-up” and “top-down”; TO: “inside-out” and “outside-in”), each with its own benefits and complication profiles, secondary to their different vectors of passage. The SIS sling was FDA approved in 2006. It was designed to have the benefits of lateral vector passage, like a TO sling, but to avoid passage through the adductor muscle complex of the thigh, which is associated with rare pain complications.
This chapter will review MUS complications and their management, with a specific emphasis on two main concepts:
- 1.
Mesh exposure, defined as exposed mesh visible or palpable through the full-thickness vaginal wall at either the incision site or a separate site. These may be early or delayed.
- 2.
Mesh perforation, very early presentation may represent a technical error of sling trocar placement through the urethra, bladder, or bowel, and when delayed, it may represent more patient-specific tissue healing factors. While these complications are uncommon overall, a clear understanding of the sling-specific and patient-specific risk factors and the utility of prompt diagnosis and appropriate treatment are critical for the pelvic reconstructive surgeon.
Mesh Exposure
Mesh exposure , defined as exposed mesh visible or palpable through the full-thickness vaginal wall, is rare after midurethral sling, occurring in 0–4.4% of patients [8–15]. Mesh exposure occurs secondary to a combination of patient and technical factors. Patient factors include body habitus, poor tissue ingrowth, and poor wound healing. Technical factors include folding or wrinkling of the sling, sling tension, sling material properties, and iatrogenic vaginal wall injury [13, 16]. While increasing age is not a risk factor for mesh exposure [17], younger age is a risk factor for the need for surgical intervention for vaginal mesh exposure, with women 18–39 years old at the highest risk [18]. Younger women may be more sexually active, experience vaginal spotting, dyspareunia, or partner dyspareunia, which prompts evaluation and secondary surgery [18].
Synthetic slings behave differently than autologous, allograft, and xenograft slings. The polypropylene mesh sling is a permanent foreign body that may expose the patient to long-term complications. Biomechanical properties of the sling material play a crucial role in vaginal mesh exposure. Although various materials have been used for sling surgery, the literature strongly supports the use of the Amid Classification Type I mesh, a macroporous weaved monofilament polypropylene mesh [19]. Type I mesh has a large pore size that allows for tissue ingrowth and incorporation into the surrounding tissue, which minimizes sling encapsulation and infection [20, 21]. Historical use of nontype I mesh products, with their smaller pore size, resulted in poor tissue incorporation into the mesh, more encapsulation, and subsequently higher rates of vaginal mesh infection and exposure. Examples include ObTape® (Mentor Corp, Santa Barbara, CA, USA) and Uratape® (Mentor Corp, Santa Barbara, CA, USA), with reported mesh exposure rates of 19% and 12%, respectively [16, 22].
Mesh Exposure Reflects the RP and TO Vectors of Placement
Vector differences when passing the RP and TO sling trocars are directly related to the different rates and locations of vaginal wall mesh exposure. The increased incidence of mesh exposure with TO slings reflects the “smile” sling vector traveling from the midurethra, coursing laterally along the anterior vaginal wall, and passing toward the obturator foramen. At the lateral vaginal sulcus there is a potential for thinning of the vaginal wall, either due to individual patient anatomy or to surgeon dissection, and this may lead to mesh exposure. The RP sling has a “U” vector, which travels underneath the urethra, then directly behind the pubic bone. It does not travel laterally along the anterior vaginal wall. RP slings have a lower rate of mesh exposure than TO slings because passage of the RP sling avoids the lateral vaginal sulci [23, 24]. Mesh exposure after a RP sling most commonly occurs in the midline at the incision site.
Both RP and TO slings have two different entry points and trajectories: either from the vaginal incision to the outside skin (“bottom-up” RP sling and “inside-out” TO sling) or from the outside skin to the vaginal incision (“top-down” RP sling and “outside-in” TO sling). Because each courses laterally, both TO approaches still carry the risk of vaginal perforation at the lateral vaginal sulcus. In 341 women who underwent TO sling, Abdel-Fattah and colleagues reported an increased risk of vaginal wall mesh exposure with the “outside-in” technique. Only 3 of 20 lateral sulcus injuries occurred after “inside-out” TO slings versus 17 of 20 after “outside-in” TO slings (p = 0.001) [25]. Similar results were noted by But in 2008 [26]. The reason for the increased exposure rate with the “outside-in” approach may be due to the additional dissection required to allow a finger to receive the TO trocar at the pubic bone. It may also be secondary to the relative lack of three-dimensional orientation when receiving the sling trocar entering from the groin crease. This is in contrast with the “inside-out” technique, in which the surgeon places the trocar in a precise and controlled position under direct vision relative to the vaginal wall and urethra.
The single-incision sling—or “mini-sling”—follows the same vector as the TO sling; however, due to its shorter length, it only reaches to the obturator internus membrane. Because it has a similar lateral vector of passage along the anterior vaginal wall as the TO sling, SIS have a rate of mesh exposure of 1.3% (95% CI 0.8–1.9), comparable to the TO sling [27].
In a 2014 meta-analysis, the rate of vaginal wall perforation by TO sling was 2.8% (95% CI 2.2–3.5%), whereas the rate of vaginal wall perforation by the RP sling was 0.73% (95% CI 0.40–1.2%) [27]. The Trial of Midurethral Slings (TOMUS ), a high-quality multicenter RCT of 597 women, reported that the recognized vaginal wall trocar or perforation rate at the time of surgery was 4.4% with TO sling and 2% with RP sling, and the mesh exposure rates on follow-up were 1.3% with TO sling and 0.7% with RP sling [15].
Surgical Tips to Minimize the Risk of Vaginal Wall Mesh Exposure
Optimal vaginal wall thickness during dissection is essential to avoid urethral or vaginal wall thinning and to minimize vaginal wall trocar perforation. Hydrodissection is performed prior to incision with 10 cc of saline at the midurethra, and hydrodissection may be performed laterally to the vaginal sulcus for the TO sling. This hydrodissection creates a submucosal space that can facilitate the creation of the optimal plane. We place the vaginal wall over the midurethra on tension using a toothed forceps to help the 18-gauge injection needle find a surgical plane at an appropriate depth. Early vaginal wall blanching means the injection is too superficial, and lack of an obvious injection bleb means the hydrodissection is too deep. Direct visualization and palpation of the sling trocar trajectory during all phases of passage are critical to inform the surgeon of vaginal wall thickness.
If inadvertent perforation of the lateral vaginal mucosa is noted, a new deeper access for the sling trocar is created using Metzenbaum scissors , and the sling trocar is repassed into the new path with thicker vaginal wall coverage. The vaginal wall perforation should be closed with an absorbable suture. In TOMUS , perforation of the vaginal epithelium managed by operative repair and replacement of the sling led to no short- or long-term complications at 2 years [15].
Another potential risk factor for mesh exposure is postoperative formation of a vaginal wall hematoma. The hematoma may either cause incisional pressure, resulting in reopening of the incision, or it may cause mucosal separation with mesh exposure as the hematoma liquefies and drains. Good mucosal closure may minimize delayed mucosal separation, and if the vaginal dissection has caused more bleeding than normal, some surgeons will try to minimize the vaginal wall hematoma by placing a vaginal pack that is removed in the recovery room after 1–2 h.
See Box 17.1 for key points for prevention and management of vaginal wall perforation.
Box 17.1 Key Points: Prevention and Management of Vaginal Wall Perforation
Prevention
Adequate hydrodissection
Transobturator sling, hydrodissection laterally to sulcus
Confirm vaginal wall thickness by palpation
Management
Identification is key
Remove trocar, create deeper plane, beware of urethra, replace trocar
Close vaginal wall injury with 3–0 Vicryl
Clinical Presentation of Vaginal Wall Mesh Exposure
Vaginal wall mesh exposure may be early or delayed and has a variety of presentations. A patient may be asymptomatic, with the sling visible or palpable only on physical examination. The symptomatic patient may have vaginal spotting or discharge, vaginal pain, dyspareunia, and/or partner dyspareunia. Because symptoms can be nonspecific, one must have a high index of suspicion with any postoperative sling patient.
Symptoms may begin within a few weeks to a few months after the procedure. Osborn and colleagues found that patients who had mesh exposure presented at a median of 6 months from the time of their initial surgery [28]. The most common symptom was vaginal bleeding (20/50 women), reported as intermittent spotting increasing after intercourse. Vaginal discharge was reported in 3/50, 18/50 had dyspareunia, and 20/50 women had vaginal pain. Kokanali reported the most common presenting symptom of vaginal wall mesh exposure was the patient feeling the mesh on self-examination [29]. In the authors’ experience, when patients report vaginal pain or dyspareunia, we are also concerned that the sling may be too tight and are careful to evaluate for evidence of pelvic floor muscle dysfunction/spasm.
According to a 2013 review of 188,454 index patients who underwent midurethral sling placement, the risk of surgical removal or revision due to mesh exposure increases throughout the first 4 years after surgery, from 1.3% at 1 year to 2.1% at 4 years postoperatively. After that time, the rate of surgical intervention for mesh exposure remains around 2.5% [18]. These findings are consistent with the 5-year results from the Trial of Midurethral Slings (TOMUS ), which reported a 1.7% rate of mesh exposure [30].
The RP MUS has been extensively studied, with average follow-up greater than 10 years in several publications. These studies inform the clinician that there is a continued, but small, risk for vaginal mesh exposure. In the Nordic study, only one of 46 women who did not have mesh exposure at 7 years and returned for the 17-year physical examination had mesh exposure [31]. Similarly, Svenningsen reported 0.6% mesh exposure rate at mean follow-up of almost 11 years [32]. The longest published TO sling follow-up study reported 2/61 women had vaginal mesh exposure at 5 years, and, importantly, both were recognized on the 1 year exam [33].
Clinical Evaluation of Mesh Exposure
A thorough pelvic examination is typically adequate to diagnose vaginal mesh exposure. Careful visual inspection of the entire anterior vaginal wall and the lateral sulcus should be methodically performed, making special note of the location of the vaginal wall incision. The urethra should then be methodically palpated, beginning in the midline and extending laterally to each sulcus, feeling for a lateral exposure. Careful examination of the lateral vaginal fornices is particularly important after a TO or SIS . Mesh may not readily be visualized but may only be palpated as a grainy, superficial structure, sometimes with a sharp edge.
Inspection and palpation of the suprapubic and bilateral lower quadrants and each groin crease should also be performed, looking for any evidence of early or delayed wound issues, such as tenderness, inflammatory changes, drainage, or a potential fistula tract. In the patient who is difficult to examine, vaginoscopy with a cystoscope, with manual compression of the labia to permit filling of the vagina, may allow visualization of mesh exposure, though this technique is more commonly used to look for proximal vaginal wall mesh exposure after prolapse surgery.
Management of Vaginal Wall Mesh Exposure
Once exposed vaginal mesh is recognized, there are multiple appropriate treatment strategies based on the patient’s quality of life and expectations. If the patient is asymptomatic, particularly if she is not sexually active, observation may be appropriate. While addition of vaginal estrogen is commonplace, a paucity of literature exists demonstrating the efficacy of estrogen replacement therapy for complete regrowth of the vaginal epithelium over the exposed mesh. In 2009 Higgins and colleagues evaluated the effect of vaginal estrogen in an ovariectomized rabbit vagina model with mesh implantation. Estrogen supplementation did show some beneficial effects, including reversal of vaginal atrophy and increased deposition of collagen into the mesh [34]. In the authors’ experience, vaginal estrogen can make the mucosa more vascular and healthy, as well as reduce the size of the exposure, but very rarely will it result in complete coverage of the mesh exposure.
Type I mesh allows for excellent tissue ingrowth and typically remains uninfected even when exposed. Thus, exposed mesh that is well incorporated can be left intact and re-covered with vaginal epithelium with minimal risk of infection. However, if the mesh has folds, wrinkles, or any ridges, excision and revision may be necessary to reduce the risk of repeat exposure. Some older nontype I mesh slings may be found free floating without any tissue incorporation (Fig. 17.1) and sometimes with obvious infection. These slings need to be excised until healthy tissue is seen investing and surrounding the sling. In the authors’ practice, complete sling removal is not commonly needed unless the sling is clearly not incorporated into the tissue, suggesting possible infection, which is an unusual finding with type I mesh. More extensive mesh removal along the course of the vaginal wall may be considered if the initial attempt at mesh trimming and vaginal mucosal flap coverage has failed. However, extensive retropubic, obturator, or groin dissection to remove all portions of the sling is typically unnecessary. In the case reports of these extensive procedures, very specific indications were present .
Fig. 17.1
Midurethral sling mesh exposure through vaginal wall. Note this nontype I mesh is not well incorporated and is free floating with calcifications. The mesh will need to be resected back to where it is well incorporated into the tissue
If a patient is symptomatic from her mesh exposure, operative intervention is reasonable. Location of the procedure—whether in the office or in the operating room—is dependent on surgeon experience, the patient’s tolerance, and the size and location of the exposure. Myers and coworkers successfully managed small exposures less than 5 mm via an office-based excision, while exposures 6 mm to 1 cm were managed in the operating room [35]. Small midline exposures may be managed in the office by experienced surgeons. Local anesthetic is infiltrated around the exposure, and an incision is made from the mesh exposure into the surrounding healthy tissue. If significant inflammatory or granulation tissue is present, an elliptical excision of the granulated vaginal mucosal edge may be needed to expose healthy tissue that can then be mobilized. Once the extent of the exposure is clarified, and healthy vaginal wall exposed, dissection superficial to the mesh but under the vaginal mucosa helps to create mobile vaginal wall flaps to provide tension-free coverage of the exposed mesh. The Finnish nationwide review reported that 10/1455 MUS procedures had mesh exposure [9]. Three of these patients were managed without surgical intervention, four patients had the mesh re-covered with mobilized vaginal mucosa, and two patients required partial mesh excision. In this cohort, continence was maintained in all patients, regardless of the management.
Mesh excision can improve sexual function. In Kuhn and coworkers, the sexual function in women with MUS mesh exposure was evaluated pre- and postoperatively with the Female Sexual Function Index [FSFI ] [36]. Of 21 exposures, 18 had mesh re-coverage with vaginal mucosa. Two patients had recurrent exposure, one had repeat vaginal closure, and the other had partial sling excision and vaginal closure. Importantly, FSFI domains of desire, arousal, lubrication, satisfaction, and pain improved significantly.
The authors recommend leaving well-incorporated exposed mesh in situ and covering it with vaginal epithelium. An absorbable suture, such as a 3–0 VICRYL® (Ethicon, Somerville, NJ, USA), is used to close the mobilized vaginal wall in a tension-free manner. The patient should abstain from intercourse or tampon use for several weeks to permit healing. If the patient has a large exposure (>1 cm), exposure at the lateral vaginal sulcus, or if surgeon comfort dictates, we prefer surgical management in the operating room with better retraction and exposure. Removal of a portion of the sling can be performed if indicated. The patient should be counseled on the risks and benefits of removing or covering only the exposed mesh versus excision of a larger section of the sling . It is important to recognize that removal of a large section of the sling does risk injury to the urethra and recurrence of stress incontinence. If a large section of a RP sling is to be removed, the sling can be incised and dissected lateral to the urethra behind the pubic bone. Chasing the RP sling into the retropubic space is done only with bladder or other adjacent organ injury that demands a more aggressive approach. Because it requires extensive dissection behind the pubic bone, which is difficult to perform vaginally, complete removal of a RP sling from the retropubic space usually requires a concurrent open or laparoscopic/robotic approach. Similarly, the TO sling can be traced laterally behind the pubic bone to its path through the obturator internus muscle. Removing the TO sling from the obturator fossa or groin crease/adductor muscles should only be done in the rare patient who has significant symptoms such as pelvic floor muscle or adductor muscle pain. Dissection past the obturator internus from the vaginal approach can be difficult and may be associated with bleeding that is difficult to control. Therefore, if complete removal is indicated, a groin crease or medial thigh counter incision may be needed. SIS sling removal is similar to the vaginal approach of TO sling removal.
See Box 17.2 for key points for management of vaginal mesh exposure.
Box 17.2 Key Points: Management of Vaginal Mesh Exposure
Asymptomatic and not sexually active: consider observation
Symptomatic
Exam
Confirm location
Identify all exposed mesh
Surgical intervention
Resection
Remove inflamed mucosa surrounding exposed mesh
Remove wrinkled, folded, or prominent mesh
Remove “free-floating” poorly incorporated mesh
Closure
Mobilize vaginal wall to allow tension-free closure
Close with 3–0 SAS
Mesh Perforation: Adjacent Organs
Bladder
Bladder Injury Is Higher with the RP Sling
Bladder perforation is more common with RP slings due to the blind pass and trajectory of the retropubic trocar behind the pubic bone. Most current literature describes bladder trocar injury at the time of the index surgery. A 2015 meta-analysis reported a 3.2% rate of bladder perforation with RP sling, significantly higher than the TO sling rate of 0.2% (OR 5.72, CI 2.94–11.12, p < 0.0001) [37]. The TOMUS trial, which consisted of high volume fellowship-trained surgeons practicing at teaching institutions, reported a 5% rate of bladder perforation and 1% urethral perforation rate with the RP sling compared to 0% bladder and 0% urethral perforation with the TO sling [15]. The rate of bladder or urethral trocar injury with TO surgery in other randomized studies is reported between 0 and 1.3% [15, 38]. Interestingly, Tamussino reported 9/10 bladder injuries occurred with the “outside-in” TO trocar technique [39].
Several risk factors are associated with bladder perforation. First, as with any procedure, there is a learning curve, so proper training and surgeon experience are important. Stav and coworkers reported that 32/34 (94%) bladder perforations were by surgeons who had performed fewer than 50 slings (p < 0.0001). All but one of these perforations was by a RP sling, and the route of trocar insertion (“top-down” or “bottom-up”) did not affect risk [40]. History of prior abdominal or pelvic surgery that may scar the retropubic space can increase the risk of bladder perforation, including colposuspension, cesarean section, or prior anti-incontinence surgery. Diabetes mellitus is a medical comorbidity that may increase the risk of bladder perforation. Chen noted an increased risk of mesh perforation into the bladder in diabetic patients, possibly related to their poor wound healing abilities [41]. Interestingly several series have reported decreased rates of bladder perforations with RP slings in patients with BMI > 30 kg/m2 [40, 42, 43]. The protective mechanism may be that the retropubic fat pushes the bladder away from the pubic bone, shielding the bladder from the trocar .
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