Complications of Female Incontinence and Pelvic Reconstructive Surgery (Current Clinical Urology) 2nd ed.

11. Complications of Biologic and Synthetic Slings and Their Management

Laura Chang-Kit Melissa Kaufman1 and Roger R. Dmochowski1

(1)

Department of Urological Surgery, Vanderbilt University School of Medicine, A1302 Medical Center North, Nashville, TN 37232, USA

Laura Chang-Kit

Email: laurachangkit@yahoo.com

Abstract

Female stress urinary incontinence (SUI) is estimated to affect 49% of community dwelling women [1], although true prevalence is unknown. Patient underreporting due to social embarrassment or fear as well as differences in the definition of SUI between studies contribute to the probable substantial underestimation of SUI patients [2, 3]. The financial impact of SUI is exceptional with one report estimating the healthcare burden of SUI at over US $16 billion dollars per year [4].

Introduction

Female stress urinary incontinence (SUI) is estimated to affect 49% of community dwelling women [1], although true prevalence is unknown. Patient underreporting due to social embarrassment or fear as well as differences in the definition of SUI between studies contribute to the probable substantial underestimation of SUI patients [23]. The financial impact of SUI is exceptional with one report estimating the healthcare burden of SUI at over US $16 billion dollars per year [4].

Slings are currently the most popular procedure for the surgical correction of female SUI. Sling surgery involves placement of graft material at the level of the bladder neck and proximal third of urethra (pubovaginal sling [PVS]) or midurethra (midurethral sling [MUS]). Numerous techniques and graft materials (autologous fascia, allograft, xenograft, and synthetic) have been developed over several decades for sling placement.

This chapter will focus on the diagnosis, evaluation, and management of complications specific to sling placement. Nonurologic perioperative considerations and complications (for example anticoagulation and risks of anesthesia) are discussed elsewhere in this book and will not be addressed in this chapter.

Use of Slings for Stress Urinary Incontinence

According to Medicare data, by 2001, PVS was the leading anti-incontinence procedure for SUI performed in the USA, surpassing more traditional retropubic needle suspensions and anterior urethropexies [5]. In the last decade however, midurethral polypropylene slings have emerged as the most commonly performed sling procedure across the USA and Europe. MUS sling use has expanded secondary to the short operative time, minimal morbidity, rapid convalescence, technical ease, and reproducibility of the procedures, as well as their long-term efficacy and durability [6].

Undoubtedly, the most commonly used and evaluated material for PVS is autologous fascia, which has shown excellent efficacy and longevity [7]. Cadaveric fascia has been used with more limited efficacy and durability and thus its use has dramatically declined [8]. Xenografts such as porcine dermis, porcine small intestinal submucosa, and bovine pericardium have also been used, with the most studied xenograft being porcine dermis. Synthetic bladder neck slings have fallen out of favor due to the tendency to extrude through the vagina or perforate into the lower urinary tract [9]. Therefore, this chapter will focus on the autologous fascia PVS procedure and its complications as representative of the generalized experience with biologic slings.

MUS can be placed through a transvaginal, suprapubic, or transobturator approach. In general, these slings are composed of type I synthetic polypropylene monofilamentous mesh, with a pore size between 75 and 150 μm. This pore size is critical to allow fibrous tissue in-growth as well as leukocyte and macrophage entry in order to reduce bacterial colonization. Single-incision slings (aka “mini-slings”) are the newest generation of MUS, which require only one vaginal incision without any entry or exit incisions. Unlike their predecessors, the mini-slings are meant to be entirely placed and stay within the pelvis, without any incorporation of the anterior abdominal wall or inner thigh musculature. As the data on these mini-slings is still limited, these will not be discussed in this chapter.

Mechanism of Action

The understanding of how slings correct SUI continues to evolve. In general, the aim of any SUI surgery is to augment the urethral closure pressures to prevent involuntary urinary leakage when there are increases in abdominal pressures [10]. PVSs are placed without any added tension and are thought to work by a combination of mechanisms: (1) to create a suburethral supporting hammock at the bladder neck and proximal urethra, which acts as a backboard against which the urethra is compressed during periods of increased intra-abdominal pressures (imitating the “hammock theory of continence”) and (2) to stabilize the bladder neck and proximal urethra in an “intra-abdominal” position (reducing hypermobility) such that pressure transmission is maximized [11]. In addition, autologous fascia PVS can be purposely tensioned to compress and/or obstruct the urethra in cases of severe intrinsic sphincter deficiency (ISD) such as in decentralizing neuropathic conditions.

MUSs are also placed in a “tension-free” fashion and are thought to stabilize the midurethral complex, where the urethral closure pressure is maximal [12]. If the posterior wall of the urethra is not well supported, “shear forces” during periods of intra-abdominal pressure can cause the anterior wall of the urethra (attached to the pubic bone by pubourethral ligaments and endopelvic fascia) to move independently of the posterior wall, allowing urine leakage [13]. Another mechanism proposes that the MUS obstructs the downward movement of the urethra, in effect, kinking the urethra during stress maneuvers [14].

Indications and Contraindications

A 2006 prospective study by Petri et al. examined the reasons for 328 complications requiring surgical reintervention after tension-free slings in four European urogynecology centers [15]. Incorrect indication for the initial procedure was determined to be the second most common cause of complications (38%), after poor surgical technique (45%). It is therefore important to review the indications and contraindications for sling placement.

The PVS is considered the gold standard for management of all forms of SUI and is effective in patients with and without hypermobility [16]. It is favored in patients with loss of proximal urethral closure from neuropathic conditions, prior surgery or radiation, and in those with recurrent incontinence after prior failed anti-incontinence surgery [17]. It is also useful in cases of tissue loss such as in urethrovaginal fistulas or after urethral diverticulectomy. The MUS has replaced the PVS as the primary procedure for uncomplicated female SUI. The MUS has also been used effectively in recurrent SUI as well as with concomitant cystocele [7].

Patients with untreated low compliance bladders or urge urinary incontinence without stress incontinence are unsuitable candidates for ANY sling procedure. Interestingly, patients with mixed incontinence who demonstrate both detrusor overactivity and SUI on urodynamic studies often have resolution of their overactive bladder symptoms with satisfactory resolution of their SUI [1819].

According to the 2009 American Urological Association (AUA) Female Stress Urinary Incontinence Guideline Update Panel, synthetic sling surgery for SUI is contraindicated with a concurrent urethrovaginal fistula, urethral erosion, intraoperative urethral injury, and/or urethral diverticulum. These patients are considered higher risk for subsequent urethral erosion, vaginal extrusion, urethrovaginal fistula, and foreign body granuloma formation. Autologous fascia and alternative biologic slings are preferred in these patients for the treatment of concomitant SUI [20].

Patient comorbidities must also be considered when choosing the type of sling to employ. In patients at high risk for abdominal wound complications (e.g., morbidly obese, history of steroid use, previous abdominal wall reconstruction), it is our practice to avoid harvesting rectus fascia for PVS in favor of either fascia lata, or porcine dermis. We also tend towards biologic rather than synthetic slings in patients with estrogen deficiency, previous surgery, or history of pelvic radiation, as well as in very young patients (<30 years old), because of the suspected increased risk of late complications such as erosion into the lower urinary tract. For young women who desire future vaginal deliveries, sling placement in general is a controversial topic and it is our practice to certainly avoid placement of synthetic slings in this population.

Incidence of Sling Complications

One estimate of the overall complication rate of patients undergoing SUI surgery from 1988 to 2000 using a US national database was 13%, with PVS having the lowest complication rate [21]. The overall incidence of complications is difficult to determine and current reported statistics likely underestimate the true incidence. Discrepancies in the accepted definition of “complication” as well as lack of long-term follow-up make tracking complications virtually impossible, compounded by the highly variable reporting of complications [15]. In addition, there are no requirements for mandatory reporting of complications in the US, and there exists no mandatory central database for any procedure. Surgical complications related to medical devices can be voluntarily reported to the US Food and Drug Administration (FDA) Manufacturer and User Facility Device Experience (MAUDE) database; however this is unquestionably underutilized for a myriad of reasons.

In October 2008, the FDA issued a public notification about surgical mesh used in transvaginal SUI and pelvic organ prolapse (POP) surgeries [22]. This was prompted by a 3-year collection of over 1,000 reports of complications related to surgical mesh, with the most frequent being erosion through vaginal epithelium, infection, pain, urinary problems, and recurrence of prolapse and/or incontinence. Perforations into bowel, bladder, and blood vessels during insertion were also reported. In the three years following the 2008 public health notification, another 2,874 mesh-related reports were collected. Based on these findings and after review of the current literature, the FDA issued a safety communication about transvaginal mesh placement for POP in July 2011. Although 1,371 of these reports were associated with SUI repairs, the FDA Obstetrics and Gynecology Devices Panel comprehensively reviewed the use of surgical mesh for SUI procedures in September 2011. The Panel determined that first generation retropubic and transobturator MUSs were safe and effective but that second generation single-incision slings required further clinical studies as current evidence is limited. For now, the FDA continues to evaluate the safety and effectiveness of surgical mesh devices used in any pelvic floor surgery.

Classification of Complications

The first standardized classification and terminology system for complications arising from the insertion of synthetic and biological materials in female pelvic floor surgery was recently reported by the International Continence Society (ICS)/International Urogynecological Association (IUGA) (Table 11.1 and Fig. 11.1) [23]. Each complication is classified according to three aspects: category, time, and site. The aim of the classification is to improve communication amongst providers and allow standardization of research registries. Suggested changes to current terminology include avoidance of the term “erosion,” in favor of the terms “extrusion” or “perforation” when referring to mesh exposures in the vagina or lower urinary tract. Interobserver and intraobserver reliability of the classification is yet to be tested, and widespread adoption is not yet accomplished. As all currently published references use the older nomenclature, this chapter will reflect this to avoid any potential discord in data.

Table 11.1

Recommended terminology in the joint International Continence Society/International Urogynecological Association classification of complications related to insertion of surgical prostheses and grafts in female pelvic floor surgery (adapted from ref. [23])

Terms used

Definition

Prosthesis

A fabricated substitute to assist a damaged body part or to augment or stabilize a hypoplastic structure

A: Mesh

A (prosthetic) network fabric or structure

B: Implant

A surgically inserted or embedded prosthesis

C: Tape (sling)

A flat strip of synthetic material

Graft

Any tissue or organ for transplantation. This term will refer to biological materials inserted

A. Autologous grafts

From the woman’s own tissues, e.g., dura matter, rectus sheath, or fascia lata

B. Allografts

From postmortem tissue banks

C. Xenografts

From other species, e.g., modified porcine dermis, porcine small intestine, bovine pericardium

Complication

A morbid process or event that occurs during the course of a surgery that is not an essential part of that surgery

Contraction

Shrinkage or reduction in size

Prominence

Parts that protrude beyond the surface (e.g., due to wrinkling or folding with no epithelial separation)

Separation

Physically disconnected (e.g., vaginal epithelium)

Exposure

A condition of displaying, revealing, exhibiting or making accessible, e.g., vaginal mesh visualized through separated vaginal epithelium

Extrusion

Passage gradually out of a body structure or tissue

Compromise

Bring into danger

Perforation

Abnormal opening into a hollow organ or viscus

Dehiscence

A bursting open or gaping along natural or sutured line

A213469_1_En_11_Fig1_HTML.gif

Fig. 11.1

A classification of complications related directly to the insertion of prostheses (meshes, implants, and tapes) or grafts in female pelvic floor surgery (figure adapted from ref. [23])

Intraoperative Complications

Autologous Fascia Harvest Site

Autologous fascia is harvested from either the rectus fascia (through a Pfannenstiel incision) or fascia lata. The Pfannenstiel incision has a low incisional hernia rate of 0–2% [24]; however, incisions extending lateral to the edge of the rectus sheath may predispose to hernias and nerve entrapment [25]. It is important to adequately mobilize the abdominal fascia from the underlying rectus and overlying subcutaneous tissue in order to perform a tension-free fascial closure. If a tension-free closure is not possible, our patients have been successfully primarily closed using biological grafts or synthetic mesh with the assistance of general surgery. In obese patients, or patients with expected severe abdominal fascial scarring, fascia lata harvest can be a good option, with minimal morbidity [2627]. Pain on walking, limping, and wound pain can occur, but these symptoms usually last less than 1 week [2728]. Use of a fascial stripper can reduce morbidity [29]. To avoid seroma development, placement of a subcutaneous drain should be considered if a large suprafascial space was created during mobilization of the fascia. If employed, we usually remove this drain the morning following surgery. In order to reduce the risk of wound complications (as well as sling failure), patients are instructed to avoid lifting objects more than 5 lb in weight for 6 weeks and to avoid smoking. They should also aim to control conditions which increase intra-abdominal pressure (e.g., asthma or chronic allergies).

Hemorrhage

Significant bleeding during procedures for SUI is infrequent and transfusion rates range from 1 to 4% [20]. Major vascular injuries to iliac, femoral, obturator, and epigastric vessels during sling surgery have been reported in the literature and the FDA MAUDE database [3031]. Pelvic vessels coursing through the retropubic space, along the pelvic sidewall, and within the vascular pedicle of the bladder can also be injured during dissection or passage of trocars. Solid knowledge of the relative pelvic anatomy and adherence to good surgical technique are paramount in avoiding perioperative hemorrhage.

Preoperative correction of any bleeding diatheses is important prior to any pelvic surgery. The American College of Chest Physicians Patients publishes evidence-based guidelines on the perioperative management of patients who are chronically anticoagulated [32]. Perioperative consultation with the medical service regularly managing the anticoagulation can help balance the risk of hemorrhage with the risk of a thrombotic event.

During vaginal dissection, the source of bleeding can be difficult to identify and control due to lack of direct visualization. During dissection of the vaginal flap from the underlying pubocervical fascia, it is uncommon to encounter significant bleeding if the dissection planes are correct. Initial hydrodissection of the vaginal flap with either injectable saline or lidocaine with epinephrine generally helps to better elucidate this plane. This dissection is more difficult in patients with prior vaginal surgery or radiation who may have severe scarring and thinning of their vaginal wall. Bleeding at this stage signifies an excessively deep incision through the pubocervical fascia into the detrusor or urethra. If this occurs, the dissection should continue in the proper surgical plane and small areas of bleeding can be gently controlled with bipolar cautery.

Blind entry into the retropubic space through the endopelvic fascia either transvaginally with scissors or suprapubically with needles or trocars can lead to considerable bleeding. Perforating scissors should be directed towards the ipsilateral shoulder, with the tips curved away from the bladder. As with curved trocars, if directed too laterally, vessels located on the lateral side of the pelvis can be injured [33]. It is not unusual for some venous bleeding to occur on initial perforation of the endopelvic fascia, and this generally settles spontaneously. Significant retropubic bleeding can usually be quelled by quickly placing the sling and closing the vaginal mucosa. Further tamponade is gained with vaginal packing. Very rarely is the exact source of bleeding identified transvaginally due to poor exposure and visualization; however, this is usually unnecessary to control bleeding. In addition to vaginal compression, placement of a urethral foley catheter with an overinflated balloon on traction at the bladder neck has been described to help tamponade bleeding [34].

Bleeding that is unresponsive to these maneuvers implies major vessel injury and warrants open exploration of the retropubic space or embolization. Initial management includes communicating with anesthesia about the situation, ensuring adequate availability of blood products, and excellent exposure and lighting. Possible intraoperative consultation with a vascular surgeon should be considered. Pelvic bleeding is especially problematic to control because of the confined working space, depth of field, potential for rapid, massive bleeding, and close proximity and high anatomic variation of important structures. Abdominal access to the retropubic space is obtained via a low midline incision, while maintaining vaginal pressure using vaginal packing and manual compression of the anterior vaginal wall up against the pubic symphysis. The retropubic hematoma may be significant, and after initial evacuation of the hematoma, pelvic packing and compression may be required to allow subsequent localization of the bleeding. Vascular control can be accomplished by repairing larger vessels with 4-0 or 5-0 permanant sutures such as Prolene, whereas en bloc ligation is performed with absorbable 3-0 Vicryl sutures. Hemostatic agents such as gelfoam or surgical can be applied over slowly oozing areas if no definite bleeding vessels are identified. If bleeding still cannot be controlled, the pelvis can be packed and the patient brought back for a second laparotomy 48 h later, after resuscitation.

Arterial embolization in pelvic fractures is effective in controlling retroperitoneal hemorrhage with an efficacy rate of 81–100% and low complication rate [3536]. It has also been successfully used in controlling venous bleeding after pelvic surgery following failed open attempts where bleeding could not be localized [37]. This option is particularly valuable if the patient is anticipated to have extensive abdominal or pelvic scarring from previous surgeries or radiation. The patient should be adequately stabilized for transfer to the interventional radiology suite prior to leaving the operating room.

Urinary Tract Injury

During any procedure for SUI, the urinary tract is at high risk for direct injury. Several studies estimate the rate of urinary tract injury during retropubic MUS procedures on patients without a prior history of surgical treatment to be about 7% [3840]. However, in patients with a prior pelvic surgical history, urinary tract injury rates can remarkably approach 37–70% [3839]. Although urinary tract injury with transobturator MUS is reported to be <0.5% [41], suspicion must remain high. Immediate intraoperative detection and management of these injuries can mitigate a myriad of possible debilitating complications such as vesicovaginal fistula or urethral erosion.

Detection of Urinary Tract Injury

Performance of intraoperative cystourethroscopy in all patients undergoing sling surgery in order to detect intraoperative urinary tract injuries is considered standard of practice according to the 2009 AUA guidelines [20]. A rigid or flexible cystoscope should be used to inspect the bladder and urethra prior to the conclusion of the procedure. Optimal visualization of the female urethra is accomplished by using a short beak rigid cystoscope or flexible fiberoptic cystoscope. If a rigid cystoscope is used, a 70° lens provides the best surveillance of the bladder, bladder neck, and ureteral orifices. The bladder must be examined while full, with special attention being paid to the bladder base between the 2 and 10 o’clock positions, where most injuries occur.

Ureteral patency can be assessed by visualizing efflux of previously administered IV indigo carmine or methylene blue from the ureteral orifices. An obvious yet occasionally overlooked confounder at this stage is the history of a unilaterally absent or poorly functioning renal unit. If ureteral patency is in question, a retrograde pyelogram can be conducted.

Bladder and Urethral Injury

Injury to the bladder and urethra typically occurs during vaginal dissection or during trocar passage (Fig. 11.2). Careful adherence to the planes of dissection cannot be overemphasized, especially in patients with vaginal scarring from previous surgery. Perforation of the endopelvic fascia should be carried out only after the bladder has been fully drained, with a urethral foley catheter or metal sound directing the urethra away from the perforating scissors, and with the tips of the scissors directed towards the ipsilateral shoulder, curving away from the bladder. In general, perforating instruments should be kept in close proximity to the respective bony landmarks in order to avoid entry into the bladder or abdominal cavity.

A213469_1_En_11_Fig2_HTML.jpg

Fig. 11.2

Cystoscopic view of Stamey needle perforating anterior bladder wall during autologous fascia pubovaginal sling procedure

Bladder or urethral injury during vaginal dissection or perforation of the endopelvic fascia with scissors can be repaired with a watertight closure using two layers of absorbable suture, followed by catheter drainage for 5–7 days. This injury does not necessarily preclude placement of the autologous fascial sling at the same sitting, depending on patient comorbidities such as prior radiation and size of injury. In these cases, postponement of the PVS and/or possible tissue interposition graft such as a Martius flap can be considered. Placement of a synthetic MUS at the time of an intraoperative urethral injury is contraindicated, due to the higher risk of urethral erosion [20].

A 2009 Cochrane review of MUS examined 18 trials which compared the retropubic vs. transobturator approaches. There was a significantly higher rate of bladder perforation in the retropubic approaches 5.5% vs. 0.3% in the transobturator approaches (relative risk 0.14, 95% confidence interval 0.07–0.26) [30]. Several studies have also identified surgical inexperience as an independent risk factor for bladder perforation during MUS surgery [4243]. If the bladder is perforated during needle placement either during a MUS or PVS procedure, the needle is removed and repassed in the correct trajectory. These injuries do not require primary closure, but catheter drainage for 48–72 h is well advised to allow adequate healing.

Ureteral Injury

Ureteral injury during transvaginal SUI procedures are rare and are usually reported in conjunction with concomitant prolapse repairs. During transvaginal operations, the distal third of the ureter is at highest risk. If ureteral injury is suspected after cystoscopy, intraoperative retrograde pyelogram should be conducted to better assess ureteral integrity. Delayed ureteral injuries can present with flank pain, fever, and wound leakage. Appropriate imaging includes CT urography or retrograde pyelogram. The advantage to retrograde pyelography is that ureteral stenting, if necessary, can be conducted at the same time. Occasionally, the presence of a retroperitoneal urinoma will require percutaneous drainage.

If the ureter is obstructed or kinked, removal of the offending device (suture or needle) should follow and an indwelling ureteral double J stent placed. Partial transection or perforation of the ureter can also be managed with a temporary indwelling stent. Complete transection of the ureter requires formal ureteroneocystotomy.

Bowel Injury

Bowel injury during urinary incontinence procedures has been reported [4044] and usually occurs in patients with previous abdominal surgery [4547]. Bowel injury can occur during entry into the retropubic space during PVS or during trocar passage during MUS. The highest reported risk of bowel complications (1%) is actually with retropubic MUS procedures [20]. Even without history of prior abdominal surgery, awake patients undergoing retropubic MUS procedures can be at risk of bowel perforation if a Valsalva maneuver is undertaken during trocar passage [48]. Placement of the patient in Trendelenberg position prior to trocar passage may reflect the bowel contents cranially and help prevent direct injury. In patients with suspected dense intra-abdominal scarring, preoperative assessment with imaging may assist with operative planning. Sling options which do not involve the retropubic space should strongly be considered.

Injuries diagnosed intraoperatively can be closed primarily if there is no significant contamination of the peritoneal cavity, without the need for bowel diversion. Delayed diagnosis is not uncommon however, and complications such as abscess, sepsis, and even death can result [49]. Interestingly, initial symptoms and signs can be nonspecific, consisting of mild leukocytosis, low-grade fever, general malaise, ileus, and abdominal pain [48]. This can progress to emesis, severe suprapubic or abdominal pain and leakage of bile, or fecal material from wound sites. Early CT imaging and general surgery consultation is recommended. Almost all of these patients will require laparotomy, repair of the bowel injury, and possible bowel resection and/or bowel diversion.

Postoperative Complications

Voiding Dysfunction

The true incidence of voiding dysfunction and iatrogenic bladder outlet obstruction (BOO) after sling surgery is unknown owing to underdiagnosis, misdiagnosis, lack of standard definitions, and underreporting. A literature review from 1966 to 2001 by Dunn et al. reported rates of voiding dysfunction of 4–10% following PVS, and 2–4% following transvaginal tape (TVT) procedures [50]. A recent Cochrane review involving 14 trials of MUS showed postoperative voiding dysfunction occurred significantly less frequently with the transobturator route than with the retropubic route (4% vs. 7%) [30]. In most patients, postoperative voiding dysfunction is transient and resolves with conservative treatments such as catheter drainage or short-term pharmacological therapy. Surgery may be required for patients with severe or prolonged voiding dysfunction refractory to these conservative treatments.

Evaluation of Voiding Dysfunction

Patients with persistent voiding dysfunction after sling surgery must be evaluated with a focused history, physical examination, urinalysis and culture, and cystoscopy. A postvoid residual volume should be documented. We also utilize the AUA Symptom Index in order to compare preoperative and postoperative symptoms and bother. Important factors in the history include preoperative and postoperative storage and voiding symptoms, the temporal relationship of the surgery to the symptoms, and type of sling surgery. Preoperative urodynamic data or flow studies become particularly useful when evaluating postoperative voiding complaints. Physical examination should evaluate for signs of a hyperelevated, fixed bladder neck or urethra, urethral hypermobility, stress incontinence, new or worsened ­pelvic organ prolapse, and vaginal erosion of mesh. Urine studies are critical to rule out urinary tract infection (UTI). Cystoscopy is essential to evaluate for stones, eroded sling, or suture material and other urinary tract injury or pathology including a hypersuspended bladder neck or midurethra, fibrosis, diverticula, or fistula.

Urodynamic evaluation provides useful information about sensation, bladder capacity, compliance, stress incontinence, detrusor overactivity, and coordination of sphincter activity. However, the role of urodynamic studies to evaluate for female BOO is controversial. The diagnosis of female BOO is problematic for a number of reasons. First, there is no accepted “gold standard” nomogram for female BOO, although several nomograms exist. Secondly, some female patients void primarily by pelvic floor relaxation, with barely any rise in their intravesical pressures and with possible Valsalva maneuvers. These patients can be obstructed by a very slight increase in urethral closure pressures. These women may not generate a significant contraction on urodynamic studies, but are still obstructed. Thirdly, although the classic urodynamic “high pressure-low flow” pattern indicative of BOO in men confirms the diagnosis of BOO in women, if present, its absence does not rule out obstruction. To date, there are no consistent preoperative parameters or urodynamic findings which predict success or failure of urethrolysis for BOO [51]. Indeed, patients who have failed to generate a detrusor contraction and those with nondiagnostic urodynamic studies have had the same outcome after urethrolysis as those patients who demonstrated the classic “high pressure-low flow” pattern [52].

How then should the diagnosis of female BOO after sling surgery be made? The diagnosis is obvious in patients with absolute prolonged urinary retention, or who produce the classic urodynamic pattern of obstruction. However, without these, in patients who had normal preoperative voiding function, a culmination of the history, physical exam, temporal relationship of the surgery to the symptoms, and supporting cystoscopic findings should raise the suspicion of BOO.

Urinary Retention and Obstruction

Presentation

Iatrogenic obstruction secondary to sling surgery is the most common cause of female BOO [53], which presents with storage symptoms such as frequency, urgency, and urge incontinence along with obstructive voiding symptoms and elevated PVR. Interestingly, in a study of 51 women undergoing urethrolysis, 75% presented with storage (irritative) symptoms, 61% with voiding (obstructive) symptoms, 55% with de novo urge incontinence, and 24% with persistent retention [54]. Therefore, patients complaining of de novo postoperative storage symptoms, even in the absence of voiding symptoms, should be evaluated for possible obstruction.

Transient Retention

Temporary urethral obstruction can be caused by postoperative edema of the bladder neck or urethra. Retention after nonradical pelvic surgery may also be attributed to a lack of urethral relaxation due to increased sympathetic response to pain, local irritation, anxiety, and trauma [55]. Other possible causes for postoperative retention include use of narcotic or anticholinergic medications, constipation, immobility, and retropubic hematomas. A successful strategy which settles most cases of postoperative retention is to address all the reversible risk factors, while instituting short-term (typically a few days) urethral catheter drainage or clean intermittent catheterization (CIC). Patients should be counseled preoperatively about the potential need for catheterization postoperatively. In complex cases of urethral reconstruction where a PVS is employed, placement of both a urethral and suprapubic catheter may be useful.

Prolonged Retention and Obstruction

The incidence of postoperative retention lasting more than a month or requiring intervention has been reported in 8% of patients following PVS surgery without concomitant prolapse repair, and 3% of women after synthetic MUS placement [20]. Several studies have sought to identify definite risk factors for postoperative obstruction; however, conclusions from these studies are limited by small sample size. Women who void with no or minimal detrusor pressure and who undergo PVS or MUS may be at increased risk of postoperative retention [5657], although other studies have not found this same association [58].

Once the diagnosis of obstruction is established or suspected, surgical options for management of prolonged obstruction include incision of the sling, transvaginal urethrolysis, retropubic urethrolysis, suprameatal transvaginal urethrolysis, and interposition grafts. Urethral dilation and attempts to loosen an obstructing PVS with traction on the dilator in the very early postoperative period can be successful. However, multiple attempts are not advised due to the potential for urethral scarring. Urethral dilation after TVT has been successfully used [59]. We do not advocate use of dilation techniques for synthetic mesh MUS because of the risk of urethral erosion.

Timing of Surgical Intervention

The timing of surgical intervention is debated in the literature and is dependent on the type of procedure, symptom severity, patient bother, and expectation of outcome. Historically, expectant management with catheter drainage for up to 3 months has been used in patients with obstructive voiding symptoms after PVS as 98% resolved without surgical intervention [19]. This is thought to allow sufficient retropubic scarification and fibrosis, which may explain low rates of recurrent SUI after urethrolysis. Longstanding BOO may cause irreversible bladder dysfunction, however, even after successful urethrolysis [60]. Earlier lysis of PVS and MUS (6  ±  3.2 months vs. 33  ±  20.1 months) has been recently shown to be a predictor of overall improvement with no difference in SUI [61]. In our experience, significant incomplete emptying and urinary retention after 4–6 weeks usually requires operative intervention.

Midurethral Sling Incision

This 3-month waiting period is generally not applied to MUSs. After these slings, 66–100% of temporary voiding dysfunction resolves by 6 weeks [5962], and most patients will empty fairly normally after 72 h. If the transvaginal incision of the MUS is conducted within 7–10 days, there is little tissue in-growth into the sling, and the procedure can be done with minimal manipulation. Although this can be done in the office setting under local anesthetic, we prefer the more controlled setting of the operating room where vaginal exposure can be maximized. The vaginal wall is infiltrated with local anesthetic and the suture used to close the vaginal wall is opened. The sling can usually be easily visualized. A right-angle clamp is then placed behind the sling and the sling is loosened by either downward traction or spreading of the right-angle clamp. Caution must be taken to avoid urethral injury when passing the clamp between the urethra and an overtensioned sling. If the sling is already incorporated into the tissue or has been in place for more than 2 weeks, it may be cut in the midline. We prefer to excise the cut ends of the sling as well as remove any suburethral portion to prevent any potential protrusion through the vaginal wall closure rather than leaving them in situ.

Pubovaginal Sling Incision

A more formal transvaginal sling incision is required for PVS. Sling incision has comparable success rates (84–100%) without the longer operative time and potential morbidity of a formal urethrolysis [52586364]. We begin with cystourethroscopy of the urethra, bladder, and bladder neck. A 30° lens scope with a short beak allows examination of the urethra for signs of sling erosion or hypersuspension. The inverted-U vaginal flap is first hydrodissected and then dissected off the pubocervical fascia to the level of the bladder neck. A metal urethral sound or cystoscope can be placed in the urethra to better expose the proximal urethra and area of the sling. The sling is then dissected off the underlying pubocervical fascia such that a right-angle clamp can be placed behind the sling. An Allis clamp placed on the sling and pulled downward can facilitate dissection. If there is too much scarring in the midline to isolate the sling, this can be done laterally. The sling is lifted off the pubocervical fascia and incised. We always perform cystoscopy after any sling manipulation to ensure no urinary tract injury and to assess for residual ­anatomic obstruction.

In patients who fail transvaginal sling incision, urethrolysis can be performed either by a transvaginal or retropubic approach, with success rates ranging from 65 to 84%. Generally, we use transvaginal urethrolysis as a primary procedure, and retropubic urethrolysis as a secondary procedure due to the increased morbidity of the latter. Transvaginal suprameatal urethrolysis has also been described [65]; however, success rates are lower than for the transvaginal and retropubic methods. This technique is not as widely used and will not be described in this section. Success rates and rates of recurrent SUI for transvaginal, retropubic, and suprameatal urethrolysis are outlined in Table 11.2.

Table 11.2

Results of urethrolysis

References

No. of patients

Type of urethrolysis

Time to urethrolysis (months)

Overall success (%)

Rate of stress urinary incontinence (%)

Foster and McGuire [74]

48

Transvaginal

26

65

0

Nitti and Raz [52]

42

Transvaginal

54

71

0

Cross et al. [75]

39

Transvaginal

11

72

3

Goldman et al. [76]

32

Transvaginal

14

84

19

Webster and Kreder [66]

15

Retropubic

8

93

13

Scarpero et al. [62]

24

Retropubic

9

92

18

Petrou et al. [65]

32

Suprameatal

Not reported

67

3

Carr and Webster [54]

54

Mixed

15

78

14

Transvaginal Urethrolysis

An inverted U-shaped anterior vaginal wall flap is created with the apex at the midurethra and base at the bladder neck (Fig. 11.3). The dissection is taken along the plane of pubocervical fascia up to the pubic bone laterally. The endopelvic fascia is perforated sharply with Metzenbaum scissors to enter the retropubic space. Blunt and sharp dissection is used to free the urethra from its attachments to the pubic bone. Any scar or sling encountered in the retropubic space is divided. The urethra is freed proximally to the bladder neck. Occasionally, if adequate vesicourethral mobility cannot be achieved, urethrolysis may be completed from a retropubic approach [62].

A213469_1_En_11_Fig3_HTML.jpg

Fig. 11.3

Transvaginal urethrolysis demonstrating midline incision of synthetic midurethral sling (MUS)

Retropubic Urethrolysis

The technique of retropubic urethrolysis has been described by Webster and Kreder [66]. A low midline or Pfannenstiel incision is made and the retropubic space of Retzius developed. All retropubic and prevesical adhesions are sharply incised and all visible suspension sutures and sling materials are cut. All the attachments to the pubic symphysis are released. If there is significant scarring and fibrosis, the dissection can be extended laterally to the ischial tuberosities, creating a paravaginal defect. If this occurs, a formal paravaginal repair involving reapproximation of the paravaginal fascia to the arcus tendineous fascia pelvis is performed. Adequate vesicourethral mobility is determined by observation of free flow of urine from the urethral meatus on application of a Crede maneuver. In the original description, an pedicled omentum flap is routinely interposed between the urethra and pubic bone to prevent readherence.

Failed Urethrolysis

Persistent obstruction following urethrolysis is thought to be due to inadequate vesicourethral mobilization, recurrent periurethral fibrosis, and retropubic scarring or a concomitant resuspension procedure [67]. Scarpero et al. reported on the efficacy of repeat urethrolysis after failed initial urethrolysis. Twenty-four women with persistent urethral obstruction underwent aggressive dissection to free all periurethral and retropubic attachments. Retropubic urethrolysis was performed in 12 (50%), transvaginal in 10 (42%), and 2 (8%) patients had combined techniques. The success rate was 92% with the recurrent SUI rate of 18% being comparable to other published rates after primary urethrolysis. This supports the use of aggressive repeat urethrolysis after failed primary urethrolysis.

De Novo Urgency

Anti-incontinence surgery may cure or aggravate urge symptoms and lead to de novo urgency and detrusor overactivity. This aspect of anti-incontinence surgery is unpredictable and a major cause of patient dissatisfaction. A meta-analysis of studies from December 2002 to June 2005 of patients undergoing sling surgery without concomitant prolapse repair estimated median rates of de novo urge incontinence to be 9% in PVS groups and 6% in MUS groups [20]; however, the MUS groups were not separated according to route. In the Cochrane review by Ogah and Cody, there was no statistical difference in de novo urgency and urge incontinence between transobturator and retropubic MUS groups in the 14 trials compared (7% vs. 6% respectively, RR 1.08, 95% CI 0.75–1.56) [30], but the confidence interval was wide. These symptoms can persist long term. Kuuva and Nilsson reported a de novo urgency rate of 4.7% in 129 women, 6 years after TVT implantation [68].

It is important to remember that storage symptoms such as de novo urgency, without incomplete emptying, may be a manifestation of urethral obstruction [54]. If diagnosed, relief of obstruction is the primary goal of treatment, while urge symptoms may be alleviated by antimuscarinic therapy. In the absence of obstruction (or any other reversible anatomic cause of the urgency such as sling erosion), initial treatment of urgency and urge incontinence consists of fluid management, timed voiding, and antimuscarinic medications. Most patients will have cure or control of their symptoms with these conservative measures. Refractory cases can be treated with surgical procedures such as sacral neuromodulation and peripheral nerve stimulation, and in more extreme cases, augmentation cystoplasty. Prior to consideration of augmentation, intradetrusor injection of botulinum toxin type A can be trialed.

Erosion/Extrusion

Prior to the recently published ICS/IUGA joint terminology and classification system, the term “erosion” was widely used to indicate the finding of material within the lumen of the urinary tract and “extrusion” referred to the finding of exposed material within the vaginal canal. These terms will be used in this section, to avoid any miscommunication of the published literature.

Erosion

Previous series estimated the urethral erosion rate for autologous slings to be <0.003% and for synthetic slings 0.02% [69]. Updated data suggest a higher erosion rate for synthetic slings between 2 and 4% [20]. Underreporting and variability in terminology likely cause underestimation of this complication in the literature. At our institution, we have noticed an alarming increase in the number of referrals for urinary tract erosions from surgical mesh especially over the last 5 years [70].

Urinary tract erosion can be a devastating complication for patients and in our experience always requires primary surgical management. It is unclear whether erosions represent missed intraoperative perforations into the urinary tract or result from passive migration of the material into the urinary tract postoperatively. Intraoperative cystoscopy during sling surgery is considered standard of care in order to identify intraoperative urinary tract injuries [20]. Potential contributing factors to urethral erosion include compromised urethral blood supply (from radiation or estrogen deficiency), excessive sling tension, extensive dissection too close to the urethra with subsequent devascularization, missed intraoperative urethral injury, and traumatic catheterization or dilation postoperatively.

Patients can present with irritative and obstructive voiding complaints, urinary incontinence, hematuria, recurrent UTIs, and pain. Diagnosis is often delayed; Amundsen et al. reported mean of 9 months from sling placement to diagnosis of urethral erosion [71]. Definitive diagnosis is made endoscopically. Autologous and allograft sling urethral erosion is usually managed with excision of the part of the sling which has eroded and simple closure of the urethra [9]. Synthetic mesh erosions typically mandate open exploration, removal of all the exposed material, closure of the urinary tract, placement of an interposition graft material, and adequate postoperative drainage. Most erosions involve the urethra and bladder walls (Figs. 11.4 and 11.5) and will require a complex surgical approach [70] (Fig. 11.6). Occasionally, small intravesical erosions can be treated with endoscopic scissor or laser excision and/or ablation. In our experience, after initial repair, 40% of patients will require a secondary procedure and two thirds will have incontinence postoperatively [70]. Due to complex nature of these repairs, preoperative counseling should emphasize realistic goals of anatomical and functional outcomes.

A213469_1_En_11_Fig4_HTML.jpg

Fig. 11.4

Cystoscopic view of synthetic MUS erosion into proximal urethra

A213469_1_En_11_Fig5_HTML.jpg

Fig. 11.5

Cystoscopic view of synthetic MUS erosion into lateral bladder wall

A213469_1_En_11_Fig6_HTML.jpg

Fig. 11.6

Transvesical excision of synthetic MUS which was eroded into bladder base

Extrusion

The incidence of extrusion of synthetic slings into the vagina is 2–9% [20]. Extrusions may result from subclinical or overt infection, wound dehiscence, unrecognized vaginal wall perforation, devascularized vaginal flaps, wound compromise secondary to early local trauma (such as early intercourse), or the physical properties of the graft itself. Several earlier types of mesh were taken off the market due to high rates of encapsulation and subsequent extrusion [7273].

Patients are typically symptomatic and may present with malodorous vaginal discharge, vaginal pain, dyspareunia, vaginal spotting, and partner discomfort during intercourse. Patients also frequently report that they can palpate mesh in the vagina. The extruded mesh is often palpable and visible on physical exam and can be associated with granulomatous tissue (Fig. 11.7).

A213469_1_En_11_Fig7_HTML.jpg

Fig. 11.7

Synthetic MUS exposure in vagina

Unlike erosions into the urinary tract, management of mesh extrusion is usually straightforward and is associated with a high success rate and resolution of symptoms. Small extrusions can be initially treated conservatively with the application of topical estrogen creams to promote healing of the vaginal mucosa over the extruded material. These should only be observed for a brief period of time before considering surgical intervention. Larger extrusions and those failing conservative treatment can be treated by raising vaginal flaps and covering the exposed mesh. We prefer to excise the extruded sling before covering the defect with the vaginal flaps to prevent future extrusions.

Recurrent UTI

Four percent to 15% of patients undergoing sling procedures report UTIs [20], and 8% of women undergoing urethrolysis after sling surgery presented with recurrent UTI [54]. However, there are inconsistencies in the detection and reporting of UTI after SUI procedures. A patient presenting after a routine sling procedure with typical symptoms of a UTI such as frequency, urgency, and hematuria should be evaluated with a history, physical exam, urinalysis, and urine culture. Routine dipstick may be difficult to interpret immediately postoperatively, especially if the patient is being catheterized. A short course of antibiotics can be instituted empirically while awaiting culture results.

Patients with severe, ascending, or systemic symptoms (such as abdominal or flank pain, fever) and persistent or recurrent UTI warrant more thorough investigation. This includes a full history, physical exam, and appropriate urine and blood studies including cultures. Cross-sectional imaging and cystoscopy are essential in diagnosing sources of infection such as abscess, upper urinary tract obstruction, stones, foreign bodies, erosion of slings, or other occult bladder diseases. Postvoid residual measurement and urodynamic studies can be used to rule out obstruction as a cause of the recurrent UTI.

Conclusion

Sling surgeries for female SUI are widely performed with generally high rates of success and low rates of morbidity and mortality. Complications from these procedures are likely underreported in the literature because of variability of definitions, lack of mandatory reporting vehicles, and the need for studies with longer follow-up. Enthusiasm for minimally invasive MUSs have substantially increased the number of sling surgeries performed, as well as increased the number of and variability in the practitioners implanting these devices. Many complications can be prevented by first ensuring that the indication for the particular type of sling is appropriate, and second, by adhering to good surgical technique. Patients must be well counseled preoperatively about all the potential risks of the procedure, as well as the realistic expected outcomes. Practitioners should remain attentive to patient symptoms postoperatively, in order to promptly identify potential complications.

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