Stress Urinary Incontinence
Victoria L. Handa
DEFINITIONS
Cotton swab test—Measure of urethral mobility; with the patient in supine lithotomy position, a lubricated cotton swab (or other similar device) is placed into the urethra, allowing a measurement of the rotational descent of the bladder neck with Valsalva; an angle of >30 degrees (with respect to the horizontal) is classically defined as a hypermobile urethra.
Cystometry—Tests of the pressure/volume relationship during bladder filling; “simple” cystometry is a manometric evaluation, while “complex” cystometry involves an electronic measurement and recording of bladder pressure during filling, often with simultaneous measurement of intra-abdominal pressure (and sometimes urethral pressure).
Intrinsic sphincter deficiency (ISD)—Urinary incontinence that is due to dysfunction of the urethral sphincter mechanism, presumably related to loss of smooth muscle tone and/or coaptation of the urethral lumen.
Occult stress incontinence—Stress incontinence only observed after the reduction of coexistent prolapse (e.g., after surgical correction of prolapse).
Stress urinary incontinence—The symptom of involuntary leakage of urine from the urethra at the time of increased intra-abdominal pressure (e.g., coughing, straining).
Urethral hypermobility—Descent of the bladder neck with increased intra-abdominal pressure, typically defined as a cotton swab angle greater than 30 degrees from the horizontal.
Urodynamic stress incontinence—The involuntary leakage of urine during filling cystometry, associated with increased intra-abdominal pressure, in the absence of a detrusor contraction.
Urinary incontinence is a condition that affects 30% to 40% of older American women, with the majority afflicted with stress urinary incontinence (SUI). The management of SUI has changed dramatically over the past two decades, due in part to the introduction of synthetic midurethral slings and due also to the accumulation of evidence from clinical trials to guide therapy. Surgeries that were once the standard of care, such as Pereyra needle suspensions and anterior colporraphy with Kelly placation, are now known to be less effective than are other options and are therefore no longer recommended for treatment of SUI.
The phrase “stress urinary incontinence” is used to refer to a symptom, a physical finding, and a urodynamic diagnosis. The symptom of SUI is the complaint of involuntary loss of urine on effort or physical exertion (e.g., exercise), or on sneezing or coughing. The sign of SUI is the observation, on physical examination, of incontinence from the urethra synchronous with effort similar provocation, such as coughing. Urodynamic stress incontinence is defined as the involuntary leakage of urine during increased abdominal pressure in the absence of a detrusor contraction.
INITIAL EVALUATION
The history and physical examination are critical in the assessment of SUI. Typically, a thorough history will distinguish SUI from other types of urinary incontinence. The initial assessment should also include an evaluation of the impact of SUI on quality of life, as treatment is indicated only if the woman considers her symptoms to be bothersome or to interfere with her activities. Other goals for the initial assessment include the identification of other factors that could exacerbate or precipitate symptoms, such as neurologic disease, polyuria, and many medications (especially those with effects on the autonomic nervous system). A voiding diary may be appropriate to assess normal voiding habits. The physical examination should include a measure of postvoid residual. Laboratory studies can be limited to screening for urinalysis to exclude hematuria and pyuria.
Among women planning surgical treatment of SUI, urethral hypermobility should be assessed on physical examination. A variety of methods can be used to assess urethral mobility, although this is traditionally evaluated with a cotton swab test. For this test, a lubricated cotton swab is inserted into the urethra with the patient in the supine lithotomy position (Fig. 41.1). As the patient strains or coughs, the angle formed by the cotton swab with respect to the horizontal is measured. Women with a straining cotton swab angle of at least 30 degrees above the horizontal are said to have a hypermobile urethra. Most women with SUI will have evidence of a hypermobile urethra, but it is important to note that a hypermobile urethra is neither necessary nor sufficient for the diagnosis of SUI. However, this finding has been associated with surgical outcomes, and it is therefore important to assess patients for urethral hypermobility if surgery is planned.
 FIGURE 41.1 The cotton swab test demonstrates a resting angle close to 0 degrees and a straining angle of approximately 40 degrees. A straining angle greater than 30 degrees above the horizontal is considered “hypermobile.” (Reprinted from Bent AE, Cundiff GW, Swift SE. Ostergard, Ostergard’s urogynecology and pelvic floor dysfunction, 6th ed. Philadelphia, PA: Lippincott, Williams & Wilkins, 2007, with permission. Copyright © 2007 Wolters Kluwer Health.) |
TABLE 41.1 Criteria for Surgical Management of Stress Urinary Incontinence without Urodynamic Evaluation | |
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Urodynamic investigation, including cystometry, has historically played an important role in the preoperative assessment of women with SUI. The goals of urodynamic investigation are to confirm the diagnosis of SUI and to exclude conditions that could either impact the success of therapy or signify an increased risk of adverse outcomes. However, many women with uncomplicated SUI may not benefit from testing. Those unlikely to benefit from testing (Table 41.1) include women with clear symptoms of SUI in the absence of significant urge-related symptoms, a postvoid residual volume less than 150 mL, a hypermobile urethra, and a positive “stress test” (visual evidence of urine loss with cough or Valsalva). In general practice, most women with SUI probably meet these criteria and can therefore be managed without urodynamic testing. However, in a tertiary setting, Nager and colleagues found that only 1,375 of 4,083 women with SUI (33%) fell into this “low-risk” category. Indications for urodynamic testing or referral to a specialist include those who do not meet the criteria above; those with a history of prior anti-incontinence surgery, prior radical pelvic surgery, or radiation; and those with neurologic disease. Cystoscopy may also be indicated in the evaluation of women with these risk factors.
There is controversy surrounding the value of preoperative assessment for “intrinsic sphincter deficiency (ISD)” in women with SUI. This concept refers to a poorly functioning urethra. The contemporary view is that urethral function is a spectrum and that all women with SUI have at least some component of poor urethral function. In theory, the “intrinsic” sphincter function of the urethra is provided by smooth muscle tone and coaptation of the urethral lumen. Thus, presumably, ISD is related to a deficiency in one or both of these continence mechanisms. Some experts argue that women with SUI who do not have urethral hypermobility must have ISD. Others consider ISD to be a measure of more severe SUI (measured either by symptom severity or with a leak point pressure, an indication of the ease with which SUI is demonstrated on physical examination). Yet a third classification scheme assigns a diagnosis of ISD in cases of low urethral closure pressure or an “open” bladder neck at rest (e.g., during urethroscopy or contrast imaging; Fig. 41.2). With contemporary treatment of SUI, the distinction between ISD and other types of SUI has become less important. It is not clear that the diagnosis of ISD has an impact on the management of SUI.
 FIGURE 41.2 Photograph from urethroscopy, illustrating a functionless urethra. The bladder neck is passively open at rest. In a woman with stress incontinence, this appearance may signify intrinsic sphincter deficiency. (Reprinted from Bent AE, Cundiff GW, Swift SE. Ostergard, Ostergard’s urogynecology and pelvic floor dysfunction, 6th ed. Philadelphia, PA: Lippincott, Williams & Wilkins, 2007, with permission. Copyright © 2007 Wolters Kluwer Health.) |
INITIAL MANAGEMENT
Randomized clinical trials have demonstrated the effectiveness of anti-incontinence pessaries and pelvic muscle physical therapy. Conservative therapy helps a large number of these patients. However, a recent multicenter trial by Richter and colleagues suggested that only 50% of women with SUI will be satisfied with the outcome of these nonsurgical approaches. Nevertheless, all women with bothersome SUI should be offered nonsurgical options. Surgery should be reserved for women who decline or fail nonsurgical therapies.
SURGICAL TECHNIQUES FOR THE TREATMENT OF STRESS INCONTINENCE
More than 200 procedures have been described in the literature for the treatment of stress incontinence. This reflects a combination of the evolution of established and effective procedures as well as the introduction of newer technologies and materials. Most of these surgeries, including the anterior colporraphy with Kelly placation and Pereyra needle suspensions, are now of historical interest only. This chapter focuses on retropubic and transobturator midurethral sling procedures, which have become the mainstays of surgical therapy for SUI. Other options, appropriate for selected populations, include the retropubic urethropexy, rectus fascia suburethral sling procedures, and the injection of bulking agents. These also are addressed.
Retropubic Midurethral Sling Procedures
The retropubic midurethral sling was first described by Ulmsten and colleagues. The appeal of a tension-free midurethral sling is that it is an effective, minimally invasive technique that can be applied to a day-surgery setting. Thus, this approach was an important innovation when it was introduced in the 1990s.
The patient is typically positioned in low lithotomy, with Allen stirrups (Fig. 41.3). The bladder is emptied with an 18-F catheter. Suprapubic sites are marked approximately 2 to 3 cm lateral to the midline. These sites are selected to be medial to the pubic tubercle; they represent the lateral boundary for safe perforation of the abdominal wall. More lateral sling placement will increase the risk of neurovascular injury.
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A 1- to 2-cm incision is made under the midurethra (Fig. 41.4A). Typically, the distal aspect of the incision is 1 to 1.5 cm from the urethral meatus. The midurethral location can be confirmed via palpation of the Foley bulb while gentle traction is placed on the Foley. After the creation of the incision, a 2-cm tunnel is made with Metzenbaum scissors at a 45-degree angle toward the descending pubic ramus on each side (Fig. 41.4B). Minimal vaginal dissection is recommended to limit bleeding from the paraurethral vascular plexus, to maintain the sling in its position under the midurethra (e.g., minimizing the probability that it will be displaced to the proximal or distal urethra), and to minimize the risk of mesh exposure.
Some surgeons inject the vaginal wall and retropubic space with a dilute solution of local anesthetic (such as a 3:1 dilution of 1% xylocaine or ¼% bupivacaine). A spinal needle is advanced through the abdominal wall, immediately along the pubis, and into the retropubic space. Traditionally, 5 to 10 mL of solution is injected suprapubically on each side. Then, 10 mL
of the solution is placed in the retropubic space bilaterally by a vaginal approach. The needle is advanced through the vaginal incision and under the vaginal epithelium, injecting small amounts along the intended path of the sling trocar, entering the retropubic space at the junction of the descending pubic ramus and the pubis. Five to ten milliliters is placed on each side. Injection of saline or local anesthetic into the retropubic space (“hydrodissection”) is thought to distend the space, facilitating safe placement of the trocars. Some experts prefer injections of saline (for hydrodissection of the retropubic space) rather than a local anesthetic. This is because the benefits of local anesthetic injection are limited to the first few hours after surgery.
of the solution is placed in the retropubic space bilaterally by a vaginal approach. The needle is advanced through the vaginal incision and under the vaginal epithelium, injecting small amounts along the intended path of the sling trocar, entering the retropubic space at the junction of the descending pubic ramus and the pubis. Five to ten milliliters is placed on each side. Injection of saline or local anesthetic into the retropubic space (“hydrodissection”) is thought to distend the space, facilitating safe placement of the trocars. Some experts prefer injections of saline (for hydrodissection of the retropubic space) rather than a local anesthetic. This is because the benefits of local anesthetic injection are limited to the first few hours after surgery.
 FIGURE 41.3 Positioning the patient in Allen universal stirrups to allow vaginal and abdominal access. |
 FIGURE 41.4 A: The vaginal incision for a midurethral sling procedure is approximately 1.5 cm in length and is located at the midurethra, typically 1 to 1.5 cm from the urethral meatus. B: For a retropubic midurethral sling, fine scissors are used to dissect a subepithelial tunnel, typically 2 cm in length. The angle of the tunnel is typically at 45 degrees, aimed toward the junction of the descending pubic ramus and the pubis. |
Commercially available midurethral slings consist of a polypropylene strap and rigid trocars for insertion (Fig. 41.5). Prior to placement of the trocar, a rigid catheter guide is placed through the 18-F catheter. Using the rigid guide, the bladder can be directed away from the side on which the surgeon is working, so as to minimize the risk of bladder injury. The retropubic sling is passed into the retropubic space using the curved trocar (Fig. 41.6). A knowledge of retropubic anatomy is critical to the safe placement of the sling. The trocar should be advanced into the retropubic space at the junction of the descending pubic ramus and the pubis, immediately along the inferior surface of the bone. This is a relatively avascular zone of the retropubic space (Fig. 41.7). If the trocar perforates in this location, the trocar will be lateral to the retropubic branches of the internal pudendal vessels and medial to the inferior epigastric, obturator, and accessory obturator vessels. If the trocar is directed away from the surface of the bone, a bladder perforation is more likely, as is an injury to branches of the perivesical venous plexus and vesical vessels. The pubic veins, branches of the obturator vessels that course medially along the ventral surface of the pubis, are the only vessels likely to be along the path of the needle placed in this fashion. After initial insertion through vaginal wall, the trocar may also pass close to (or through) the paraurethral vascular plexus, which arise from the internal pudendal and superior vesical arteries. Shobeiri found that injury to these paraurethral vessels is likely, but the related bleeding is of limited clinical significance and can typically be controlled by pressure or vaginal packing. He recommended minimal vaginal dissection to reduce risk of significant bleeding from the paraurethral vessels.
As the trocar is passed into the retropubic space, it hugs the pubic ramus as the endopelvic fascia is penetrated and then is advanced until the tip appears suprapubically, immediately
medial to the site previously marked (Fig. 41.8). The needle tip is passed just through the skin. The tape is passed on the opposite side using a similar technique. Cystoscopy is performed after each pass or, alternatively, after both passes have been made (Fig. 41.9). If there is no bladder perforation, the needles are advanced and pulled completely through the abdominal wall. The needles are detached from the sling device. The sling with protective sheath is tightened over a number 9/10 Hegar dilator or other instrument, which is held in place until the sling is secured. The plastic sheaths are pulled free from the mesh, and excess sling material is cut flush to the skin surface. At this point, the Hegar dilator can be removed. The vaginal and skin incisions are closed. The sling is not sutured to any underlying tissue, and the composition of the mesh allows tissue ingrowth to fix the sling in place.
medial to the site previously marked (Fig. 41.8). The needle tip is passed just through the skin. The tape is passed on the opposite side using a similar technique. Cystoscopy is performed after each pass or, alternatively, after both passes have been made (Fig. 41.9). If there is no bladder perforation, the needles are advanced and pulled completely through the abdominal wall. The needles are detached from the sling device. The sling with protective sheath is tightened over a number 9/10 Hegar dilator or other instrument, which is held in place until the sling is secured. The plastic sheaths are pulled free from the mesh, and excess sling material is cut flush to the skin surface. At this point, the Hegar dilator can be removed. The vaginal and skin incisions are closed. The sling is not sutured to any underlying tissue, and the composition of the mesh allows tissue ingrowth to fix the sling in place.
 FIGURE 41.5 Vaginal approach for tension-free vaginal tape procedure. Gynecare TVT Obturator System Tension-Free Support for Incontinence. Materials include a catheter guide to retract the bladder away from the working area, the tape material attached to two insertion needles, and the handle to attach to the needles for insertion. (Copyright © Ethicon, Inc. 2010-2013. Reproduced with permission). |
 FIGURE 41.6 With the rigid catheter guide deviating the bladder to the left, the curved trocar is inserted in the retropubic position. The trocar perforates the retropubic space at the junction of the descending pubic ramus and the pubis, immediately along the surface of the bone. |
Anatomic studies have identified several techniques that minimize the risk to obturator and iliac vessels. For example, during passage of the retropubic trocars, the surgeon should not laterally divert the tip of the trocar; rotation of the trocar is a safer technique. Shobeiri demonstrated that if the surgeon rotates the needle without lateral diversion, injury to the external iliac vessels cannot except in cases of extreme rotation (>75 degrees). Injury may be increased if the trocar is both laterally diverted and rotated. The surgeon should also be familiar with the corona mortis, an anastomosis between the obturator and inferior epigastric vessels. This anastomosis is typically greater than 6 cm lateral to the midline and is reliably 3 cm lateral to the midline. Experienced retropubic surgeons are aware that this anastomosis is almost invariably present in a fat pad at the lateral aspect of Cooper ligament. Injury to the corona mortis can easily be avoided if the trocar does not pass more than 3 cm lateral to the midline. Finally, Rahn and colleagues have shown that perforation of the pubococcygeus muscle can occur if the retropubic trocar is deviated laterally (Fig. 41.10), although perforation of the muscle is of uncertain consequence.
A vaginal pack is not usually placed unless there has been considerable bleeding. A Foley catheter is placed, or, alternatively, the patient may go to recovery without a catheter. A voiding trial is initiated in the recovery room; if the patient cannot void adequately, she performs self-catheterization, or a Foley catheter is placed. In the first week after surgery, voiding dysfunction is common. Patients discharged with an indwelling Foley catheter are scheduled to return to clinic for assessment of voiding function. About half of patients will void adequately by the time of discharge from day surgery. Of those who require catheterization, many are voiding well by the following day, and almost all have recovered normal voiding function within the first week.
 FIGURE 41.7 Retropubic trocars in the space of Retzius. The trocars enter the retropubic space approximately 2 to 3 cm from the midline. In this position, they are medial to the inferior epigastric, obturator, and accessory obturator vessels. The pubic branches of the obturator vessels are seen to course medially along the surface of the pubis. |
 FIGURE 41.8 Insertion of vaginal tension-free tape. A: Vaginal guidance of needle under descending pubic ramus along back of symphysis. B: Pressure over the skin of the abdomen to allow the needle to penetrate the abdominal skin. C: Both needles passed through retropubic space and resting on the abdomen. (Te Linde, Fig. 37.10; With permission: Klutke J, Klutke C. The promise of tension-free vaginal tape for SUI. Contemporary Urology®Archive. 2000; October: Figures 4, 6, and 7.) |
 FIGURE 41.9 Cystoscopy is performed with the retropubic trocar in place. (Reprinted from Zubke W, Gruber IV, Gardanis K, et al. Tension-free vaginal tape (TVT): our modified technique—effective solutions for postoperative TVT correction. Gynecol Surg 2004;1:111, with permission. Copyright © 2004, Springer-Verlag Berlin/Heidelberg.) |
The success rate of the retropubic midurethral sling is approximately 85%. Risk factors for failure include prior incontinence surgery, coexistent urge incontinence, and the absence of preoperative urethral hypermobility. Age also appears to be a risk factor for persistent SUI symptoms. Urodynamic parameters, such as low maximum urethral closure pressure and leak point pressure, may reduce objective success of midurethral slings; however, the predictive value of these parameters is relatively poor.
 FIGURE 41.10 Retropubic space illustration showing location a retropubic sling. The sling on the right passes lateral to the arcus tendineus fascia pelvis (ATFP), perforating the levator ani muscle complex. The sling on the left is in the more typical location, medial to the ATFP. (Reprinted from Rahn DD, Marinis SI, Schaffer JI, et al. Anatomical path of the TVT: reassessing current teachings. Am J Obstet Gynecol 2006;195;1809, with permission. Copyright © 2006, Elsevier.) |
The most serious complications from the retropubic midurethral sling procedure pertain to the percutaneous passage of the trocar (Table 41.2). There have been rare deaths from undiagnosed bowel perforation. Major vascular injury is rare and will be minimized by ensuring that the insertion needle does not stray laterally. Smaller venous channels are frequently penetrated and are managed by pressure for 5 minutes or placement of a vaginal pack. Occasionally, a retropubic space hematoma will develop, but it is self-limited, and the usual treatment is observation.
Bladder perforation occurs in 2% to 4%; the incidence decreases with surgeon experience. Once identified, this event is usually managed by withdrawal and reinsertion of the needle (Table 41.3). When this occurs, a Foley catheter is recommended for bladder drainage. The optimal duration for bladder drainage in this setting is not known. Assuming that the sling is replaced after a perforation, it is our practice to continue drainage for 1 week, given that the perforation is almost always adjacent to the permanent implant. Bladder perforation may be minimized by hydrodissection of the retropubic space, keeping the bladder empty and directing the bladder away from the operative site with the rigid catheter guide.
There is a 2% to 3% risk of persistent urinary retention requiring sling revision. This is best performed in the first 4 to 6 weeks after surgery (e.g., before advanced scarring around the mesh). Sling revision includes exposure of the sling by sharp dissection, with midline transsection to allow retraction of the mesh away from the underside of the urethra. In some cases of retention, the tape will be found to have migrated somewhat proximally along the urethra. After sling transsection, continence is maintained in most patients, and the release of the sling allows normal voiding in most cases.
De novo urinary urgency occurs in 10% to 12%, although this symptom is typically self-limited. However, a number of patients require medical intervention. Release or loosening of the sling may help resolve severe urgency symptoms.
Exposure of the permanent sling material is a delayed complication, occurring in approximately 4% of patients within 24 months. Possible symptoms include bleeding, discharge, and dyspareunia. This complication is usually managed by excision of the exposed mesh and resuturing of the vagina.
TABLE 41.2 Reported Major Tension-Free Vaginal Tape Complicationsa Based on 500,000 Cases | |||||||||||||||||||||||||||||||||||||||||||||
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