Periurethral and Transurethral Bulking Agents
Christopher E. Wolter
Introduction
Stress urinary incontinence (SUI) has been and will continue to be a significant problem for women worldwide. It can affect women of a variety of ages and activity levels through several etiologies. Peak prevalence rates for any SUI are seen in women between ages 40 and 59 years according to the International Consultation on Incontinence (ICI), indicating that this is not only a problem for the frail or elderly.1 There is a significant economic impact as well from direct treatment costs within the health care system as well as indirect costs borne by individual women. There can also be significant emotional and social effects seen in women as SUI can frequently alter normal activity and interactions.2
After failed conservative management, patients frequently desire more definitive procedural therapy. Surgical treatment options vary widely for this condition and can range from invasive (pubovaginal slings and colposuspensions), to minimally invasive (midurethral slings [MUS] and bulking agent injections), of which MUS are now the most commonly performed surgical procedures.3 Bulking agents are attractive for women because of their low risk, endoscopic, minimally invasive nature. Given ongoing apprehension regarding the use of polypropylene mesh, they appeal even further.4,5 This is especially true for those who do not desire to undergo more invasive surgery.
BULKING AGENTS
Bulking agents for SUI are space-occupying injectable substances that can be performed in the office or operating room setting. They are made of a variety of substances, both biologic and synthetic, particulate and nonparticulate.4 The goal of bulking agent injection therapy is to increase urethral resistance and the overall inherent seal effect of the urethra through submucosal deposition of these substances in the proximal urethra by likely increasing the functional length of the continence mechanism.6 The end result should allow for increased intraurethral pressure and urethral coaptation at rest and during Valsalva maneuvers, yet still allow for flow through the urethra at the time of voiding.5,7
The ideal bulking agent should have the following properties: biocompatibility, nonantigenicity, cause minimal reaction, encapsulation, or inflammation. Additionally, there should be minimal degradation or migration.7 There should also be a prolonged duration of treatment effect. There has not been an ideal agent produced yet. That being said, there are several agents available for use that combine one or more, but not all, of these ideal properties. There does not appear to be an obvious advantage to any one of the bulking agents currently commercially available over another.8
PATIENT SELECTION
The ideal patient candidate for bulking agent injection should be one who is willing to accept lower success rates in exchange for ease of application. Patients declining pelvic floor physical therapy, incontinence pessary, and those with a fixed urethra due to prior surgery or radiation are also candidates. Urethral mobility in women does not appear to influence the success of bulking agents.9 However, some suggest hypermobility may influence relative success with these agents, or infer other suspension therapies would be superior in those otherwise not well supported.5,10 In these patients, ideally, they would be treatment failures with sling or suspension surgery but who have a well-supported urethra with continued intrinsic sphincter deficiency (ISD).11,12 Additional considerations for treatment with bulking agents include those who cannot discontinue anticoagulant medications, women of childbearing age who desire more children in the future, those who are poor candidates for other surgical therapies, and those who are at high risk for urinary retention.5
Patients undergoing urethral bulking injections need to be counseled about several things. First, they should be told that this treatment is likely not as effective as sling surgery in overall efficacy in treating their SUI. They should also be told that they likely will need more than one treatment to either achieve or maintain optimum
results and that they may not be able to achieve complete continence with this therapy. Overall, long-term data regarding this therapy is lacking. Patients should be counseled that regarding the specific agents available, there is no data to necessarily support the use of one agent over another, as few head to head studies have been performed. Management of patient expectations should incorporate all these points.5,7,8,10 Finally, patients should be counseled that while uncommon, complications can occur with bulking agent injections, although most are minor and self-limited. However, serious complications have been reported over the years, requiring more invasive surgical interventions for management.13
results and that they may not be able to achieve complete continence with this therapy. Overall, long-term data regarding this therapy is lacking. Patients should be counseled that regarding the specific agents available, there is no data to necessarily support the use of one agent over another, as few head to head studies have been performed. Management of patient expectations should incorporate all these points.5,7,8,10 Finally, patients should be counseled that while uncommon, complications can occur with bulking agent injections, although most are minor and self-limited. However, serious complications have been reported over the years, requiring more invasive surgical interventions for management.13
Conventional teaching warns against the use of injectable agents in patients with a history or previous radiation therapy (RT) for pelvic cancers, but there is evidence to refute this. Patients with a history of previous pelvic RT are considered poor bulking candidates due to poor tissue quality and stiffness of the urethral layers, making coaptation of the urethra difficult as a result.7 However, in a review by Dobberfuhl,14 bulking agents were described as the only incontinence treatment studied in a prospective fashion specifically in radiated women, and although not randomized, had the highest level of evidence. In one trial, Krhut et al.15 compared two groups treated with polyacrylamide hydrogel, with one group having previous RT, and the other was radiation naïve. Although the RT patients did not have quite as good of an outcome as the nonradiated group, the differences were nonsignificant for several parameters and they concluded that bulking therapy is valuable for radiated patients.
INJECTION PROCEDURE
Patient Preparation
General considerations apply to all periurethral injection procedures. Patient counseling should be done as outlined in the previous section. The setting of expectations cannot be minimized given the repetitive nature of these treatments, and if patients want something more definitive, they should seek another therapy. They should be counseled regarding the possibility of urinary retention and its management. They should also be told it is normal to have dysuria, hematuria, urgency, and frequency after the procedure and that there is a possibility for infection afterward. A preprocedure urine culture should be obtained and treated and repeated as appropriate. If a patient has a history of hypersensitivity or allergy to any of the injectable components, that particular agent is contraindicated. One of the most commonly used agents before it was discontinued, Contigen (glutaraldehyde cross-linked bovine collagen), actually required a skin test 30 days prior to treatment to rule out allergy to this xenographic agent. This point is largely historical at this time, however.7,10
Injection Techniques
Urethral bulking agents can be administered by either a transurethral or periurethral injection technique. For either procedure, they can be done under local anesthesia or under general anesthesia/sedation per the preference of the surgeon and patient. Both techniques use cystoscopic guidance in order to visually confirm the correct location of injection of the agent in use. The main difference lies with where the needle is inserted, and there can be advantages to both techniques. The transurethral technique is purported to allow for better visualization of the injection site, thus allowing for more precise placement of the agent, whereas the periurethral route is less likely to result in extravasation of the material due because there is no puncture of the urethral lumen in this case. Ultrasound guided techniques have also been described.4,5,7,10
Transurethral injection technique
The patient is placed in the dorsal lithotomy position and should be prepped and draped using sterile technique. Local anesthesia in the form of lidocaine jelly given intraurethrally should be administered next, if the patient is awake, and given proper dwell time for effect. Optionally, a periurethral block can be used here as well (Fig. 32.1). Using a rigid cystoscope, it should first be advanced into the bladder and the bladder should be drained completely. With a 30° lens, the injection needle should then be advanced into view and then the scope is then withdrawn into the urethra and the location of the midproximal urethra should be noted. The needle is deflected 30° to 45° and starting at the lateral position (3 or 9 o’clock), is placed against the mucosa until it indents slightly. The scope and needle are then advanced
until the needle pierces the mucosa and advances a slight amount in the submucosal space. Care should be taken that the needle insertion site is not too proximal on the urethra so that when it is advanced it does not continue into the lumen of the bladder.5,7,10
until the needle pierces the mucosa and advances a slight amount in the submucosal space. Care should be taken that the needle insertion site is not too proximal on the urethra so that when it is advanced it does not continue into the lumen of the bladder.5,7,10
 FIGURE 32.1 Periurethral bulking technique with periurethral block. Injection of local anesthetic lateral to Skene duct openings. (Reprinted from Bent AE. Periurethral collagen injections. Oper Tech Gynecol Surg 1997;2:52. Copyright © 1997, with permission from Elsevier.) |
 FIGURE 32.2 Transurethral needle placement in urethral submucosa. (Reprinted from Bent AE. Periurethral collagen injections. Oper Tech Gynecol Surg 1997;2:54. Copyright © 1997, with permission from Elsevier.) |
Without moving the position of the needle, the bulking agent can then slowly be injected in an amount sufficient to cause a mass effect akin to coaptation (Fig. 32.2). This process is then repeated on the opposite side and when injecting the agent, the end result should show good urethral coaptation in the proximal portion of the urethra (Fig. 32.3). Advancing the scope back into the bladder should be avoided so as to not crush, distort, or cause extravasation of the injectable agent that has just been administered.7,10
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