Urethral Injection of Bulking Agents for Intrinsic Sphincter Deficiency

18 Urethral Injection of Bulking Agents for Intrinsic Sphincter Deficiency



Alfred E. Bent



INDICATIONS AND CONTRAINDICATIONS 227

EVALUATION 228

Materials 228

TECHNIQUES 229
Periurethral Method 229

Transurethral Method 229

Insertion Devices 230

Post-Injection Follow-up 230

COMPLICATIONS 230

SAFETY 231

EFFECTIVENESS 231

FUTURE CONSIDERATIONS 232

In 1938 Murless reported the use of morrhuate sodium for injection management of urinary incontinence. Since the use of injectable polytetrafluoroethylene (PTFE) in the 1970s for treatment of urinary incontinence, a number of materials for this purpose have gradually emerged. The ideal material is biocompatible, nonimmunologic, and hypoallergenic. It retains its bulking characteristics for a prolonged interval and therefore should not biodegrade or migrate (particle size over 80 μm). The material should be easy to prepare and easy to inject, and the ideal material is safe, readily obtainable, inexpensive, efficacious, durable, and induces minimal tissue reaction. The theory on how injectable materials treat incontinence is by mucosal coaptation with subsequent increased urethral resistance to outflow of urine. Although transmission of pressure to the urethra during increased intra-abdominal pressure may not occur in these patients, the pressure forcing the urine from the bladder through the urethra is resisted by the bulking of the mucosa in the immediate proximal urethra. This essentially prevents involuntary bladder neck opening.



INDICATIONS AND CONTRAINDICATIONS


The ideal patient for urethral bulking has both limited mobility of the bladder neck and a poorly functioning sphincteric mechanism. More often she is older; because repeat injections are usually required over time to maintain effect, this could mean many injections in a young patient. Although some reports indicate equal effectiveness in patients with hypermobility of the bladder neck, others have noted that bulking is not as effective in these patients. The Medicare guidelines for reimbursement were first published in 1994 and then revised in 1996, and indicated that immobility of the bladder neck had to be present. It was not specified as to how immobility was to be determined, but most physicians use a Q-tip test with a straining value of less than 30 to 40 degrees as the cutoff value for hypermobility. In one study, hypermobility was determined radiologically by a standing stress test with 2 cm or greater descent of the bladder neck determined to be hypermobile. The other requirement was initially a leak point pressure of 65 cm H2O or less that was later changed to 100 cm H2O. The measurement of leak point pressure required at least 150 mL of bladder filling, but no requirement was present regarding position of the patient, size of urethral catheter, or kind of effort used to increase the intra-abdominal pressure. One standard method is to do the test in the sitting position, with 200 mL in the bladder, using an 8-French catheter, and asking to patient to gradually strain harder and harder until urine leakage is observed.


Certain patients respond better to periurethral bulking. Should the procedure provide no relief after two injections, subsequent ones are usually futile. A suburethral sling can be performed after periurethral bulking without concern for residual material. It may be preferable to use a nonsynthetic sling in those patients who have bulking agents that do not biodegrade, although no study has shown this. If a surgery has first been performed, either an anti-incontinence procedure or other pelvic floor surgery, and stress incontinence persists or recurs, no contraindication to using a bulking agent is known, and often it is very effective. This may be done as early as 6 weeks after surgery.


As stated, bulking agents are not generally indicated for patients with urethral hypermobility. In some cases in high-risk patients with prolapse and stress incontinence, a pessary has provided excellent control of pelvic organ prolapse, and some temporary stabilization of bladder neck mobility has been present. Periurethral bulking may be used in this patient to treat the potential stress incontinence that was unmasked after the prolapse was reduced.


Contraindications to the use of periurethral bulking include active urinary tract infection, high residual urine (>100 mL), severe detrusor overactivity, and reduced bladder capacity (<250 mL). Periurethral bulking can be done after radiation therapy, but results have not been encouraging.



EVALUATION


Evaluation before therapy includes a history, physical examination, neurologic screen, 24-hour voiding diary, postvoid residual urine determination, and urinalysis and/or culture. A cystometrogram with leak point pressure determination and cystoscopy complements this. The procedure needs to be fully explained to the patient, including the predicted effectiveness and the probable need for repeat injections.



MATERIALS (see Box 18-1)


Contigen (C R Bard Inc., Covington, GA) was approved by the U.S. Food and Drug Administration (FDA) in Washington, DC, in 1993. The material is prepared by a glutaraldehyde cross-linking of bovine dermal collagen, which is dispersed in phosphate-buffered physiologic saline that may comprise up to 65% of the total volume. The material contains 95% of type I collagen and 1% to 5% of type III collagen. It requires a skin test to be placed 30 days before injection to ensure absence of an allergic response, which occurs in 2% to 5% of women. The material biodegrades in 3 to 19 months, which is why repeat injections are usually required to maintain efficacy. However, patients have been satisfactorily managed by one injection for as long as 6 years. The material is readily available and was the only injectable agent approved in the United States until 1999. The material comes in 2.5-mL syringes; injects through a 22-gauge needle; and requires one to three syringes injected transurethrally, and more as a periurethral injection.



BOX 18-1 INJECTABLE AGENTS IN NORTH AMERICA

































Trade Name Company Approval
Contigen CR Bard Inc., Covington, GA 1993
Durasphere EXP Carbon Medical Technologies Inc., St. Paul, MN 1999
Tegress CR Bard Inc., Covington, GA 2005
Macroplastique Uroplasty BV, Geleen, The Netherlands FDA trials ongoing
Zuidex Q-Med AB, Uppsala, Sweden FDA trials ongoing
Coaptite Bioform Medical Inc., San Mateo, CA 2006

Durasphere (Carbon Medical Technologies Inc., St. Paul, MN) was approved by the FDA in 1999. It consists of pyrolytic carbon-coated zirconium oxide beads suspended in a water-based carrier gel containing beta glucan. The newer preparation (Durasphere EXP) has a particle size of 95 to 200 μm compared with the older material that had particle size of 251 to 300 μm. The material is nonbiodegradable, is radiopaque, and requires injection with an 18-gauge needle. The material comes in 1-mL syringes and requires 2 to 4 syringes for injection.


Tegress (CR Bard Inc., Covington, GA) is an ethylene vinyl copolymer dissolved in dimethyl sulfoxide (DMSO) that was recently approved by the FDA. Upon contact with a liquid medium, diffusion of DMSO occurs, and a solid polymer precipitates. It comes in 1-mL syringes, and up to 2.5 mL of material can be injected at a total of three sites, with no more than 1 mL at any one site.


Calcium hydroxylapatite (Coaptite; Bioform Medical Inc., San Mateo, CA) consists of 100-μm hydroxylapatite spheres suspended in an aqueous gel of sodium carboxylmethylcellulose. The material is a natural constituent of bones and teeth and has been used in dental and orthopedic applications for several years. Calcium hydroxylapatite was approved for clinical use in the United States by the FDA in 2006. It is injected via a 21-gauge needle, requires only 2.5 mL on initial injection, and can be visualized radiographically or by ultrasound. The best materials will probably come from tissue engineering and autologous cell bioimplants. This was briefly studied in the past by the use of autologous ear cartilage and in vitro expansion of cells for implant. The technology was not advanced because of cost and use of other readily available and cheaper products.


Macroplastique (Uroplasty BV, Geleen, The Netherlands) is approved for use in Europe but remains in study protocols in the United States. The material is made from highly textured polydimethyl-siloxane macroparticles suspended in a bioexcretable carrier hydrogel of polyvinylpyrrolidone. It consists of silicone microimplants of 73 to 100 μm and is prepared in 2.5-mL syringes. It requires a special injection apparatus for transurethral injection, but it recently has been applied periurethrally by use of an implantation device. The silicone name will most likely inhibit ease of approval in the United States.


Zuidex gel (Q-Med AB, Uppsala, Sweden) is a combination of dextranomer (cross-linked polysaccharides) and hyaluronic acid. Dextranomer has been used in wound treatment for several years. Nonanimal stabilized hyaluronic acid is similar to natural hyaluronic acid found in the body. The material is prepared in 0.7-mL syringes and used transurethrally with an implantation device (Implacer) and the injection of four syringes of material (see Fig 18-3). The material is in current use in the United States for ureterovesical reflux and is marketed as Deflux.


image

Figure 18-3 Implantation device. A. Implacer device with syringes in position before urethral insertion. B. Device activated and needles ready to be advanced into submucosal site.


(Courtesy of Q-med AB, Seminariegatan 21, SE-752 28 Uppsala, Sweden.)


Permacol (Tissue Science Laboratories plc [TSL], Aldershot, Hampshire, UK) is approved for use in Europe and is currently under study protocol in the Unites States. Permacol is a sterile injectable suspension of acellular cross-linked porcine collagen matrix.



TECHNIQUES

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Mar 11, 2016 | Posted by in Reconstructive surgery | Comments Off on Urethral Injection of Bulking Agents for Intrinsic Sphincter Deficiency

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