Urethral bulking agents for SUI: Rethinking their indications
Rising interest in alternatives to sling procedures and increasing evidence of successful outcomes for urethral bulking agents make them a potential primary treatment option for patients with SUI
Stress urinary incontinence (SUI) is the involuntary loss of urine with increased intra-abdominal pressure, such as with physical exertion, sneezing, or coughing.1 Currently, the gold standard treatment for SUI is surgical repair with the use of a synthetic midurethral sling (MUS), based on long-term data that support its excellent efficacy and durability. The risk-benefit balance of MUS continues to be scrutinized, however, with erosions and pain poorly studied and apparently underreported.
The medical-legal risks associated with the MUS are a significant concern and have led many patients to reconsider this option for their condition. Many other countries (United Kingdom, Australia, New Zealand, and European Union) are now re-evaluating the use of the MUS.2 In the United Kingdom, for example, the National Institute for Health and Care Excellence (NICE) Guideline advises considering the MUS only when another surgical intervention is not suitable for the patient.3
In light of the heightened skepticism surrounding the MUS, interest has increased in the use of urethral bulking agents. These agents consist of a material injected into the wall of the urethra to improve urethral coaptation in women with SUI.4
A brief history of bulking agents
In 1938, Murless first reported the injection of sodium morrhuate for the management of urinary incontinence.4 Other early bulking agents introduced in the 1950s and 1960s included paraffin wax and sclerosing agents. Subsequently, Teflon, collagen, and autologous fat, among other agents, were found to be efficacious for augmenting urethral coaptation; however, only collagen initially demonstrated acceptable safety.5
Contigen (bovine dermal collagen cross-linked with gluteraldehyde) was approved as a bulking agent by the US Food and Drug Administration (FDA) in 1993; however, the manufacturing of bovine collagen was halted in 2011. Contigen was the only nonpermanent biodegradable urethral bulking agent, and its use required skin testing prior to use, as 2% to 5% of women experienced allergic reaction.4
Presently, 3 particle-based urethral bulking agents are FDA approved for marketing in the United States: Macroplastique (Laborie Medical Technologies), Coaptite (Boston Scientific), and Durasphere (Coloplast). In addition, Bulkamid (Contura), which was approved earlier this year, is a nonparticulate agent composed of a nonresorbable polyacrylamide hydrogel.5
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