I have always been fond of the midurethral sling (MUS). I trained at a time where I was fortunate enough to have been taught multiple traditional procedures (autologous fascial pubovaginal sling [AFPVS], open Burch colposuspension). When MUS was launched in the middle of my residency, I rejoiced that we had a minimally invasive procedure to treat female stress urinary incontinence (SUI). For years, my algorithm for managing SUI included initial conservative management (behavioral, lifestyle, dietary), pelvic floor muscle therapy and lastly, MUS (or AFPVS/Burch in select patients) in women desiring surgical correction.

I had some experience with urethral bulking agents (UBAs) but was never impressed with the outcomes, nor did I routinely offer them. I reserved UBAs for salvage procedures, in women who wished to continue conceiving and those who were too old or sick to take to the operating room. In 2017, the AUA/Society of Urodynamics, Female Pelvic Medicine and Urogenital Reconstruction (SUFU) published guidelines on treatment of the “index patient” with SUI (healthy female considering surgery, no previous SUI surgery) and concluded that physicians may offer MUS, AFPVS, colposuspension and UBAs, but while UBAs “are viable treatments for SUI; little long-term data exist for them. Re-treatment tends to be the norm for bulking agent therapy, and there are inadequate data to allow the recommendation of one injectable agent over another,” underscoring the general sentiment that, in most cases, choosing a UBA is just putting off the inevitable need for surgery.¹

Prior to the U.S. Food and Drug Administration public health notification (2008) and safety communication (2011), MUS was the most popular surgical treatment for female SUI in the United States. Between 2000 and 2009, more than 182,000 procedures for SUI were performed, the majority of which were slings (see table).² Subsequently, patient and surgeon concern over mesh complications began to take its toll and mesh usage for SUI declined as much as 43% (fig. 1).³ This turn of events accentuated the already difficult problem of encouraging women to seek definitive care. Stress incontinence remains underdiagnosed and undertreated with only 25% of affected women seeking care, and of those, less than half receiving treatment.⁴ The most commonly reported reasons for avoiding care are embarrassment, being too busy and viewing surgery or medication as an unacceptable treatment option.⁵

Figure 1. Trends of surgeries for stress urinary incontinence.

The challenge for us as providers is to motivate women to accept treatment for SUI in this risk averse climate. Multiple studies have highlighted that, above all, women want options–and perceived safety is paramount. A recent meta-analysis comparing UBAs to other surgical interventions found a lower rate of complications following UBA injection.⁶ Compared with alternative surgical treatments, UBAs may be preferable for patients wishing to avoid risk, not take off significant time from work, exercise, or sexual activity, or for those in whom advanced age or medical comorbidities make undergoing anesthesia a larger risk. While UBAs may not be on par with MUS in the ability to eradicate SUI they may not need to be for women to choose them. Patients who wish to avoid the use of a synthetic mesh or a more invasive surgical intervention may prefer UBA injection, even in the setting of the need for repeat injections. Although traditionally UBAs have been reserved for patients with a diagnosis of intrinsic sphincter deficiency (ISD), a weakened urethral closure mechanism as defined by the International Continence Society (ICS), numerous studies have shown clinical utility in using injectable agents in the setting of urethral hypermobility as well.⁷ Furthermore, AUA guidelines suggest there is little benefit to performing preoperative urodynamic testing in the initial evaluation of SUI, rendering the diagnosis of ISD indeterminable in the majority of cases.¹

Although there have been numerous UBAs employed over the years, currently 2 classes have emerged. The first type is a particulate suspended in a carrier gel which dissolves over time. The second type is nonparticulate, a homogenous hydrogel (PAHG) which forms “cushions” in the submucosal layer proximal to the bladder neck (fig. 2). PAHG is injected through a proprietary cystoscope accompanied by a rotatable sheath which facilitates injection in a standardized technique. Because there is no carrier gel to dissolve, the cushions persist in the urethral tissues over time. It can be performed in an ambulatory setting with local anesthesia or under sedation according to patient and surgeon preference. A recently published randomized controlled trial comparing PAHG to MUS confirmed an 80% satisfaction rate and, with the exception of de novo urgency, a 0% adverse event rate in the PAHG arm at 1 year.⁸ The agent has impressive longevity with published 7-year data demonstrating strong patient satisfaction rates and 80% of patients not seeking further treatment for their SUI.⁹

Figure 2. A, pre-PAHG. B, first injection. C, post-PAHG.

In the current age of care pathways we must view the management of SUI through our patients’ eyes. As surgeons we are trained to fix problems–but so much more is involved in patients’ decision making than the success rate of the procedure. In the “Voice Your Choice” study conducted with the goal of understanding the most important factors women consider when choosing one procedure over another, UBAs were the preferred first option 64% of the time. In addition, many women desired a hierarchical treatment pathway starting with the least invasive (lowest perceived risk) and ending with most invasive (highest perceived risk) if the least invasive procedure failed.¹⁰ The fact remains that a good percentage of women will never feel comfortable with an invasive procedure regardless of degree of bother if the perceived risk is high enough.

Since I began changing my algorithm in early 2020 to offer UBAs–specifically PAHG–in the initial treatment of SUI before MUS, I have been amazed by the volume of patients who gratefully consent. UBAs have the unique position of being successful enough and risk-friendly enough to make them a first choice for women. So now we need to ask why they shouldn’t be a first choice for doctors.