There have been many RCT’s on the efficacy of surgical treatment for female stress urinary incontinence (SUI), concluding that mid-urethral slings (MUS) are currently the gold standard for surgical treatment. However, MUS surgery is not always a viable option. Mesh-surgery related policy, the wish to conceive a child, dysfunctional voiding, or serious comorbidities may preclude invasive surgery. In these circumstances, injection of a urethral bulking agent can be applied instead [1]. Recently, an RCT comparing the urethral bulking agent polyacrylamide hydrogel (PAHG) with the tension-free vaginal tape (TVT) suggested that, even though bulking agents are less effective, they serve as a safe and durable treatment option for females with SUI [2]. Currently, PAHG is mostly offered to women as a salvage or secondary treatment after MUS failure. PAHG can also be used as primary second-line therapy for patients with SUI or stress-predominant mixed urinary incontinence (MUI), when MUS surgery is not an option [3]. The aim of our study was to assess the outcome of PAHG urethral injections as a treatment for women with SUI, who are not eligible for treatment with MUS.

We performed a single-arm, patient cohort study of patients with SUI or stress-predominant MUI who were treated with PAHG between 2009 and 2020. All patients received a consent form and questionnaire in April 2020, and patient data was retrospectively collected from their records. Primary outcome was the subjective improvement rate, defined as an answer “(very) much better” on the Patient Global Impression of Improvement (PGII). Secondary outcomes were: subjective cure rate (a negative answer to the Urogenital Distress Inventory (UDI) stress subscale question 4), patient satisfaction (Visual Analogue Scale of ≥ 8.0), and to what extent patients would recommend PAHG treatment. Further, we evaluated complication rate, the amount of PAHG injected and the number of reinjections.

A total of 357 women with pure SUI or stress-predominant MUI were included, of which 153 (42.9%) completed and returned the questionnaire. These women perceived a subjective improvement rate of 52.1%. The subjective cure rate was 30.9%. A satisfaction score of ≥ 8.0 was achieved in 48.6% of the patient group. Minor adverse events due to the procedure were reported in 21% of patients. No serious adverse events were noted. On average patients were injected with 1.4 mL of PAHG. 134 women (37.5%) needed reinjections. 78.5% of patients would recommend PAHG treatment to others.

Our large cohort of patients showed that half of the women experienced an improvement of their SUI after PAHG urethral injections as recourse treatment. MUS surgery has shown a subjective improvement rate around 75%, but our study investigated a specific population of patients unfit to receive MUS and showed that these patients can still be treated for their SUI. Many showed benefits from treatment with PAHG injections. A persistent high satisfaction rate after mid- to long-term follow-up was found and the PAHG urethral injections were a safe procedure with only minor adverse events. Furthermore, this is one of the few studies that evaluate the subjective success, safety and patient satisfaction of urethral injection therapy with PAHG over a longer period of time.

Our study demonstrates that PAHG is a valuable asset in the treatment of female SUI, especially for patients unfit to receive MUS.

Altman D, Ghilotti F, Bellocco R, Zetterstrom J, Kopp Kallner H. Transurethral Polyacrylamide Hydrogel Injection Therapy in Women Not Eligible for Midurethral Sling Surgery. Female Pelvic Med Reconstr Surg. 2017;23(5):318-323.
Itkonen Freitas AM, Isaksson C, Rahkola-Soisalo P, Tulokas S, Mentula M, Mikkola TS. Tension-Free Vaginal Tape and Polyacrylamide Hydrogel Injection for Primary Stress Urinary Incontinence: 3-Year Followup from a Randomized Clinical Trial. J Urol. 2022;208(3):658-667.
Hussain SM, Bray R. Urethral bulking agents for female stress urinary incontinence. Neurourology and Urodynamics. 2019;38(3):887-892.