Polyacrylamide hydrogel (PAHG, Bulkamid®) is one of several injectable agents currently used for the treatment of women with urinary stress incontinence (SUI). The aim of this study was to evaluate the preoperative clinical characteristics of women with SUI and mixed urinary incontinence with predominant stress form, underwent to transurethral injection of Bulkamid and persistent incontinence after the procedure.

This was a single-center prospective study. The local ethics committee approved the study and all patients signed an informed consent document. We included women who underwent transurethral injection of Bulkamid , on bladder neck, for SUI and mixed urinary incontinence with predominant stress form. We excluded women with pelvic organ prolapse or with a history of anti incontinence surgery. The preoperative evaluation included a medical history, a clinical examination, urodynamic study  and a dynamic translabial ultrasound. SUI was defined according to ICS standards and classified according to the Ingelman-Sundberg scale. Follow-up visit included a medical history, physical examination, and uroflowmetry with PVR measurement. A dynamic translabial ultrasound was performed 6 months post-surgery and again at the last visit. The objective cure for SUI was defined as the absence of urine leakage during the stress test. To determine the statistical significance of categorical data comparisons, we performed the Chi-squared test with a continuity correction for each 2 × 2 contingency table.Fisher’s exact test was used when expected frequencies were insufficient for a Chisquared test. We considered p < 0.05 to be statistically significant.

From June 2020 to June 2021, a total of 30 consecutive patients underwent transurethral injection of Bulkamid for SUI and mixed urinary incontinence with predominant stress form were included. Age mean 56.2±2.3 years.The objective cure rate was 80 % after 1 month and 66.6% within 6 months after the procedure.Table 1 showed the baseline characteristics of the population by dividing them into incontinent and continent patients at last visit. Incontinent women within 6 months have most of their bladder neck open (80%) and shorter urethra by preoperative translabial ultrasound compared to continent patients.Women with peristent stress incontinence  had severe preoperative incontinence (grade III) and mostly (70%) mixed urinary incontinence.

The failure of the bulking agent is a multifactorial phenomenon. The closure of the open bladder neck with the bulking agent could be one of the factors that guarantees post-operative continence.The reason why women with open baldder neck are more prone to treatment failure is not clear. Our technique involves making 4 wheals at the level of the bladder neck. An open neck is probably related to a more severe degree of incontinence.Infact, most of the patients, in this study,have stress incontinence grade III
However Kirchin showed that there are no-significant advantage in terms of patient satisfaction after mid-urethral injection in comparison to bladder neck injection but with no demonstrable difference in continence levels.
Also a short urethra could compromise the success of the procedure by creating technical problems. It may be difficult to perform wheals in a short urethra.Mixed incontinence may not benefit from bulking agent treatment due to the different pathophysiological mechanism.

A short urethra and the presence of severe  stress incontinence can compromise the results of the transurethral injection of Bulkamid. Patient selection is the key element to the success of this procedure