According to international debates about the safety of use of synthetic sling for anti incontinence surgery, in many countries, alternative techniques are being used to avoid the complications typical of slings. An alternative technique that avoids surgical treatment is, the injection of urethral bulking agents. Several types of bulking agents are available for the treatment of stress urinary incontinence;t hese include Bulkamid (a polyacrylamide hydrogel), Macroplastique (crosslinked polydimethylsiloxane), Urolastic (a crosslinked polydimethylsiloxane) etc etc. The urethral bulking agents are rarely used as a primary treatment for stress urinary incontinence, infact the evidences to support these methods are few. In literature there is only one study that compares TVT with bulking agent in patients with primary stress urinary incontinence. Mikkola et all showed that mid urethral tension-free vaginal tape slings were associated with better satisfaction and cure rates than polyacrylamide hydrogel in women with primary stress urinary incontinence (SUI), with more  complications.
The aims of this study were to compare the outcomes, and the complications of TOT and transurethral bulking agent (BA) treatments in women with naive SUI

This was a randomized controlled trial comparing TOT and BA (Bulkamid®) for naive SUI. The study was approved by Ethics Committee and patients provided written informed consent. Inclusion criteria were: age over 18 years, SUI not responsive to conservative treatment, no previous incontinence surgery, without bladder obstruction. Exclusion criteria were:previous POP surgery; comorbidities such as diabetes or neurological disease; POP≥ stage II. Preoperative work out included: history; pelvic examination; urodynamic study, trans labial ultrasound. Patients completed self-administered UDI-6, IIQ7,FSFI. Patients were followed up at 1, 3, 6, and 12 months after surgery. At each visit, patients underwent clinical examination, evaluation of urinary and sexual symptoms, uroflowmetry with PVR measurement and PGI-I questionnaire. Furthermore patients completed UDI-6, IIQ-7, FSFI questionnaires. The complications was classified using both the ICS/IUGA and Clavien–Dindo classification.The allocation of this design was generated 
using StatsDirect, version 2.7.2, 2008 (StatsDirect, Altrincham, United Kingdom).A preliminary power analysis indicated that a sample size of 55 patients per group at  p < 0.05 would have 80% power to reject the null hypothesis that RASC and LASC 
are not equivalent. Power calculation was performed using PS: Power and Sample Size ver.3.0, 2009 (http://pspower-and-sample-size-calculation. software.informer.com/). The Mann-Whitney and Wilcoxon tests for unpaired and paired data, respectively, were used to compare ordinal and non-normally distributed  continuous variables. Categorical data were analyzed by the McNemar, chi-square or Fisher exact test. Two-tailed p <0.05 was considered significant. All calculations were 
performed with IBM® SPSS®, version 22.

55 women have been randomized to TOT and to 49 BA. The mean follow-up was 15±2.3 months. No significant inter-group differences emerged in the pre-operative evaluations of age (mean 53.2vs 50.22 for TOT and BA respectively, p=0.06) and BMI (mean 24.12 vs 25.47 kg/m2 for TOT and BA respectively, p=0.55).Table 1 showed a success rate after TOT of 96% and 85% after BA.The rate remained constant for one year of follow-up for TOT while it decreased significantly for BA after 6 months reaching 36% at one year.Fifteen of these patients underwent new bulking infiltration,16 chose a definitive implant with TOT. Only 2 grade III complication according to Clavien-Dindo classification has been reported in the TOT group (vaginal mesh exposure2AaT3S2). After one year, the difference in questionnaire scores between the two procedures was statistically significant (p=0.01), showing a worse impact on patients' quality of life and sexuality for BA

Our results demonstrate that both TOT and the bulking agent can be used in a naïve patient, but the results after one year are lower for the bulking agent. Probably it is due to the different mechanism of action and the material of the bulking agent.Further bioengineering or radiology studies could be useful to better interpret the different outcomes

Bulking agent is a procedure that can be used in naive patients, it has a greater safety profile but at 12 months the results are worse than the sling
Our results are part of counselling. Each patient can choose what type of surgery to do according to their expectations and ability to accept postoperative complications

Continence 12S (2024) 101352
DOI: 10.1016/j.cont.2024.101352