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Urolastic — In-Situ Polymerizing Silicone Bulking Implant

Urolastic (PDMS-U) is a nonabsorbable silicone gel that polymerizes after periurethral injection to form a solid elastomeric implant.[1] It differs from Macroplastique, whose silicone macroparticles are formed before injection. Observational studies report improvement in stress urinary incontinence (SUI), but also retention, pain, exposure, erosion and excision of implanted material.[2][3]

Material and Mechanism​

The material is injected as a viscous liquid and cross-links within the periurethral tissue. The resulting mass adds bulk that augments urethral coaptation. Because it is a continuous mass rather than discrete particles, it was designed to conform to tissue contours and to limit particle migration. The material is nondegradable, but clinical series report exposure, erosion and material within the bladder.[1][3][4]

Injection Technique​

Published series describe periurethral injection under local anesthesia according to the manufacturer's instructions, without routine cystoscopy. The 2016 series reports initial injections at 10, 2, 4 and 8 o'clock with 0.5 to 1.25 mL per site[4]; the manufacturer's rev. 0 training manual instead describes initial deposits at 2, 5, 7 and 10 o'clock with 0.8 to 1.2 mL depending on site.[12] Check the instructions supplied with the device for clinical use.[4][12] Injection was performed by physicians certified in the technique.[5] Reinjection was needed in 16.7% to 35% of patients, with a pooled rate of 20% (95% CI 15% to 24%).[6] Confirm site, volume and technique against the current manufacturer's instructions for use.

Indications Studied​

Urolastic has been studied in women who are poor candidates for a midurethral sling (MUS). Kowalik and colleagues treated 20 such women, whose reasons were recurrent SUI, prior gynecologic oncologic surgery, neurologic disease with voiding problems, maximal flow below 15 mL/s, or a contraindication to general or regional anesthesia. Post-void residual above 150 mL was the most common adverse event (40%) but persisted in one patient, who preferred catheter management.[7] The manufacturer's rev. 0 training manual (PDF p. 9) lists neurogenic bladder, detrusor overactivity, acute urogenital inflammation, gross uterovaginal prolapse, overflow incontinence, pregnancy or the first postpartum year, urinary tract infection, active genital herpes, autoimmune disease or systemic corticosteroid treatment, and a midurethral sling within the preceding six months as contraindications.[12] Check current instructions supplied with the device.

Efficacy​

StudyDesign and populationFindings
Futyma 2015Uncontrolled multicenter study, 105 women, including 91 with recurrent SUIAt 12 months, 54/91 women with recurrent SUI (59.3%) were cured or improved on objective cough and 1-hour pad tests, while 45/91 (49.5%) were completely dry; 86/91 were available for follow-up. Among 14 women with primary SUI, 10/14 (71.4%) improved and 3/14 (21.4%) were completely dry.[8]
Kowalik 2018Prospective study, 20 women not optimal for MUS; 6 monthsSubjective improvement was 18/20 (90%); 10/18 women reporting improvement (56%) met the subjective cure threshold, and 13/20 (65%) had a negative cough stress test.[7]
Futyma 201666 women with recurrent SUI; 24 monthsAmong 49 of 66 women evaluated at 24 months, objective success was 16/49 (32.7%) and complete dryness was 22.4%; intention-to-treat estimates for all 66 were 24.2% and 16.7%, respectively.[4][6]
Capobianco 2018Systematic review of five studies; follow-up 6 to 24 monthsPooled objective success was 57% (95% CI 38% to 75%; I² = 82.3%), with a range of 32.7% to 67.0%. Subjective improvement exceeded 80% in two cohorts.[6]
Casteleijn 2020Cross-sectional study; 110 participants, 87 questionnaire respondents; median follow-up 25 monthsSatisfaction was 44/87 (51%) and subjective cure 40/87 (46%) among respondents; objective cure by cough stress test was 35/74 (47%) among those tested. Objective cure was less frequent in groups assessed longer after treatment.[2]

The Capobianco estimate is heterogeneous and short-term.

Comparison With Midurethral Sling​

A prospective two-arm cohort treated 131 women with Urolastic and 153 with MUS. At one year, subjective cure was 101/112 (90%) with MUS versus 40/87 (46%) with Urolastic (adjusted OR 4.9). Objective cure was 98/109 (90%) versus 58/92 (63%) (adjusted OR 5.4). Treatment was not randomized.[9]

Mean total cost was lower with Urolastic (€3,567 versus €6,688). At a willingness-to-pay of €25,000, MUS had an 84% chance of being cost-effective using the disease-specific quality-of-life measure, and Urolastic a 99% chance using EQ-5D-5L. The economic result therefore depended on the measure chosen.[9]

Safety and Removal​

Complication and reintervention rates are a central concern. In the nonrandomized 2023 two-arm cohort's 12-month analysis, vaginal exposure occurred in 31/131 Urolastic-treated women (23.6%), urethral erosion in 2/131, and implant excision in 26/131 (19.8%).[9]

  • 2020 cross-sectional cohort. Retention occurred in 22%, pain in 15% and dyspareunia in 15%. Exposure occurred in 7% and erosion in 5%. Reinjection was performed in 6% and excision of the bulk material in 18%. Overall, 66/110 (60%) had at least one postoperative complication and 36/110 (33%) underwent a reintervention; these categories can overlap. Most complications were mild and transient, but excision was indicated for severe or persistent pain, exposure or erosion.[2]
  • 2016 recurrent-SUI series. Complications occurred in 17/66 (25.8%). An oval-shaped mass of material was found inside the bladder in 3/66 (4.5%). The mechanism (migration, erosion or misplacement) was not established.[4]
  • 2021 systematic review. Erosion was reported with Macroplastique, Coaptite and Urolastic. The Urolastic cohort behind the quoted 24.6% figure counted exposure or erosion together: 17 events, or 27.4% of the 62 patients with complication follow-up in the 2018 Capobianco review.[10][6] No erosion or migration was reported with Bulkamid. The review found no direct comparisons of agents, so these figures come from different, largely noncomparative series.[10][6]

Learning Curve​

A secondary analysis of 203 procedures by nine physicians used predefined acceptable failure rates for overall complications, retention and excision. Five physicians performed at least 20 procedures. Two reached the competence threshold, one at procedure 20 and one at procedure 40. Procedure number was not significantly associated with complications. Technique varied between physicians, and retrospective underreporting is possible.[5]

Comparison With Other Bulking Agents​

FeatureUrolasticBulkamidMacroplastiqueCoaptite
MaterialIn-situ polymerizing silicone gelPolyacrylamide hydrogelSilicone macroparticlesCalcium hydroxylapatite
Erosion or exposure reported17/62 (27.4%) for combined exposure or erosion in one cohort[6]None reportedReportedReported
Migration or intravesical materialMaterial found inside the bladder in 3/66 (4.5%) in one series; mechanism not established[4]None reported——
Retention or elevated post-void residualUrinary retention 22% in the 2020 cohort[2]; post-void residual >150 mL in 40% of the 2018 cohort[7]——Temporary retention mean 34.2% in the 2021 review[10]

Source: Hoe 2021 and the Urolastic series above.[10][2][4][7]

Guideline Position​

It states that bulking agents are viable treatments, that retreatment is common, and that data are inadequate to recommend one injectable agent over another. The guideline cites longer-term data for calcium hydroxylapatite (73.2 months), polydimethylsiloxane (83 months), and polyacrylamide hydrogel (96 months).[11][13] The 83-month PDMS figure is the median follow-up of a Macroplastique series; its efficacy outcomes were reported at 60 months.[11][13] Erosion was not present with polyacrylamide hydrogel in the studies cited.[11] The 2024 AUGS clinical practice statement calls for counseling on risks, limited long-term efficacy data, repeat injections, possible surgery for recurrent SUI, implications for future procedures, and pelvic imaging findings after urethral bulking; this guidance applies to bulking agents as a class.[14]

Regulatory Status​

The manufacturer's distributor lists Urolastic in Europe.[3] Confirm CE certification, national authorization and current instructions for use before considering the product.

Prior Urolastic Implants​

In a patient with prior Urolastic, assess leakage, emptying, pain, hematuria, infection and exposure. Excision may be needed for severe or persistent pain, exposure or erosion.[2] In a 65-woman retrospective series, implants removed for anterior vaginal-wall erosion or postoperative pain were approached through a vaginal incision; two urethral erosions were removed cystoscopically.[15]

See also: Bulkamid, Macroplastique, Coaptite, and Urethral Bulking Agents — Procedure.

References​

1. Hussain SM, Bray R. Urethral Bulking Agents for Female Stress Urinary Incontinence. Neurourology and Urodynamics. 2019;38(3):887-892. doi:10.1002/nau.23924

2. Casteleijn FM, Kowalik CR, Berends C, et al. Patients' Satisfaction and Safety of Bulk Injection Therapy Urolastic for Treatment of Stress Urinary Incontinence: A Cross-Sectional Study. Neurourology and Urodynamics. 2020;39(6):1753-1763. doi:10.1002/nau.24417

3. NeoMedic GmbH. Urolastic product information. Distributor product page. Accessed September 12, 2026.

4. Futyma K, Nowakowski Ł, Gałczyński K, Miotła P, Rechberger T. Nonabsorbable Urethral Bulking Agent — Clinical Effectiveness and Late Complications Rates in the Treatment of Recurrent Stress Urinary Incontinence After 2 Years of Follow-Up. European Journal of Obstetrics, Gynecology, and Reproductive Biology. 2016;207:68-72. doi:10.1016/j.ejogrb.2016.10.011

5. Casteleijn F, Latul Y, van Eekelen R, Roovers JP. A Clinical Learning Curve Study of Polydimethylsiloxane Urolastic for Stress Urinary Incontinence: Does Safety Improve When Expertise Grow? Gynecologic and Obstetric Investigation. 2023;88(4):240-248. doi:10.1159/000530666

6. Capobianco G, Azzena A, Saderi L, et al. Urolastic®, a New Bulking Agent for Treatment of Stress Urinary Incontinence: A Systematic Review and Meta-Analysis. International Urogynecology Journal. 2018;29(9):1239-1247. doi:10.1007/s00192-018-3703-6

7. Kowalik CR, Casteleijn FM, van Eijndhoven HWF, Zwolsman SE, Roovers JWR. Results of an Innovative Bulking Agent in Patients With Stress Urinary Incontinence Who Are Not Optimal Candidates for Mid-Urethral Sling Surgery. Neurourology and Urodynamics. 2018;37(1):339-345. doi:10.1002/nau.23299

8. Futyma K, Miotła P, Gałczyński K, et al. An Open Multicenter Study of Clinical Efficacy and Safety of Urolastic, an Injectable Implant for the Treatment of Stress Urinary Incontinence: One-Year Observation. BioMed Research International. 2015;2015:851823. doi:10.1155/2015/851823

9. Casteleijn FM, de Vries AM, Tu LM, et al. Cost-Effectiveness of Urethral Bulking Polydimethylsiloxane-Urolastic® Compared With Mid-Urethral Sling Surgery for Stress Urinary Incontinence: A Two-Arm Cohort Study. BJOG. 2023;130(6):674-683. doi:10.1111/1471-0528.17396

10. Hoe V, Haller B, Yao HH, O'Connell HE. Urethral Bulking Agents for the Treatment of Stress Urinary Incontinence in Women: A Systematic Review. Neurourology and Urodynamics. 2021;40(6):1349-1388. doi:10.1002/nau.24696

11. Kobashi KC, Vasavada S, Bloschichak A, et al. Updates to Surgical Treatment of Female Stress Urinary Incontinence (SUI): AUA/SUFU Guideline (2023). The Journal of Urology. 2023;209(6):1091-1098. doi:10.1097/JU.0000000000003435

12. Urogyn BV. Urolastic Physician Training Manual. Rev. 0, pp. 16, 22–23. Manufacturer training manual.

13. Zullo MA, Plotti F, Bellati F, Muzii L, Angioli R, Benedetti Panici P. "Transurethral polydimethylsiloxane implantation: a valid option for the treatment of stress urinary incontinence due to intrinsic sphincter deficiency without urethral hypermobility." J Urol. 2005;173(3):898-902. doi:10.1097/01.ju.0000152568.40199.a8

14. Fleischmann N, Chughtai B, Plair A, et al. "Urethral Bulking." Urogynecology (Phila). 2024;30(8):667-682. doi:10.1097/SPV.0000000000001548

15. de Vries AM, van Breda HMK, Fernandes JG, Venema PL, Heesakkers JPFA. "Para-Urethral Injections with Urolastic for Treatment of Female Stress Urinary Incontinence: Subjective Improvement and Safety." Urol Int. 2017;99(1):91-97. doi:10.1159/000452450