Skip to main content

Bulkamid — Polyacrylamide Hydrogel (PAHG)

Bulkamid (Contura International A/S, Søborg, Denmark) is a nonbiodegradable, particle-free polyacrylamide hydrogel (PAHG) urethral bulking agent for female stress urinary incontinence (SUI) and stress-predominant mixed incontinence. FDA-approved in 2020; CE-marked in Europe since ~2006.[2][3]

Composition & Material Properties​

  • 2.5% cross-linked polyacrylamide in 97.5% sterile water — a homogeneous, transparent hydrogel without particles (distinguishing it from Macroplastique silicone microparticles and Coaptite calcium hydroxyapatite).[1][2]
  • Nonbiodegradable — permanent volume augmentation at the injection site.
  • No particle migration — homogeneous gel eliminates risk of embolization or distant migration.
  • No erosions reported with PAHG across multiple studies — a notable departure from other bulking agents.[3]
  • Integrates with surrounding tissue through collagen infiltration; no granuloma formation.[1]

Mechanism​

Submucosal hydrogel deposits increase urethral coaptation, improving the seal during rises in abdominal pressure. Over time, host collagen infiltrates the hydrogel matrix, providing stable, long-term volume augmentation.[1][4]

Injection Technique​

Transurethral under direct endoscopic visualization using the dedicated Bulkamid system:[1][5]

  • Anesthesia: local (periurethral lidocaine ~10 mL); sedation or GA optional.
  • Setting: office or outpatient — no OR required.
  • Site: submucosal injections ~1.5 cm distal to the vesicourethral junction at the 10, 2, 5, 7 o'clock positions (typically 2–4 sites).
  • Volume: ~0.5–1.0 mL per site; total titrated to visible coaptation.
  • Sessions: up to 3 sessions at 1-month intervals as initial protocol; a top-up at 3 months is offered for persistent symptoms.[2][5]
  • Duration: ~10–15 minutes; same-day discharge after a successful void / acceptable PVR.

Patient Selection​

Best candidates[3][6]

  • Wish to avoid more invasive surgical management (MUS).
  • Elderly or medically comorbid; poor surgical candidates.
  • Intrinsic sphincter deficiency (ISD).
  • Recurrent / persistent SUI after failed midurethral sling.
  • Younger women who have not completed childbearing.
  • Jurisdictions where mesh slings have been suspended (UK, Ireland, Australia).

Predictors of optimal response

  • Age ≥ 60 with < 2.5 daily SUI episodes — 90% treatment effect, 38% cured (vs 13% cure in younger patients with ≥ 2.5 daily episodes).[7]
  • Normomobile urethra (linear dorsocaudal movement 6–24 mm on sonography) — greatest continence-score improvement.[8]

Clinical Efficacy​

Pivotal RCT (Bulkamid vs Contigen collagen)​

FDA-registration trial, single-blind, 33-center, n = 345. At 12 months:[2]

  • ≥ 50% leakage reduction: 53.2% (PAHG) vs 55.4% (collagen)
  • Zero SUI episodes: 47.2% vs 50%
  • Self-reported cured / improved: 77.1% vs 70%
  • Noninferior to Contigen (which is no longer marketed).

Short- and Medium-Term Outcomes​

StudynFollow-upOutcome
Lose 2010 (open multicenter)13512 mo66% subjective responder; SUI episodes 3.0 → 0.7/d; 35% reinjection.[9]
Toozs-Hobson 201213524 mo64% subjective responder, maintained from 67% at 12 mo.[10]
Lamblin 2025 (French multicenter retrospective)32024 mo63.7% cured, 21.9% improved; low complication rate.[11]
Sze 2026 (retrospective)2846.7 mo medianUDI-6 45.8 → 16.7; 16.5% reinjected; 6.0% progressed to sling.[12]

Systematic review (8 studies, n = 767): 24.3% required reinjection; subjective success 66–89.7% at 12 mo; objective success 25.4–73.3%.[4][13]

Long-Term Outcomes — Helsinki TVT vs PAHG RCT​

The landmark TVT vs PAHG randomized trial (Helsinki University Hospital, n = 223) — 5-year follow-up with 92% retention, published in NEJM Evidence 2025:[5]

  • PAHG did not meet noninferiority vs TVT for patient satisfaction (VAS ≥ 80: 74.7% PAHG vs 92.7% TVT).
  • Median satisfaction nonetheless high in both arms (PAHG 90, TVT 98).
  • Complications twice as common with TVT (43.8% vs 22.2%); reoperations mainly TVT-side.
  • 86% of PAHG patients still considered themselves cured or improved at 5 years (92% at 1 yr, 89% at 3 yr).
  • Objective cure (negative cough stress + pad test): 47% at 5 yr (vs 54% at 1 yr, 50% at 3 yr).

Beyond 5 yr: retrospective data show 67% subjective cure/improvement at 7 yr (primary procedure) and 53% success at 7–8 yr. AUA/SUFU 2023 notes PAHG has the longest persistence of effect among bulking agents — 96 months.[3][5]

Bulkamid vs Midurethral Sling​

ParameterBulkamidTVT
Subjective cure/improvement (5 yr)86%95%[5]
Objective cure (5 yr)47%~96%[5][14]
Patient satisfaction VAS ≥ 80 (5 yr)74.7%92.7%[5]
Any complication (5 yr)22.2%43.8%[5]
ReoperationRare4.1%[3]
Re-treatment rate (2 yr)27.0%0.9%[15]
AnesthesiaLocal (office)Local or GA
Mesh erosion riskNone1–3.7%

Finnish real-world cohort (n = 391): when offered both, 55% chose TVT, 45% chose PAHG. PAHG had higher re-treatment but Clavien-Dindo I–II only complications (vs I–IIIb for TVT).[15]

Cost-effectiveness. When > 58% of PAHG procedures are office-based, PAHG is cost-effective. MUS leads on effectiveness (1.86 QALYs) but only marginally over PAHG (1.82 QALYs), below the minimally important difference.[16]

After Failed Midurethral Sling​

Meta-analysis of 11 studies: pooled 80% (95% CI 74–85%) cure/improvement specifically for Bulkamid after failed MUS.[17]

Norwegian registry (n = 57 after failed TVT):[18]

  • 72.9% negative stress test postop
  • 73.7% satisfied with treatment
  • 1 complication in 67 injections (1.5%)
  • Among patients with preop UUI: 39.5% cured, 36.8% improved
  • De novo urgency: 8.8% overall (26.3% among those without preop urgency)

Safety Profile​

Across multiple series, no serious long-term adverse events:[2][4][5]

  • Transient hematuria: ~7.2%
  • Injection site pain / discomfort: 4–14%
  • UTI: 2.2–7%
  • Acute (transient) urinary retention: ~3.1%

Notable safety advantages over MUS: no bladder perforation risk, no mesh erosion, no chronic mesh pain, no voiding dysfunction requiring revision, Clavien-Dindo grade I–II only, and does not preclude future sling placement.[15]

Post-Prostatectomy SUI (Male)​

PAHG and other bulking agents have been used for post-prostatectomy SUI but are generally inferior to AUS or male sling for this indication.[19][20] Early injection after RP may improve early continence and QoL during recovery, but long-term durability is limited, particularly in severe incontinence.[21] AUS remains the gold standard for persistent post-prostatectomy SUI.[22][23]

Vesicoureteral Reflux (Pediatric)​

PAHG has been evaluated for endoscopic VUR treatment. Prospective series (n = 76 patients, 123 refluxing units):[24]

  • 71% success after a single injection (comparable to dextranomer/HA).
  • Median injected volume 1.0 mL per renal unit.
  • No upper-tract deterioration or bulking-agent calcifications at 36 months.

Guideline Endorsement​

The 2023 AUA/SUFU guideline on surgical treatment of female SUI notes a role for bulking agents in patients who wish to avoid more invasive surgery, prioritize shorter recovery, or have insufficient improvement after a prior anti-incontinence procedure. The guideline specifically highlights that PAHG has the longest persistence of effect (96 months) among bulking agents and that erosions were not noted with PAHG, unlike other agents. Inadequate data exist to formally recommend one injectable over another.[3]

Regulatory Status​

  • FDA-approved (2020) for female SUI.
  • CE-marked in Europe (~2006).
  • Available in >30 countries.
  • Not a mesh product — unaffected by FDA mesh restrictions or international mesh suspensions.

Advantages​

  • Minimally invasive, office-based procedure under local anesthesia.
  • No mesh, no erosion risk, no chronic mesh-related pain.
  • Excellent safety profile (Clavien-Dindo I–II only).
  • Does not preclude future surgical options.
  • Durable effect (86% cured/improved at 5 yr; documented to 96 mo).
  • Cost-effective when office-based.

Limitations​

  • Lower objective cure than MUS (~47% vs ~96% at 5 yr).[5]
  • Higher re-treatment rate (~16–27% within 2 yr).[12][15]
  • Did not meet noninferiority criteria vs TVT in the only head-to-head RCT.[5]
  • Limited long-term data beyond 5–8 yr.
  • Limited evidence in male SUI.
  • Younger patients and those with more severe SUI have lower cure rates.

See also: Macroplastique, Coaptite, Durasphere, Urethral Bulking Agents (procedure).

References​

1. Lukanović D, Blaganje M, Rhazi I, Deval B. Urethral Bulkamid® Injection After Failed Midurethral Sling: A Step-by-Step Video. International Urogynecology Journal. 2023;34(11):2843-2845. doi:10.1007/s00192-023-05608-z

2. Sokol ER, Karram MM, Dmochowski R. Efficacy and Safety of Polyacrylamide Hydrogel for the Treatment of Female Stress Incontinence: A Randomized, Prospective, Multicenter North American Study. The Journal of Urology. 2014;192(3):843-849. doi:10.1016/j.juro.2014.03.109

3. 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

4. Kasi AD, Pergialiotis V, Perrea DN, Khunda A, Doumouchtsis SK. Polyacrylamide Hydrogel (Bulkamid®) for Stress Urinary Incontinence in Women: A Systematic Review of the Literature. International Urogynecology Journal. 2016;27(3):367-375. doi:10.1007/s00192-015-2781-y

5. Itkonen Freitas AM, Isaksson C, Rahkola-Soisalo P, Mentula M, Mikkola TS. Tension-Free Vaginal Tape versus Polyacrylamide Hydrogel Injection for Stress Urinary Incontinence — 5-Year Follow-Up. NEJM Evidence. 2025;4(5):EVIDoa2400216. doi:10.1056/EVIDoa2400216

6. Gallo K, Weiner H, Mishra K. An Update on Surgical Management for Stress Urinary Incontinence. Current Opinion in Obstetrics & Gynecology. 2024;36(6):433-438. doi:10.1097/GCO.0000000000000989

7. Elmelund M, Sokol ER, Karram MM, Dmochowski R, Klarskov N. Patient Characteristics That May Influence the Effect of Urethral Injection Therapy for Female Stress Urinary Incontinence. The Journal of Urology. 2019;202(1):125-131. doi:10.1097/JU.0000000000000176

8. Nosal N, Gerling A, Kuhn A, et al. Predictive Measurement of Urethral Mobility for Successful Transurethral Bulkamid Application in Women With Stress Urinary Incontinence. Journal of Clinical Medicine. 2025;14(18):6555. doi:10.3390/jcm14186555

9. Lose G, Sørensen HC, Axelsen SM, et al. An Open Multicenter Study of Polyacrylamide Hydrogel (Bulkamid®) for Female Stress and Mixed Urinary Incontinence. International Urogynecology Journal. 2010;21(12):1471-1477. doi:10.1007/s00192-010-1214-1

10. Toozs-Hobson P, Al-Singary W, Fynes M, Tegerstedt G, Lose G. Two-Year Follow-Up of an Open-Label Multicenter Study of Polyacrylamide Hydrogel (Bulkamid®) for Female Stress and Stress-Predominant Mixed Incontinence. International Urogynecology Journal. 2012;23(10):1373-1378. doi:10.1007/s00192-012-1761-8

11. Lamblin G, Boix S, Moret S, et al. Effectiveness and Safety Profile of Urethral Bulking With Bulkamid® for Stress Urinary Incontinence: A French Multi-Center Cohort Study. International Urogynecology Journal. 2025;36(1):205-211. doi:10.1007/s00192-024-06005-w

12. Sze C, Advano D, Fernandez CM, et al. Symptom Relief and Practice Setting Variation in Bulkamid Injections for Stress Urinary Incontinence. Neurourology and Urodynamics. 2026. doi:10.1002/nau.70289

13. Siddiqui ZA, Abboudi H, Crawford R, Shah S. Intraurethral Bulking Agents for the Management of Female Stress Urinary Incontinence: A Systematic Review. International Urogynecology Journal. 2017;28(9):1275-1284. doi:10.1007/s00192-017-3278-7

14. Itkonen Freitas AM, Isaksson C, Rahkola-Soisalo P, et al. Tension-Free Vaginal Tape and Polyacrylamide Hydrogel Injection for Primary Stress Urinary Incontinence: 3-Year Followup From a Randomized Clinical Trial. The Journal of Urology. 2022;208(3):658-667. doi:10.1097/JU.0000000000002720

15. Särkilahti L, Isaksson C, Mikkola TS. Tension-Free Vaginal Tape Versus Polyacrylamide Hydrogel Bulking Agent for Stress Urinary Incontinence: Patient Choice and Outcomes in Finland. International Urogynecology Journal. 2025;36(4):895-902. doi:10.1007/s00192-025-06119-9

16. Chang OH, Shepherd JP, Cadish LA, et al. Urethral Bulking With Polyacrylamide Hydrogel Compared With Other Treatments for Stress Urinary Incontinence: A Cost-Effectiveness Analysis. Obstetrics and Gynecology. 2024;143(3):428-430. doi:10.1097/AOG.0000000000005503

17. Braga A, Caccia G, Papadia A, et al. Urethral Bulking Agents for the Treatment of Recurrent Stress Urinary Incontinence: A Systematic Review and Meta-Analysis. Maturitas. 2022;163:28-37. doi:10.1016/j.maturitas.2022.05.007

18. Myhr SS, Rakovan M, Schiøtz HA. Periurethral Injection With Polyacrylamide After Previous TVT Surgery. International Urogynecology Journal. 2022;33(4):1017-1022. doi:10.1007/s00192-021-04891-y

19. Radadia KD, Farber NJ, Shinder B, et al. Management of Postradical Prostatectomy Urinary Incontinence: A Review. Urology. 2018;113:13-19. doi:10.1016/j.urology.2017.09.025

20. Bauer RM, Bastian PJ, Gozzi C, Stief CG. Postprostatectomy Incontinence: All About Diagnosis and Management. European Urology. 2009;55(2):322-333. doi:10.1016/j.eururo.2008.10.029

21. Schneider T, Sperling H, Rossi R, Schmidt S, Rübben H. Do Early Injections of Bulking Agents Following Radical Prostatectomy Improve Early Continence? World Journal of Urology. 2005;23(5):338-342. doi:10.1007/s00345-005-0010-x

22. Bauer RM, Gozzi C, Hübner W, et al. Contemporary Management of Postprostatectomy Incontinence. European Urology. 2011;59(6):985-996. doi:10.1016/j.eururo.2011.03.020

23. Sandhu JS. Treatment Options for Male Stress Urinary Incontinence. Nature Reviews Urology. 2010;7(4):222-228. doi:10.1038/nrurol.2010.26

24. Ramsay S, Blais AS, Morin F, et al. Polyacrylamide Hydrogel as a Bulking Agent for the Endoscopic Treatment of Vesicoureteral Reflux: Long-Term Results and Safety. The Journal of Urology. 2017;197(3 Pt 2):963-967. doi:10.1016/j.juro.2016.08.093