Polydimethylsiloxane Erosion as a Cause for Recurrent Urinary Tract Infections

Abstract

Background: Urethral bulking agents are commonly used for the management of stress urinary incontinence (SUI). Little long-term data exist for these agents, with few reports of migration or urethral erosion.

Case Presentation: We describe a unique case of a woman who received a midurethral sling 3 years after receiving an injection of the urethral bulking agent, polydimethylsiloxane, because of persistent SUI. Her subsequent recurrent urinary tract infections led to the identification of a bladder neck erosion of the urethral bulking agent with a concomitant calcification.

Conclusion: When irritative voiding symptoms are experienced in patients who have received urethral bulking agents, erosion must be considered. Furthermore, little is known regarding the definitive management of SUI in patients that have previously received an injection of a urethral bulking agent.

Introduction

Polydimethylsiloxane (Macroplastique^®) is a commonly used urethral bulking agent with few cases of urethral erosion and agent migration reported. We describe a case of bladder neck erosion and subsequent calcification leading to recurrent urinary tract infections (UTIs) and irritative voiding symptoms.

Presentation of the Case

Clinical history

A 28-year-old woman presented with a 9-year history of stress urinary incontinence (SUI) since having a vaginal delivery. Two years before presenting she had been seen by another urologist and treated with the urethral bulking agent, polydimethylsiloxane.

Physical examination and testing

At her current presentation, her physical examination included a positive supine stress test. She had no evidence of vaginal erosion of the urethral bulking agent. Urodynamics demonstrated a cough leak point pressure of 115 cm H₂O at 316 mL. Cystoscopy at that time showed the location of the prior urethral bulking injection at the 8 o'clock position of the bladder neck but no evidence of extrusion.

Initial intervention

After an unsuccessful trial of pelvic floor physical therapy, she underwent a retropubic midurethral sling with complete resolution of her stress incontinence. Starting ∼8 months postoperatively, she was diagnosed and treated for five UTIs in 7 months. Owing to her recurrent UTIs, she underwent office cystoscopy ∼15 months after her sling procedure, which revealed a calcified mass at her bladder neck.

Follow-up intervention

After this diagnosis, she was taken to the operating room for management of the calcified mass. Initially, holmium laser lithotripsy of the calcification at the bladder neck was performed at settings of 0.8 J and 8 W. After the lithotripsy of the calcified portion, a softer material consistent with the urethral bulking agent was identified. The bipolar resectoscope was then used to remove the bulking agent and to resect a portion of the bladder neck tissue. The bulking agent was then irrigated from the bladder and removed through the resectoscope. During this procedure, the midurethral sling was not encountered (Fig. 1).

FIG. 1.

(A) Calcification at bladder neck before intervention. (B) Bladder neck tissue with evidence of impregnated urethral bulking agent after removal of calcification. (C) Bladder neck tissue after resection.

A Foley catheter was then maintained for 2 days postoperatively. She was seen in the first month postoperatively with no return of UTIs, incontinence, or retention.

Discussion

Current AUA/SUFU guidelines for SUI describe surgical treatments for bothersome urinary incontinence. These treatments include midurethral sling, autologous fascial sling, Burch colposuspension, and injectable bulking agents. Little long-term data exist for urethral bulking agents.¹ Bulking agents are an option for patients found to have a fixed immobile urethra (“Intrinsic Sphincter Deficiency”).¹ Aside from this indication, it is suggested that the role for bulking agents may be considered in patients with comorbidities, high anesthetic risk, and those who prefer a less invasive approach.² In comparison with other surgical treatment options for SUI, injection of urethral bulking agents have a significantly higher recurrence rate.² With a higher recurrence rate and a need for repeat procedures, it is uncommon for this to be a first-line treatment option in a young healthy patient as seen in the patient described in this report.

The field of injectable biomaterials has been dynamic with the quest for identifying an ideal injectable material ongoing. Davis et al. defined an ideal urethral bulking agent as a biomaterial that remains biocompatible, durable, and nonimmunogenic.³ Currently, calcium hydroxylapatite (Coaptite^®), carbon beads (Durasphere^®), and polydimethylsiloxane macroparticles suspended within a hydrogel (Macroplastique) are commonly used.

de Vries et al. conducted an extensive literature review that included 14 published articles and 3 case reports involving polydimethylsiloxane.⁴ In 14 original articles that involved 654 patients, there were 7 reports of urethral/vaginal erosion and no reports of agent migration.⁴ In the three case reports involving four patients that were reviewed, there was one case of migration and no cases of urethral erosion.⁴ Before this, a 2013 systematic review of polymethylsiloxane articles, which included 958 patients, reported adverse events of urinary retention, urge incontinence, UTI, temporary dysuria, and transient hematuria.⁵ According to the published literature, rates of vaginal or urethral erosion is quite low with this material.

Conclusion

Persistent stress incontinence after polydimethylsiloxane injection is consistent with its lower success rate. Although this patient was treated with a midurethral sling, recurrent UTIs were the trigger for further investigation. Erosion of polydimethylsiloxane into the lumen of the bladder appeared to be the cause. There is a possibility that placement of the midurethral sling contributed to the migration of the bulking agent. Currently, there are no guidelines regarding the management or removal of injectable bulking agents before definitive stress incontinence surgery. Often injectable therapy is used in the setting when prior surgical treatments have failed or the patient is not a candidate for more invasive interventions. In patients with irritative voiding symptoms and recurrent UTIs after urethral bulking agent and/or surgical treatment of SUI, investigation for a foreign body in the urinary tract appears prudent.

Abbreviations Used

SUI

stress urinary incontinence

UTI

urinary tract infection

Disclosure Statement

No competing financial interests exist.

Cite this article as: Raffee S, Atiemo H (2019) Polydimethylsiloxane erosion as a cause for recurrent urinary tract infections, Journal of Endourology Case Reports 5:3, 117–119, DOI: 10.1089/cren.2019.0007.