Imaging findings of vinyl dimethyl polydimethylsiloxane used as a paraurethral injectable for female stress urinary incontinence

Objectives: Vinyl dimethyl polydimethylsiloxane (VDPDMS) is a urethral bulking agent used for female stress urinary incontinence (SUI), that is clearly visible on computed tomography (CT). Clinical effects are promising, but it remains difficult to identify factors predicting clinical success. Clinical outcome might depend on the shape and position of the implants after injection. Objective of this study is to analyze the appearance and position of bulk material on CT scans and to see whether it is delivered the intended circumferential and mid-urethral position. Methods: A single-center retrospective study was performed in 20 women, treated with VDPDMS for SUI. A senior radiologist analyzed all CTs, using an assessment scheme. This scheme describes whether the bulk is scattered, mid-urethral, and/or circumferentially distributed. The imaging findings were subsequently correlated to the patient global impression of improvement (PGI-I) and the percentage of subjective improvement experienced 6 weeks post-operatively. Results: The patient’s mean age was 61 years, and they underwent median 2.0 previous surgical treatments for SUI. Three patients reported no improvement, 9 patients had 20–90% improvement and 8 reported >90% improvement of their SUI. In 17/74 (24%) positions, the implant was scattered rather than spherical. In 9/20 (45%), the implants were not located in the intended mid-urethral position. In 8/20 patients (40%), the material was distributed circumferentially. Conclusion: This is the first study describing the position and shape of VDPDMS in patients after treatment. The appearance and position of the implants appears to be variable, but optimal positioning or shape seems to be no absolute requisite for success.