Durability of collagen injection for stress urinary incontinence in women proven by transvaginal 3-dimensional ultrasound

Objective: The aim of this study is to evaluate the durability of collagen injection (CI) using serial 3-dimensional (3D) transvaginal ultrasound (US) in women with sufficient improvement of stress urinary incontinence (SUI) symptoms not requiring additional treatment. Methods: After the institutional review board approval, a retrospective review of prospectively followed patients who underwent CI was conducted. Eligible patients received 3 or less consecutive CI for SUI with no reinjection afterward during the follow-up period and had a minimum follow-up of 1 year from the last CI. Serial 3D US was obtained for collagen volume and configuration at baseline (6-8 weeks postoperatively) and approximately every 12 months thereafter as clinically indicated. Results: Of 191 eligible patients from 1/99 to 6/11, 67 (35%) met the inclusion criteria. The mean age was 67 years (42-90 years) with mean follow-up from the time of last CI at 43 months (12-149 months). A total of 283 three-dimensional US were performed, with the mean of 4 (2-11) per patient. The mean number of injections was 1.4 (1-3) with a mean injected volume at 5.8 mL(2-18 mL). The volume retention rate compared with the baseline volume was 84% (12%-100%), with a decrease in mean collagen volumes between the baseline and last follow-up visit (3.2 vs 2.7 mL; P = 0.008). Collagen volume decreased by a mean of 0.11 mL for each year past the final injection (P = 0.0015) by mixed-effect model analysis. Conclusions: Although believed to be nondurable, CI was found to be objectively stable over time by transvaginal 3D US in a subset of women with durably improved SUI symptoms.