In 1972, an artificial urinary sphincter (AUS) was developed for severe cases of stress urinary incontinence (1). Since 1983, the AMS800TM, manufactured by the American Medical System (Minnesota, US), has been used for AUS implantation (2). In Japan, the AUS has been available since 2012. In this study, we investigated the changes in the number of pads used over time and the results of long-term device use in patients who underwent AUS implantation at our hospital.

We included patients who underwent AUS implantation for stress urinary incontinence, between January 1, 2012 and March 31, 2024. We extracted the following items from the patients’ medical records: age, sex, causes of stress urinary incontinence, comorbidities, date of surgery, date of last follow-up, preoperative video-urodynamics, number of pads before and after surgery, and rate of non-revision of AUS devices. We investigated the risk factors for the replacement of the AUS device.

In total 92 cases were included in the study. The number of preoperative pads was 6.2 ± 3.0. The mean number of pads/day after surgery was 0.5 ± 0.6 at 1 year, 0.6 ± 1.0 at 2 years, 0.9 ± 1.2 at 3 years, 0.8 ± 1.3 at 4 years, 0.7 ± 1.5 at 5 years, 0.4 ± 0.6 at 6 years, 0.4 ± 0.5 at 7 years, 0.3 ± 0.5 at 8 years, 0.3 ± 0.5 at 9 years, and 0.3 ± 0.5 at 10 years (Figure 1A). The continence rates, defined as maintaining continence with one pad per day or less, were 94.2% at 1 year, 87.3% at 2 years, 76.6% at 3 years, 79.4% at 4 years, 88.0% at 5 years, 94.7% at 6 years, and 100% at 6–10 years (Figure 1B). The revision-free rates of the AUS equipment were 86.3% at 1 year, 83.1% at 2 years, 77.3% at 3 years, 72.5% at 4 years, 63.8% at 5 years, 63.8% at 6 years, and 53.5% at 7–10 years (Figure 1C). After AUS implantation, the device was removed in 11 cases (12.0%), reimplanted 6 case (6.5%), and replaced in 10 cases (10.9%). The position of the control pump was adjusted in 5 cases (5.4%). In the 10 patients who underwent AUS replacement, the median number of days from initial implantation to replacement was 1267.5 (983.5–1642.3 IQR). The urethral size at the time of initial implantation and at the time of replacement was 4 cm (4–4 IQR) and 3.5 cm (3.5–3.5 IQR), respectively (Figure 2A). In addition, the analysis of the factors affecting AUS replacement surgery revealed significant differences in multivariate factors of urethral stricture and detrusor overactivity (Figure 2B).

Urinary continence was maintained after the AUS pump was activated; however, the rate of urinary continence decreased approximately 3 years after the operation. This coincides with the timing of the AUS replacement surgery. In cases where the AUS was replaced, the urethral diameter was smaller at the time of replacement than at the time of initial implantation, possibly because of size mismatch with the cuff due to urethral atrophy. Based on the results of multivariate analysis, it is necessary to consider that patients with urethral stricture and detrusor overactivity may be at an increased risk for future replacement surgery. Most of the urethral strictures in this study were vesicourethral anastomotic strictures after radical prostatectomy. This suggests that vesicourethral anastomotic stricture may lead to urethral atrophy.

Although urinary continence was maintained to some extent, some patients required device revision. The urethral diameter was reduced in cases requiring AUS replacement. AUS replacement should be considered in patients with preoperative urethral stricture or detrusor overactivity.

J Urol. 167: 1125-1129, 1974
Eur Urol. 63: 681-689, 2013