ZSI 375 artificial urinary sphincter for male urinary incontinence: a preliminary study


Frederic Staerman, Department of Urology, Polyclinique Les Bleuets, Groupe Courlancy, 24 rue Colonel Fabien, 51100 Reims, France. e-mail: urologie.staerman@orange.fr


Study Type – Therapy (case series)

Level of Evidence 4

What's known on the subject? and What does the study add?

Artifical Urinary Sphincter (AUS) is the treatment of choice for moderate to severe post-radical prostatectomy incontinence with good long-term outcomes despite risk of complications.

We report preliminary results of a new preconnected AUS (ZSI 375). Main change with the device currently available is the replacement of the abdominal reservoir by a pressure-regulated spring in the intrascrotal pump avoiding abdominal approach.


  • • To assess retrospectively the safety and efficacy of an artificial urinary sphincter, the ZSI 375 device (Zephyr Surgical Implants, Geneva, Switzerland), in male patients with moderate-to-severe stress urinary incontinence after a prostate or bladder intervention.


  • • The ZSI 375 device is a one-piece device consisting of an adjustable cuff, moulded to fit around the urethra, which is connected by a tube to a pump and a pressure-regulating tank. It has no abdominal reservoir.
  • • Patients underwent a perineal incision for cuff placement and an inguinal incision for pump and tank scrotal placement.
  • • Complications and pads used to manage incontinence were recorded.


  • • Between May 2009 and April 2011, 36 patients underwent ZSI 375 device placement. The median (range) follow-up was 15.4 (6–28) months.
  • • No patient experienced bladder overactivity, chronic urinary retention, or any other adverse effect after device activation. Complications leading to device removal arose in four patients (one case of erosion, three cases of infection).
  • • Social continence (0 or 1 pad/day) was achieved in 28/36 patients (78%) at 3 months and 26/36 patients (73%) at 6 months after device activation.
  • • In 12/14 patients for a sphincter closure pressure range of 60–70 cm H2O, in 3/3 patients for a range of 70–80 cm H2O and in 2/11 for a range of 90–100 cm, H2O social continence was achieved only after increasing the pressure of the cuff by trans-scrotal injection of saline.


  • • The ZSI 375 device is safe and effective but our follow-up may not have been long enough to identify all potential complications.
  • • Further research is needed to confirm these results and extend our investigation, for instance, to the peno-scrotal approach.

artificial urinary sphincter


radical prostatectomy


Since its introduction in 1973, the artificial urinary sphincter (AUS) has become the treatment of choice for male urinary incontinence [1,2]. Improvements in the device (double cuff) and new surgical approaches (transcorporeal and/or trans-scrotal) introduced in the 2000s have extended its use to the treatment for moderate-to-severe incontinence occuring after radical prostatectomy (RP) [3–5]; however, despite good long-term outcomes, AUS implantation remains a complex procedure with a risk of complications such as erosion, infection and mechanical failure. Revision rates attributable to mechanical failure range from 8 to 45% [6–8].

Surgeon experience is a key factor for success as the learning curve is long, but <10% of AUS implantations in the USA are performed by surgeons with experience of at least 100 procedures [9]. Most are carried out by occasional operators (1–3 procedures/year). As the number drops from >200 to five procedures, the risk of revision increases from 13 to 24% [10]. It could, no doubt, be reduced if the technique were simplified.

To facilitate AUS implantation, a new device, the ZSI 375 (Zephyr Surgical Implants, Geneva, Switzerland), with innovative features has been developed. It has no abdominal reservoir so as to reduce operating time and to avoid abdominal incision and dissection in scarred retroperitoneum, it is pre-connected, and it has a cuff that can be adjusted around the urethra. The aim of the present study was to analyse primarily the safety, but also the efficacy, of ZSI 375 in incontinent male patients.



We performed a retrospective analysis of consecutive patients who underwent ZSI 375 placement by two surgeons (C.G-L. and C.L.) between May 2009 and April 2011 for moderate-to-severe stress urinary incontinence after RP, TURP or bladder replacement. All had failed previous rehabilitation by pelvic floor training and electrostimulation. The preoperative evaluation included patient history, questions on pad use, a physical examination, cystoscopy, urine analysis and urodynamics to exclude an overactive bladder.


The ZSI 375 device works like a typical hydraulic AUS. It is a one-piece device made up of two parts connected by kink-resistant tubing. One part is an adjustable cuff moulded to fit around the urethra, the other is a pressure-regulating tank and pump that is placed in the scrotum (Fig. 1). The device has two circuits: a hydraulic circuit and a compensation pouch circuit, separated by a spring-regulated piston in the tank. It is supplied with a 5 mL syringe and two HUBER needles. Before use, the hydraulic circuit is first filled by injecting 4.5 mL saline via the cuff septum. The compensation pouch is then filled with 4.5 mL saline (Fig. 2), and, importantly, the device is deactivated (Fig. 3A).

Figure 1.

The pre-connected two-part ZSI 375 device.

Figure 2.

Device preparation. A, Filling the hydraulic circuit with 4.5 mL saline using the septum of the cuff; B, filling the compensation pouch with 4.5 mL saline.

Figure 3.

Pump unit. A, Deactivation button, B, Activation button, C, Pump button.

The implantation procedure was carried out under general anaesthesia with the patient in the lithotomy position. We used a traditional surgical technique consisting of a perineal incision for cuff placement and a scrotal incision for pump and tank placement. Exceptionally, a perineal approach only was used and the compensation pouch was made with the index finger. A 14- or 16-F Foley urethral catheter was placed for guidance. After setting the sphincter closure pressure range (60–70, 70–80 or 90–100 cm H2O) using the spring, the pump unit was placed in the scrotal compensation pouch. Pressure could be increased in situ by trans-scrotal injection of saline into the pouch; 1 mL saline increased pressure by about 10 (range 8–12) cm H2O.

Patients were discharged once they could void spontaneously. The device was activated 8 weeks later by pushing the activation button (Fig. 3B). To void, patients had to squeeze and release the pump button (Fig. 3C). The saline solution drawn from the cuff unit into the pump unit released the pressure around the urethra. The cuff automatically re-inflated within 150 s.


Urine analysis, bladder ultrasonography to evaluate residual urine volume, and flow rate measurements were performed at 1, 2, 4, 6, 12, 18 and 24 months after implantation. Patients recorded the number of pads used per day in a 7-day diary before their visits at 1, 2, 6 and 12 months. Total continence was given by use of 0 pads (i.e. completely dry), social continence as daily use of 1 or 0 pads, and incontinence as daily use of >1 pad. Success was defined as total or social continence and improvement as a decrease in daily pad use.



From May 2009 to April 2011, 36 patients, with a mean (range) age of 63 (53–86) years, with moderate-to-severe stress urinary incontinence underwent implantation of a ZSI 375 device in our two centres. Incontinence was secondary to RP (n= 28), TURP (n= 6) or bladder replacement (n= 2). The perineal plus scrotal approach was used in 32 patients and the perineal approach only was used in four patients. The mean hospital stay was 3 days and the median (range) follow-up was 15.4 (6–28) months.


Implantation and recovery were uneventful in 32/36 patients. No patient experienced bladder overactivity, chronic urinary retention, or any other adverse effect after device activation. Two patients with placement of a 14-F Foley catheter presented with urinary retention after catheter removal and required placement of a supra-pubic catheter until healing and before pump handling. A 16-F Foley catheter was used for subsequent procedures.

Complications leading to device removal arose in 4/36 patients (one case of erosion and three of infection). The case of erosion arose in one of the two patients with urinary retention after catheter removal. Infection in one patient was secondary to urethral injury during procedure; the device was removed 5 days after implantation. Two patients, one with a thick scrotum, who underwent pump implantation via a perineal incision encountered problems with pump manipulation and underwent a second procedure for pump placement in another subdartos scrotal pouch via a scrotal incision. One of these patients presented with a trans-scrotal extrusion of the pump unit. The device was removed in both patients.


Before device implantation, all patients used ≥2 pads for incontinence and three patients used penile sheaths. At 3 and 6 months after implantation, 28 (78%) and 26 (73%) of the 36 patients, respectively, used 0 or just 1 pad per day (social continence [Table 1]).

Table 1. Continence rates before and after device implantation
 Before implantation3 months after implantation6 months after implantation12 months after implantation
Patients, n36363624
Pads used/day, n (%)    
 None5 (14)4 (11)7 (29)
 123 (64)22 (61)12 (50)
 24 (11)5 (14)4 (11)2 (8)
 310 (28)001 (4)
 ≥421 (58)3 (8)5 (14)2 (8)
Success (0 or 1 pad), n (%) 28 (78)27 (75)19 (79)
Improvement, n (%) 4 (11)4 (11)2 (8)
Failure, n (%) 4 (11)5 (14)3 (13)

Of the 14 patients implanted with a 60–70 cm H2O pressurized device, only one had social continence on device activation. Incontinence persisted in the 13 others because of a lack of pressure in the cuff. Pressure was therefore increased by in situ trans-scrotal injection of ≥2 mL saline into the compensation pouch. Social continence was achieved in 12/13 patients; continence improved from 4 to 2 pads/day in 1/13 patients. All three patients receiving a 70–80 cm H2O pressurized device had persistent incontinence on device activation because of a lack of pressure. Social continence was achieved in all three by trans-scrotal injection of at least 1 mL saline. Of the 11 patients implanted with a 90–100 cm H2O pressurized device, one achieved social continence on device activation and two after trans-scrotal injection of 1 mL saline to increase pressure.


Preliminary efficacy results were highly similar to those for the AMS 800 (American Medical Systems, Minnetonka, MN, USA). Total continence, as evaluated by pad use, was achieved in 3/4 patients using the ZSI 375 and was stable over 12 months. Continence was improved in a further 11% of patients. Data from the Food and Drug Administration in the USA give a 73% total continence rate for the AMS 800 and an 88% improvement rate [11].

The ZSI 375 was designed to simplify AUS implantation because of the long learning curve needed to achieve mastery of the implantation procedure, to manage complications, and to perform surgical revisions. In the present series of implantations, complications and revision rates were similar to those for the standard AUS that is in current use, the AMS800, with surgeons trained in AUS surgery [12–15].

An interesting feature of the ZSI 375 device is the absence of an abdominal reservoir. The abdominal reservoir of the AUS was a fixture designed at a time when most cases of male urinary incontinence were still secondary to surgery for prostate adenoma; however, with the development of RP for the treatment of localized prostate cancer and of post-cystectomy bladder replacement, the number of procedures in the USA rose from 2500 to 6000 between 2001 and 2004 [9]. The abdominal approach for reservoir placement can be tricky, especially in cases of widespread sub-peritoneal detachment of pelvic tissue during laparoscopy. It has given way to ectopic placement (preperitoneal or lumbar/iliac region) of the pressure-regulating balloon [16]. However, using a pressure-regulating spring in the intrascrotal pump, as in the ZSI 375 device, instead of an abdominal reservoir has greatly simplified the procedure, reducing operating time and risk of infection. On the one hand, operating time is further reduced by use of a pre-connected device. In addition, the risk of air in the tube and of filling fluid leakage into the tube is lower. On the other hand, the ZSI 375 pump size is larger than the AMS 800 pump size but similar to that for penile implants.

Although our median follow-up of 15.4 months was long enough to establish the safety and efficacy of the ZSI 375 device, it may not have been long enough to identify all potential complications. The reported mean time of complication onset for AUS is 19.8 months for erosion, 29.6 months for atrophy, and 68.9 months for mechanical complications [17]. The present study has further limitations: its design was retrospective, the sample size was rather small, and assessment of continence was based on pad number and not on pad weight and did not use self-administered questionnaires.

A longer follow-up is therefore needed to confirm these early results and further research is warranted. For instance, we used the perineal approach to compare results with those for the AMS 800 device and to skirt the controversy about the peno-scrotal approach [5,9,18,19]. However, it should theoretically be possible to achieve analogous efficacy with the peno-scrotal approach as the cuff of the ZSI 375 device can be adjusted to the exact diameter of the urethra. This approach is currently under investigation.

In conclusion, despite being a simpler procedure, ZSI 375 implantation remains a procedure for surgeons trained in AUS surgery in centres of excellence as is already the case for penile prosthetic surgery [20].


Christophe G-Llorens is a Stock Holder and Patent Inventor for Mentioned Product and Yves Leclerc is a Paid Consultant to Sponsor.