Artificial Urinary Sphincter (AUS)
The artificial urinary sphincter (AUS) is the gold standard surgical treatment for moderate-to-severe male stress urinary incontinence (SUI), particularly following prostate surgery. The AMS 800™ is the predominant device, in clinical use since 1972 with more than 250,000 implanted worldwide. It provides durable continence restoration through a completely implantable, fluid-filled hydraulic system that mimics voluntary sphincter function.
Device Components
The AMS 800 consists of three silicone components connected by kink-resistant tubing forming a closed hydraulic circuit:
| Component | Location | Function |
|---|---|---|
| Occlusive Cuff | Bulbous urethra (men) or bladder neck | Applies circumferential compression to maintain continence; 13 sizes (3.5–11.0 cm) |
| Pressure-Regulating Balloon (PRB) | Prevesical (space of Retzius) | Maintains constant system pressure; most common range 61–70 cmH₂O |
| Control Pump | Scrotum (men) / labia majora (women) | Patient-operated valve mechanism; contains a deactivation button to keep cuff open |
Many components are coated with InhibiZone™ — silicone impregnated with rifampin and minocycline hydrochloride — to reduce bacterial colonization at implantation.
System Operation
The AUS cycles between continence and voiding by fluid transfer between the cuff and balloon:
- At rest (continent): Cuff is inflated, applying urethral compression sufficient to prevent leakage.
- To void: Patient squeezes and releases the scrotal pump several times, transferring fluid from the cuff → PRB, deflating the cuff and opening the urethra.
- Auto-refill: After approximately 1–11 minutes (depending on component size), the PRB passively returns fluid to the cuff, restoring continence without patient action.
Indications
Primary indications for AUS implantation:
- Moderate-to-severe SUI (typically >2 pads/day, or 24-hour pad weight >400 g) after prostate surgery — accounts for >90% of male implants
- Failed conservative management (pelvic floor physiotherapy, behavioral modification)
- Intrinsic sphincter deficiency from radical prostatectomy, cryotherapy, HIFU, TURP, or radiation
- Neurogenic bladder with SUI in select patients with adequate dexterity
- Women with severe SUI refractory to other treatments (limited data)
Absolute contraindications: Active UTI or urethral erosion, inadequate manual dexterity to operate the pump, uncontrolled detrusor overactivity incompatible with safe storage pressures.
Preoperative Assessment
| Evaluation | Purpose |
|---|---|
| Cystoscopy | Exclude urethral stricture, bladder neck contracture, bladder pathology, cancer recurrence |
| Urodynamics | Assess storage parameters; essential in neurogenic patients or complex histories |
| 24-hour pad weight | Quantify severity; >400 g favors AUS over sling |
| Manual dexterity assessment | Patient must reliably operate scrotal pump |
| PSA | Exclude cancer recurrence prior to implant |
| Infection screening | Clear any UTI before proceeding |
Surgical Technique
Approaches
Perineal approach (traditional, most common)
- Midline perineal incision for cuff dissection around the bulbous urethra
- Separate small lower abdominal / inguinal incision for PRB placement
- Optimal visualization; favored for primary implants
Transverse scrotal / penoscrotal approach
- Single-incision access to the proximal bulbar urethra
- Shorter operative time (mean ~28 min); comparable outcomes in experienced hands
- Some series report slightly lower dry rates vs perineal approach
Bladder neck placement
- Used primarily in women and children, or men with bulbar urethral compromise
- Requires suprapubic incision; higher erosion risk
Transalbugineal approach (emerging)
- Cuff passed through the tunica albuginea of the corpora cavernosa
- May reduce erosion risk while preserving erectile function in select patients
Key Principles
- Cuff placed around bulbous urethra in the majority of men; size typically 3.5–6.0 cm
- PRB placed in the space of Retzius (prevesical space)
- Meticulous hemostasis and atraumatic tissue handling to minimize urethral injury
- Perioperative antibiotic prophylaxis; InhibiZone coating provides additional protection
- Device left deactivated at closure; activated 6 weeks postoperatively once tissues have healed
Outcomes
Continence
| Endpoint | Rate |
|---|---|
| Social continence (0–1 pad/day) | 60–83% |
| Total dryness (0 pads/day) | 51–60% at 12 months |
| >50% pad weight reduction | ~94% at 12 months (AUSCO trial) |
| Patient satisfaction | >80%; 92–99% would recommend or repeat the procedure |
The prospective multicenter AUSCO trial (Kaufman et al., J Urol 2025) demonstrated 94% of patients achieved >50% pad weight reduction and 60% reported zero pad use at 12 months, with significant quality-of-life improvements across all validated instruments.
Institutional volume effect: Higher-volume centers demonstrate better continence and lower revision rates — patient referral to experienced implanting surgeons is recommended.
Complications
Early
- Urinary retention: ~5.8%
- Hematoma / seroma
- Wound infection
Late (requiring reoperation)
| Complication | Rate |
|---|---|
| Infection | 0.5–10.6% |
| Urethral erosion | 2.9–12% |
| Mechanical failure (fluid leak, pump failure) | Most common long-term complication |
| Urethral atrophy (recurrent incontinence with functional device) | 1.6–11.4% |
Infection and erosion often occur together and mandate complete device explantation. Risk is substantially higher in radiated patients and those with neurogenic bladder. A minimum 3-month waiting period before reimplantation is generally recommended; the salvage wash-out technique (immediate reimplantation with antibiotic irrigation) can be considered in select non-eroded cases.
Revision and Long-Term Durability
Revision burden is a critical counseling point — approximately 50% of patients require reoperation within 10 years:
| Timepoint | Revision-free survival |
|---|---|
| 1 year | ~94% |
| 2 years | 71–88% |
| 5 years | 57–62% |
| 10 years | ~40% |
Median time to first revision: 6.6 years (Lenfant et al., J Urol 2025).
Causes of revision
- Nonmechanical failure (56.5%): Urethral atrophy, persistent/recurrent incontinence despite functioning device
- Mechanical failure (27.6%): Fluid leak, pump malfunction, tubing kink
- Other (15.9%): Pump malposition, balloon herniation, pain
Risk factors for earlier revision
- Larger cuff size (HR 1.04–1.05 per cm)
- Pelvic radiation (median failure 26.4 vs 35.6 months in non-irradiated)
- Diabetes mellitus
- Poor ASA physical status
- Prior incontinence surgery
- Low institutional implant volume
Redo surgery
Patients undergoing second or third AUS implantation can achieve revision-free survival comparable to their primary device. Multiple risk factors (radiation + prior revision + large cuff) substantially reduce durability.
Special Populations
Post-radiation: Earlier device failure but still meaningfully effective; patients should be counseled on reduced durability and higher erosion risk.
Neurogenic bladder: AUS can be offered to selected patients with adequate upper extremity function; bladder storage parameters must be optimized (often with antimuscarinic therapy or Botox) before implantation to avoid unsafe storage pressures with a competent outlet.
Concurrent penile prosthesis: Simultaneous or staged implantation can be safely performed in experienced hands; careful attention to scrotal pump positioning avoids device-on-device interference.
Women: AUS via bladder neck cuff is an option for severe SUI refractory to all other interventions; data are more limited than in men.
Postoperative Management
- Deactivation period: Device remains deactivated for 4–8 weeks (typically 6 weeks) to allow tissue healing around the cuff before first activation
- Activation visit: Clinician confirms wound healing and trains patient on pump cycling technique
- Patient ID card: Patients carry a permanent card identifying the implant; emergency staff must be informed — no urethral catheter or instrument should be passed without first deactivating the device
- MRI compatibility: Varies by component generation; device identification and manufacturer consultation required before any MRI
Counseling Summary
| Point | Detail |
|---|---|
| Social continence probability | ~80% (0–1 pad/day) |
| Complete dryness probability | ~50–60% |
| Revision likelihood at 10 years | ~50% |
| Patient satisfaction | >90% would repeat the procedure |
| Device lifespan | Lifelong implant; manual operation required daily |
| Medical precaution | Must deactivate before any urethral instrumentation |
References
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