Clinically reviewed by
Honorary Associate Professor Jeremy Ockrim
Consultant Urological Surgeon · Reviewed June 2026 · Review due June 2027
What is Sacral Neuromodulation?
Sacral neuromodulation (SNM) is a proven, minimally invasive therapy that uses gentle electrical impulses to modulate the sacral nerves responsible for controlling bladder and bowel function. By influencing the signalling between these nerves and the brain, SNM can restore more normal control in patients who have struggled with troublesome urinary or bowel symptoms.
The Medtronic InterStim™ system is the world's first and most established SNM therapy, with over 30 years of clinical experience and more than 475,000 patients treated globally. Axonics™ Boston Scientific is also available as an alternative system for selected patients.
SNM is indicated for patients whose symptoms have not responded to behavioural modifications, pelvic floor exercises or medications — offering a chance of meaningful symptom control where other options have fallen short.
Conditions Treated
Sacral neuromodulation is used to treat a range of bladder dysfunction conditions when conservative treatments have not delivered adequate symptom control.
Overactive Bladder (OAB)
Urgency, frequency and nocturia that has not responded to bladder retraining or medication.
Find out more →Urinary Incontinence (urge / mixed)
Urge or mixed urinary incontinence where leakage is driven by bladder overactivity.
Find out more →Non-Obstructive Urinary Retention
Difficulty emptying the bladder in the absence of a physical obstruction, including Fowler's syndrome.
Find out more →Bladder Pain Syndrome
Chronic pelvic and bladder pain with urinary urgency unresponsive to first-line therapies.
Find out more →How Sacral Neuromodulation Works
A small implantable device sends mild electrical impulses to the sacral nerves — specifically the third sacral nerve (S3) at the base of the spine. These nerves carry the signals that control the bladder, bowel, pelvic floor and urinary sphincter.
By modulating these signals, SNM helps restore a more normal pattern of communication between the pelvic organs and the brain. In patients with overactive bladder, this can reduce involuntary bladder contractions; in those with non-obstructive retention, it can re-establish the ability to empty the bladder.
Patients usually feel only a gentle, comfortable tingling sensation in the pelvic area when the device is active, and the level of stimulation can be fine-tuned to each person.
The Two-Stage Procedure
SNM is performed in two distinct stages so that we can be confident the therapy will work for you before proceeding to a permanent implant.
Stage 1: Trial Evaluation
A thin, flexible lead is placed alongside the sacral nerves under general anaesthetic with X-ray guidance, usually as a day case. The lead is connected to a small external stimulator that you wear for one to two weeks.
During the trial you keep a bladder or bowel diary to track your symptoms. The trial is considered successful if you experience at least a 50% improvement compared with baseline.
Stage 2: Permanent Implant
If the trial is successful, a small implantable pulse generator (the size of a small matchbox) is placed under the skin in the upper buttock, connected to the lead alongside the sacral nerves.
This is performed as a day-case procedure under general anaesthetic. Most patients go home the same day and resume light activity within a few days.
Your clinician will discuss the device options available to you and recommend the system best suited to your needs, anatomy, and lifestyle preferences.
The Medtronic InterStim™ System
Trusted Technology, Proven Results
London Urology Specialists partners with the Medtronic InterStim™ system — the world's most established sacral neuromodulation therapy with over 30 years of clinical data. Two device options are available, allowing us to tailor the choice to each patient's lifestyle and preferences.
InterStim™ X
A recharge-free, battery-powered device — no daily or weekly charging required.
- • Lasts approximately 10–15 years
- • No charging routine to maintain
- • Suited to patients who prefer a fit-and-forget device
InterStim™ Micro
A rechargeable device — smaller and lighter than previous generations.
- • Lasts up to 15 years with regular charging
- • Smallest InterStim device available
- • Suited to patients who prefer a smaller implant
Key features of the InterStim™ system
- ✓ MRI conditional — full-body 1.5T and 3T MRI scans possible
- ✓ Smart programming via the Medtronic Smart Programmer
- ✓ 30+ years of clinical evidence
- ✓ FDA approved and CE marked
- ✓ NICE recommended for refractory overactive bladder and non-obstructive urinary retention
- ✓ Adjustable settings tailored to each patient
Partnership note: London Urology Specialists is proud to be supported by Medtronic UK in providing this advanced therapy to our patients.
475,000+
Patients treated with InterStim™ therapy worldwide
Medtronic provides a dedicated library of patient videos covering what to expect from SNM therapy, the implant procedure, and life with an InterStim™ device.
Watch the Medtronic patient videosAlternative System
An alternative sacral neuromodulation system is also available — the Axonics® Boston Scientific R20. Your consultant will discuss the options with you and recommend the system best suited to your individual needs.
Key features of the Axonics R20 system
- ✓ Lasts up to 15–20 years with regular charging
- ✓ Battery recharging every 6 to 10 months depending on therapy settings
- ✓ MRI conditional — full-body 1.5T and 3T scans supported (as long as lead integrity is maintained)
- ✓ FDA approved and CE marked
- ✓ NICE recommended for refractory overactive bladder and non-obstructive urinary retention
- ✓ Adjustable settings tailored to each patient
Your consultant will discuss both options with you and recommend the system best suited to your needs, anatomy, and lifestyle preferences.
What to Expect
Our SNM pathway is structured around careful assessment and a staged approach. Around 60–80% of patients who proceed to a permanent implant experience significant improvement in their symptoms.
1. Assessment
Detailed consultation with one of our specialist consultants, symptom diary review, urodynamics where indicated, and shared decision-making.
2. Trial Implantation
A thin lead is placed alongside the S3 nerve under general anaesthetic with X-ray guidance, connected to an external stimulator. Day-case procedure with rapid recovery.
3. Trial Review at 1–2 weeks
We compare your symptom diary against baseline. A ≥50% improvement is considered a successful trial and justifies a permanent implant.
4. Permanent Implant (if successful)
The battery is implanted under the skin in the upper buttock as a day-case procedure. Most patients are home the same day.
5. Follow-up Programming
Settings are fine-tuned at follow-up appointments to optimise your response, with adjustments made non-invasively using the phone app or Smart Programmer.
6. Long-Term Review
Annual reviews monitor your symptoms, battery status, and overall wellbeing — with onward planning for device replacement when needed.
Recovery & Living with SNM
Most patients return to normal life very quickly. After the permanent implant, the device is barely noticeable and all aspects of daily life can be resumed without restriction.
- ✓Trial period: Keep the lead site dry, avoid heavy lifting, and continue normal day-to-day activity.
- ✓Permanent implant: A small incision in the upper buttock heals within 1–2 weeks.
- ✓Device awareness: The implant is small and most patients quickly forget it is there.
- ✓Daily life: You can drive, work, travel and exercise normally once the wound has healed.
- ✓Battery checks: Battery status is monitored at routine follow-up appointments.
- ✓Programming: Settings can be adjusted by your clinician at any time using the phone app or Smart Programmer.
Benefits & Considerations
Benefits
- ✓Fully reversible — the device can be removed at any time
- ✓Minimally invasive day-case procedure
- ✓Adjustable settings tailored to your symptoms
- ✓MRI compatible (1.5T and 3T full-body scans)
- ✓Does not preclude other future treatments
- ✓Long battery life
Considerations
- !Surgical procedure with a small risk of bleeding or infection
- !Some patients may feel the device under the skin
- !Battery may need replacing in future (or regular recharging for rechargeable devices)
- !There can be a short learning curve when adjusting programming
- !Lead migration (displacement) is uncommon but can occur
- !Not every trial is successful — around 20–40% do not proceed to implant
Frequently Asked Questions
Meet your Specialists
Our experienced consultant urological surgeons perform sacral neuromodulation across a range of bladder and pelvic floor conditions.
