Sacral neuromodulation

Here is how it works: a small wire (called an electrode) is placed near the sacral nerves (S3) at the base of your spine — the nerves responsible for telling your bowel when to hold and when to release. That wire connects to a tiny pulse generator (the device itself) implanted just under the skin of your buttock. Together they send gentle, continuous electrical signals that help your brain and bowel communicate better.

The good news is that before you commit to anything permanent, you get to try it first. The procedure is done in two stages — a trial phase lasting 2–4 weeks where you wear an external device and see how much it helps, followed by permanent implantation only if the trial shows meaningful improvement (generally more than a 50% reduction in leakage episodes). If the trial does not help, the wire is simply removed.

• You have faecal incontinence (leakage of stool) that has not improved with diet changes, medications, or pelvic floor physiotherapy
• Your sphincter muscle is intact or has already been repaired — SNM can help even if there is a small remaining gap in the muscle
• You experience urge incontinence — where you feel the urge and cannot make it to the toilet in time — which responds especially well
• You have passive incontinence — where leakage happens without you realising
• A previous sphincter repair has not given you the improvement you hoped for
• You prefer not to have, or are not suitable for, sphincteroplasty (sphincter repair surgery)

• In published series, around 70–80% of patients who undertake the trial see at least a 50% drop in leakage episodes and proceed to permanent implantation
• Completely reversible — the device can be adjusted, turned off, or removed at any time
• Helps with both urge and passive incontinence
• Avoids the longer recovery of open sphincter repair surgery
• Durable — published long-term studies show the benefit is maintained in most patients beyond 5 years
• If you also have urinary urgency or leakage, SNM can help with that too

• Infection at the implant site — occurs in about 3–5% of patients. Some cases settle with antibiotics, but a deep infection involving the implant typically requires removing the device (and reinserting later, once the infection has fully cleared)
• Lead migration — the wire can shift position in 5–10% of cases, sometimes needing a small procedure to reposition it
• Battery life depends on the device — non-rechargeable systems (Medtronic InterStim) typically last 5–10 years, while rechargeable systems (Axonics) typically last around 15 years — a straightforward procedure replaces just the pulse generator (the battery part), not the lead
• Discomfort at the implant site — affects about 5–10% of people, often settles on its own or with device adjustment
• Device malfunction — uncommon; easily identified at follow-up checks
• MRI scans — Axonics is approved for full-body MRI under MR-conditional settings, and modern Medtronic InterStim devices are approved for 1.5T head and extremity MRI. You will need to tell any imaging centre that you have an implant so they can confirm the protocol first

If you take blood thinners, diabetes medication, GLP-1 weight-loss injectables, or iron supplements, please flag this when you book — these need specific adjustments before the procedure. Full details are in the guide above.

• Before the trial, you will have anorectal manometry (a short pressure test) and an endoanal ultrasound (an internal scan of the sphincter muscles) — these tests give a clear picture of how your bowel is working before treatment. The manometry is done in the rooms; the endoanal ultrasound is done at Warringal Private Hospital alongside the trial procedure or an EUA.
• You will be asked to keep a bowel diary for a few weeks before the trial — this helps measure how much improvement the device actually makes
• You will be prescribed antibiotics to take around the time of the procedure
• Both stages of the procedure will be explained fully and any questions you have will be answered before you consent

• Stage 1 — the trial: This is a day procedure at Warringal Private Hospital or Epworth Eastern, done under local anaesthetic with light sedation so you are relaxed and comfortable. A thin wire is placed near the sacral nerve (S3) in your lower back using X-ray guidance, and connected to a small external device you wear on your belt or in a pocket. You go home the same day.
• You use the trial device for 2–4 weeks at home and keep a diary of your symptoms. If you see a clear improvement, you move on to Stage 2.
• Stage 2 — the permanent implant (if the trial works): Done at Warringal Private Hospital or Epworth Eastern under general anaesthetic. The permanent electrode is secured in place and the pulse generator is implanted just under the skin of your buttock through a small incision. It sits flush under the skin — you can feel it but it is not visible through clothing.
• The device is switched on and programmed to your comfort level before you leave
• Most patients go home the same day or stay one night

• During the trial (weeks 1–4): You can go about your normal life. You will manage the external device yourself at home — it is straightforward to use and the team will show you how
• If the trial does not help enough: the wire is removed as a simple outpatient procedure and no permanent implant is placed
• After permanent implantation: Keep activity light for the first 2 weeks and avoid bending deeply or twisting at the waist while the wound heals
• By week 4: You can return to your normal activities including exercise
• The device settings are fine-tuned at follow-up appointments — small adjustments can make a big difference to how well it works
• Long-term: you will have an annual check-up and, when the battery eventually runs low (typically after 5–10 years for non-rechargeable devices, or around 15 years for rechargeable ones), a simple procedure replaces just the generator
• You will be given a device ID card to carry — show it at airports and tell any doctor or radiologist about your implant before scans
• A post-operative review is routinely arranged 2–6 weeks after your procedure — this review is provided at no charge
• For day-by-day guidance on wound care after permanent implantation, device settings, and what to expect during the trial, see the Post-sacral-neuromodulation aftercare guide on the Resources page.

Post-operative concerns: Please call our rooms on (03) 9816 3951 and leave a message — this will be sent directly as a text to Mr Nguyen. Alternatively, you may text the office mobile on 0499 090 126. We aim to respond promptly during business hours.

Emergencies: For any life-threatening emergency, call 000 immediately or go to your nearest emergency department. Do not wait for a call back from our rooms. For the Austin Hospital Emergency Department: (03) 9496 5000.