Display Patient Information Leafelts

Sacral Neuromodulation

Date issued: December 2021 

Date reviewed: December 2023

Ref: B-334 v5

PDF: Sacral Neuromodulation final December 2021 v5.pdf [pdf] 422KB

What is Sacral Neuromodulation (SNM)?

SNM is an implanted system which can help to improve your bladder and / or bowel function by sending electronic signals to the nerves that control your pelvic floor.

The device is inserted into the lower part of your back and consists of a lead and battery placed in your buttock.

It involves the placement of a needle into one of the naturally occurring holes (foramen) in the sacrum, which then has a lead (with electrodes) passed through. We use guided x-ray to locate the foramen. The lead lies alongside the sacral nerves of S3-S4 where the nerves supply the organs of the pelvis and the pelvic floor muscles. Regular gentle pulses of electricity are passed along the lead from a small battery pack.

Why are we suggesting Sacral Neuromodulation?

You have been under the care of the Colorectal, Uro-gynaecology or Urology team to manage your bladder and/or bowel issues. If you have already tried and failed the conservative and medical treatments, sacral neuromodulation may ease and possibly resolve the urinary and bowel symptoms.

This device does not work for everyone (approx. 80%) which is why all patients have to undergo a test phase to see whether they respond to treatment. We hope that the device will significantly improve your symptoms, but it may not completely cure them.

What are the alternatives to this procedure?

Adjusting your food / fluid intake, bladder retraining, physiotherapy and pelvic floor exercises, rectal irrigation, ISC, drug treatment, sphincter repair or other surgical treatments.

Sacral Neuromodulation (SNM) is not effective for everyone and does not work for approximately 1 in 5 (80%). We therefore do a 2?3 week trial of nerve stimulation to see if it will benefit you. Not all patients are suitable for this type of treatment and if this is the case for you, it will be discussed fully in your consultation.

We use devices from 2 companies, either Medtronic or Axonics. Your Pelvic Floor Nurse will have discussed the 2 options with you and given you the company literature. We would like you to read the information and even visit the company websites for further information. If you have any questions, please do discuss them with your Pelvic Floor Nurse.

What is the process of SNM

You will be reviewed by one of our specialist nurses in SNM who will discuss the treatment with you and assess your suitability. You will be given bladder / bowel diaries to complete and return to the nurses and sometimes a quality of life questionnaire. This paperwork gives us important information and without this paperwork we will be unable to proceed with the procedure.

There are two stages to SNM, the test phase (advanced trial) and the second phase.

Both stages involve coming into hospital as a day case to have the lead inserted and then returning for a second operation.

Test phase: Operation 1: Permanent lead inserted (Sedation and local anaesthetic)

Second Phase: Lead removed if the trial is unsuccessful or battery added for it to become a full implant (Local anaesthetic to have the battery inserted or sedation and local anaesthetic to remove the lead)

There are currently two companies who provide the devices; Medtronic and Axonics. Both companies offer rechargeable devices and Medtronic a non-rechargeable device. Your nurse will discuss your suitability for device with you and we would encourage you to look at the company websites for further information.

What should I expect before the procedure?

You will be admitted on the day of your surgery. You will normally receive an appointment for pre?assessment prior to the admission to assess your general fitness and screen you for a germ (bacteria) called MRSA and MSSA alongside some baseline observations – blood pressure, heart rate, current medication and details of your medical history. You will also be sent instructions regarding eating and drinking prior to your admission. On admission you will be seen by the Consultant and the Pelvic Floor Nurse Specialist.

The advanced trial has three pieces of equipment

- Temporary external battery (white box)
- Handheld controller or fob to alter the intensity of the stimulation or to turn the device      on or off
- Tined Lead which is inserted into the lower back / spine in the sacrum

Test Phase

The procedure is performed in theatre, where the anaesthetist will give you sedation and you will have local anaesthetic at the wound sites. After the lead has been inserted it is covered by a large dressing and connected to the external battery and we will pair with a hand controller to deliver stimulation. When the implant is switched on you will feel a sensation in the genital, rectal or buttock area. The level of stimulation will be set so that you can just feel it. If you find the level of stimulation bothersome or painful you are able to turn it down and you will be given instructions on how to use the controller to do this. It will be advisable for someone to drive you home after the procedure.

The temporary battery and hand controller, permanent battery (Medtronic)
The temporary battery and controller, permanent battery (Axonics)

What happens during the trial period?

The test period lasts 2-3 weeks and during this time you can continue to lead your everyday life. You will be given dates by the nurse for a review and to discuss how the trial is going for you. You will have a bowel or bladder diary to complete during the trial period. It is important that you complete the diary, indicating how you are during the trial period.

You will have two wounds, one at the lower back and another on the buttock. It is important that the dressings covering your wounds and lead stay dry during the test period to prevent any wound infection occurring. We therefore request that you do not shower or bathe during this period and instead have a ‘strip wash’. If an infection were to occur it would mean that the lead would need to be removed and the trial would end.

If driving you will need to turn the stimulator off and back on again when you get out of the car. You don’t need to turn it off if you are the passenger. Those with an Axonic device are not required to do this.

You may return to work after a couple of days, but we would advise no heavy lifting, operating heavy machinery or excessive bending or stretching. If your employer cannot accommodate light duties, you may require time off work for the trial.

Please continue with your life as normally as possible. Carry on with work, light housework etc. Please avoid strenuous exercise, swimming, sexual activity or heavy lifting during the trial period.

You can remain on your current bowel/bladder medication, but you may want to try weaning yourself off them to see how you respond.

If you experience pain, switch the controller off and see whether the pain settles. If it does turn the level of stimulation down in the first instance and please discuss with your nurse

What happens at the end of the trial period?

If the trial has not been successful, the lead will be removed under sedation and local anesthetic. If successful, you will proceed to the second phase and the permanent battery is inserted under local anaesthetic. Both operations are performed in theatre but the second phase is usually performed at Tavistock Hospital.

Please bring your diary and controller back with you when you come for any appointments and on the day of admission for the second operation. We will discuss whether you have had an improvement with your symptoms and if the improvement has been sufficient, we will consider fitting a permanent battery (stimulator).

Are there any complications or risks?

Like all surgery there are some potential risks. Some of these risks relate to surgery and anaesthetics, while some risks are specific to this procedure.

The most commonly reported side effects are pain over the wound sites, bruising and wound infection. Occasionally patients will report a slight discomfort in their leg or foot. Should this happen we would advise patients to turn the level of stimulation down.

Risks specific to this procedure relate to the chance of nerve injury or bleeding within the pelvis due to placement of the wires. This complication occurs in less than 1% of patients but may result in further surgery being required.

If the lead needs to be removed there is a small risk that part of it will be left inside the body, it is unlikely that this will do you any harm in the future.

There is a potential for the lead to become displaced. We reiterate the importance of not doing any heavy lifting, repetitive exercises involving bending, or excessive movement of the lower back.

Contact sports or hobbies such windsurfing, horse riding, skiing, trampolining etc are just a few where you are at an increased risk of sustaining falls and therefore damage to the lead, therefore it may not be appropriate for you to have this device. You cannot dive below 10m of water or there may be problems with entering a hyperbaric chamber with having this device, due to the high pressure. Therefore it is important that you think about these things before deciding whether this device is suitable for you.

While this is now a well?established and safe operation there may be other risks and side effects that we are not yet aware of.

Second Phase

If the test period of Sacral Neuromodulation was successful for you, you will be asked to come in for insertion of the permanent battery (implant). This is also done as a day case, and involves a local anaesthetic.

The battery is placed under the skin of one of the buttocks and then connected to the stimulating lead through a small channel under the skin. The battery is very similar to a pacemaker used for heart patients (size of a matchbox). The Axonics battery is smaller again.

What happens immediately after the procedure?

After your operation, the implant may be switched on or you will be asked to come into clinic to have this done. You will be given a patient handset which the Pelvic Floor Nurse will set and teach you how to use it.

You can switch your battery on and off and turn the voltage up and down, by means of using the handset. We suggest that you initially keep your handset with you at all times, however you fill find as time goes on that you prefer to leave it at home.

Are there any risks / side effects?

Most procedures have a potential for side?effects. Some of the risks relate to surgery and anaesthetics, whilst some risks are specific to the procedure. You can be reassured that, although these complications are well recognised, the majority of patients do not suffer any problems. The significant risks specific to this operation are related to
• Nerve injury.
• Bleeding within the pelvis.
• Replacement, relocation or removal of the implant.
• Replacement, relocation of the lead.
• Pain in pelvis/leg.
• Inability to pass urine, requiring a bladder catheter.
• Wound infection at the site of the electrode or implant.
• Adverse effect on bowel function.
• Malfunction of the implant.

In the event that such occurs, you can switch the stimulator off with your handset.

What should I expect when I get home?

You will have a wound over your buttock where the battery has been implanted. It will have a shower proof dressing and glue to the wound, which is left undisturbed for 5 days. After 48 hours you can have a quick shower and then the dressing can be removed 5 days after the operation. From then on you can take quick showers but avoid soaking in the bath for at least a further week. Stitches are usually absorbable but if the Consultant has used non-dissolvable stitches, you will be advised.

If you experience any flu like symptoms, redness/throbbing in the wound, pain/burning when passing urine or difficulty passing a catheter, please contact the Pelvic Floor Nurse or if unavailable your GP or 111 if out of hours.

There is still a risk that the lead may move, especially as it will have only been two or three weeks since the lead was inserted. Continue to limit your activity to low or moderate levels up to three months post lead insertion. Avoid exercise which involves bending and stretching as this can cause lead movement.

If you experience new pain, try turning the battery off for a day. If the pain goes away, get in touch with us as it might be the level of stimulation causing the pain. If the pain persists with it turned off, it is unlikely to be caused by the battery, so make an appointment with your GP.

We would advise you to take approximately 1 week away from work to heal and recover following the second phase. Depending on your work we would advise no heavy lifting, operating heavy machinery or excessive bending or stretching for 6-12 weeks.


When you move (especially bending/twisting) the wire can move slightly in relation to the sacral nerves and the level of stimulation. This is normal but could feel uncomfortable and make you jerk suddenly. Medtronic advise you to turn the device off when driving or operating machinery but remember to turn it back on. There is a possibility that when you go through a security screen in shops or an airport it may switch the device off, or possibly trigger an alarm. You can check that your device is still switched on using your handset.

MRI scans can be performed with the new leads being inserted, however you will need to put the device into MRI safety mode beforehand and/or switch the device off.

You may require further contact with the Pelvic Floor Nurse Specialist to ‘fine tune’ your programmer. Over time, the body can become conditioned (used) to the programmer settings and you may need advice on re?programming.

The average time for a Medtronic battery to be replaced is 5-7 years and this is undertaken as a day case and using local anaesthetic. The life time of a rechargeable battery is approximately 15 years. If the lead becomes damaged or dislodged then replacing it will require a further operation with sedation and local anaesthetic.

What about travelling

The aim of the treatment is to improve your continence, with the result that you should be able to return to leading a normal life. There is no problem with travelling by aeroplane with the implant, but the scanner at security may affect your device. You will be given a card and a letter to carry after the operation, informing others that you have the device implanted. You can show this at security and ask to bypass the scanner. If you do pass through the scanner, it may turn your implant off. Do not worry, just use your handset to check afterwards, if you can no longer feel the sensation.

I can’t feel the sensation anymore

The body does get used to the sensation, so you may find it less obvious as time passes. You may find this particularly when you come to clinic and the settings are changed. The sensation will be obvious initially but after an hour or two less so. If you can’t feel the sensation anymore, check that the implant is on and turn the voltage up a bit and then reduce back to where you had it set.

I find the sensation uncomfortable. Is there anything I can do?

You do not need to feel the sensation in order for it to be effective. You could turn the voltage down to just below the level where you can feel it, so that it doesn’t bother you but is still doing its job.

Other useful information

If you are coming into hospital for a future operation please ask the pre-operative assessment nurse to let the Pelvic Floor Nurse know so that she can advise them. The sacral nerve stimulator will need to be switched off for any surgery you have and can then be switched on after surgery. The doctor performing the surgery will need to be advised that bi-polar diathermy will need to be used during your procedure.

If you think or know you are pregnant, the stimulator must be turned off immediately and the Pelvic Floor Nurse informed. It can be turned back on again after delivery.

In the event of death, the funeral directors would need to be informed that you had an implantable device by your family as it would need to be removed prior to cremation.

If you have any questions either before or after your surgery you can contact the Pelvic Floor Nurse, Monday to Friday, 9?4pm on 01752?431166. Outside of these hours you may leave a message on this number. We will aim to answer your query within 48hours. Alternatively you can email your query to ann.cornelius@nhs.net



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