Information alert

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Your consultant has recommended that you have a muscle biopsy to help make a diagnosis of your condition; this may also help decide what the best treatment is for you.

This booklet has been written by the neuromuscular team at The National Hospital for Neurology and Neurosurgery. Our aim is to explain what a muscle biopsy is, how it is performed and what you are likely to experience.

This booklet is intended for patients (or their family or carers) who may be offered this procedure. It is not intended to replace discussion with your consultant.

If you have any questions about this procedure, please contact a member or our team.

A biopsy is a procedure in which small samples of tissue are removed. This tissue is examined under a microscope for abnormalities that may reveal important information about your condition. 

Three biopsy samples are usually taken for examination:

  • the first is about a centimetre in length and about the same width as a matchstick (about two millimetres);
  • the other two are around two centimetres in length and one centimetre in width (similar to the width of a biro/ballpoint pen). 

The samples are usually taken from the upper, outer thigh muscle (the quadriceps muscle) but other muscles are sometimes selected by your doctor including the arm muscles (biceps or triceps) or the calf muscle. 

The biopsy will take around 20 to 30 minutes.

There are several techniques that can be used. The needle biopsy is less invasive but in certain circumstances an open biopsy may be required.

Needle biopsy: This is performed in an adequately ventilated outpatient clinic room or ward bed. A specially designed instrument is passed through a 1-2 cm cut in the skin into the muscle. Adhesive strips rather than stitches close the wound. 

Open biopsy: This is performed in theatre. A 4-5 cm cut is made through the skin, exposing the muscle underneath and the wound is closed with stitches. The stitches will either be dissolvable or will need to be removed one week later.

A muscle biopsy can help in diagnosing conditions associated with muscle weakness. By looking at the muscle tissue under a microscope and doing other additional laboratory tests the cause of the muscle weakness can often be determined.

Sometimes a muscle biopsy is useful for investigating some rare conditions that do not directly cause muscle symptoms. For example, a muscle biopsy may be carried out when investigating heart problems or rare brain disorders. It can also help in the diagnosis of conditions causing inflammation of the blood vessels (called vasculitis).

A muscle biopsy will often give your doctors further information so that they can advise you better about the cause and likely course of your condition. However, you should be aware that there are no guarantees that this procedure will be helpful.

All invasive procedures have risks and your doctor will discuss the risks of a muscle biopsy with you.

The commonly occurring ones are:

Problems that may happen straight away:

The most common problem is pain at the site of the biopsy after the local anaesthetic wears off. It is important that you ask your nurse for pain relief when you need it.

In most cases this will stop in a few days to weeks. A small amount of bleeding or discharge from the wound may occur for two or three days. 

Swelling and bruising often occurs but should go away in a few days.

On extremely rare occasions an allergy to the medicines or dressings used may develop. If this happens treatment may be required in or out of hospital.

Problems that may happen later:

Infection (although rare) may occur as with any wound. However, it is more likely to occur if you have diabetes or you are taking medicines called steroids. If infection develops, wound healing may be slow and poor. A wound infection may require prolonged wound dressing and antibiotics and you may be left with a larger scar.

Problems that are rare:

Some people experience ongoing pain at the biopsy site or persisting numbness overlying the scar. Occasionally it is necessary to use medicines or other techniques to ease ongoing pain.

On very rare occasions, swelling and bruising at the wound site may remain for weeks after and it is possible that a hard lump (haematoma) may develop under the skin. This is generally accompanied by pain around the biopsy area.

The choice to have a muscle biopsy is yours. However, decisions about future treatments may depend upon the biopsy result, especially if long term or potentially toxic treatments are being considered.

We would not wish to give you such treatments without good evidence that it is right for you.

If you are uncertain about any aspect of the procedure, the reasons for it, the benefits or the possible risks and complications, please speak to your doctor.

Before considering a muscle biopsy your doctor will have gathered as much information as possible through blood tests (including genetic blood tests and autoantibody testing) and electrical studies. An MRI scan of the muscles may sometimes be helpful.

In some cases, a biopsy of skin or other body tissues can help.

We want to involve you in all decisions about your care and treatment. If you decide to go ahead with this procedure, by law we must ask for your consent and will ask you to sign a consent form. This confirms that you agree to have the procedure and understand what it involves. Staff will explain all the risks, benefits and alternatives before they ask you to sign a consent form. If you are unsure about any aspect of your proposed treatment, please don’t hesitate to speak to a senior member of staff again.

Your doctor needs to know about all medicines you are taking; especially those which affect the blood’s ability to form a clot such as:

  • anticoagulant (e.g., apixaban, dabigatran, edoxaban, enoxaparin, fondaparinux, heparin, rivaroxaban, warfarin) or 
  • antiplatelet medicines (e.g., clopidogrel or aspirin and other non-steroidal anti-inflammatory drugs such as ibuprofen, naproxen or diclofenac), as these may need to be stopped before the procedure. 

Do not stop taking any medicines unless you are advised to do so by your consultant or clinical nurse specialist.

If you are undergoing an open muscle biopsy, you may be admitted to the Day Care Unit, one of the wards or the Neuromuscular Complex Care Centre prior to your biopsy. We will send you information about the units with your admission letter. If you are undergoing a needle-muscle biopsy this is likely to occur in an outpatient setting.

Please bring any medicines you are currently taking with you on the day.

You will not need to fast for the biopsy as it is performed under a local anaesthetic. This means you will be awake throughout. If you would prefer to have sedation for the biopsy, please ask the team doing the procedure. We recommend that you have someone to accompany you on your homeward journey.

  • The health care professional performing the biopsy will not be the doctor looking after you, but will be a trained health care professional.
  • The health care professional doing the biopsy will ask you to lie on your back or will position you so that the muscle the biopsy is to be taken from is easy to access.
  • The health care professional will sterilise the area with iodine or other cleaning solution. A local anaesthetic (numbing medicine) will be injected around the area which initially causes a stinging sensation. Once the area is numb, a 1-2 centimetre (needle-biopsy) or a 4-5 centimetre incision (open biopsy) is made through the skin.
  • The health care professional then inserts a needle through the cut (needle-biopsy) or visually identifies the muscle (open biopsy) before taking the biopsy. Patients experience a ‘pulling’ or ‘pressing’  sensation as the biopsy is taken and some patients find this uncomfortable/painful.
  • Adhesive strips (needle-biopsy) or stitches (open biopsy) are used to close the skin and a dressing is applied. 

After the procedure, the biopsy site will be covered with a sterile dressing and a bandage. The dressing should remain in place for three to five days and it is important that you keep the wound and dressing dry. Generally, if stitches were used, they will dissolve and do not need to be removed, but sometimes a stronger type of stitch is used, which will need to be removed. 

If this is the case, you will receive instructions as to which type of stitch you have, and we will give you a letter which tells you when you need to have your stitches removed. Usually this can be done by your GP or practice nurse. We will give you a letter to take to your GP.

If the muscle biopsy has been taken from your leg and you underwent an open muscle biopsy, you should rest for three hours afterwards ideally with your leg raised on a pillow to prevent swelling and complications and to aid healing. If you underwent a needle muscle biopsy, a resting period of 30 minutes will be sufficient.

If possible, on your journey home you should avoid walking and you should be able to keep your leg raised, for example by sitting in the back of a car with your leg resting on a pillow on the seat.

After 24 hours it is important to maintain mobility but try to  avoid a lot of exercise or too much walking for one week. If the biopsy was taken from the arm the main principles of care listed above still apply.

The Neuromuscular Nurse Specialists will be able to advise you further regarding exercise and wound care.

An initial report of the findings from the muscle biopsy is usually available four to eight weeks after the procedure. This initial report is often sufficient but sometimes if additional special tests are required this report will take longer.

A preliminary result of your muscle biopsy may be available sooner, and if appropriate, treatment could commence before a full report is available. Your doctor will contact you to discuss the result either immediately or at an appointment in the clinic.

If you are at all concerned about your wound, please seek medical advice. If you experience excessive pain, swelling, bleeding or drainage from the biopsy site or have any other concerns regarding your wound please see your family doctor (GP) or the practice nurse. If your GP is closed contact your local out of hour’s service that deputises for your GP or go to your local Accident & Emergency department.

The on-call Neurology Registrar covering The National Hospital for Neurology and Neurosurgery can be contacted by the treating Accident & Emergency physician through the switchboard.

For non-urgent enquiries you can contact the Neuromuscular Nurse Specialists. During working hours our answer phone is checked at least twice each day.

Please leave a message with your name and a contact number and we will get back to you as soon as possible.

Centre for Neuromuscular Diseases:

Muscular Dystrophy UK:

0800 652 6352

UCL Hospitals cannot accept responsibility for information provided by other organisations.

The National Hospital for Neurology and Neurosurgery

Queen Square, London, WC1N 3BG

Switchboard: 020 3456 7890


Neuromuscular Disorders Nurse Specialists Direct Lines:       

020 3448 8009

020 3448 8015

020 3448 8682

We are situated between Russell Square and Holborn Tube stations. Buses from main train stations at Euston, Kings Cross and London Waterloo stop on Southampton Row near the hospital and it is a short walk through to the square.


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