In muscle biopsy, a tissue sample is extracted from a muscle and sent to a laboratory for microscopic examination. Several techniques may be used, including needle biopsy, which uses a long, thin needle to withdraw a specimen, and, less often, open biopsy, which accesses the muscle surgically through a small incision.

Purpose of the Muscle Biopsy

  • To diagnose some muscle diseases, including muscular dystrophy (progressive atrophy of muscles) and myositis (inflammation of the muscles)
  • To help distinguish between nerve and muscle disorders
  • To diagnose certain diseases of the blood vessels and connective tissues, such as generalized vasculitis (inflammation of blood vessels)
  • To diagnose infections that affect the muscles, such as trichinosis or toxoplasmosis

Who Performs It

  • A physician

Special Concerns

  • Preliminary tests, including laboratory studies and electromyography, should be done first to determine if a muscle biopsy is necessary and to identify an appropriate biopsy site. The biopsy is usually performed only to confirm a suspected diagnosis.
  • Open biopsy is typically done only in cases where a larger piece of tissue is needed to confirm a diagnosis, or when the condition is believed to be localized or found in patches.
  • Muscle biopsy should not be performed on sites that have recently undergone EMG or areas affected by preexisting conditions such as nerve compression.

Before the Muscle Biopsy

  • You may be asked to wear loose clothes or to remove your clothes and put on a hospital gown, depending on the biopsy site.
  • Drink, but do not eat, after midnight the night before your muscle biopsy if you are set to be sedated. Do not eat or drink before you have your procedure.
  • Notify your physician if you have any sensitivities or allergies, including to any drugs (including anesthesia) or materials used in medical procedures, such as tapes and latex.
  • Be sure to inform your physician of any medications or supplements you are taking.
  • Tell your doctor if you are or think that you could be pregnant.

What You Experience

Needle biopsy:

  • You will be positioned differently according to the selected procedure site.
  • The skin at the biopsy site is cleansed with an antiseptic solution, and a local anesthetic is injected to numb the area. You may feel a brief stinging sensation for a few seconds after the anesthetic is injected, and you may still feel pressure or a pulling sensation when the biopsy is taken.
  • The doctor inserts a thin needle through the skin into the muscle, and withdraws a small plug of tissue. Sometimes several samples are taken.
  • Pressure is placed on the needle insertion site until bleeding has stopped, and a small bandage is applied.
  • The procedure usually takes about 1 hour.

Open biopsy:

  • You will be positioned differently according to the selected procedure site.
  • The skin at the biopsy site is shaved and cleansed with an antiseptic, and a local anesthetic is injected to numb the area (you may still experience brief discomfort when the biopsy is taken). You may feel a brief stinging sensation for a few seconds after the anesthetic is injected.
  • A small incision is made with a scalpel, the skin is pulled back, and surgical scissors are used to extract several small pieces of muscle tissue.
  • The incision is stitched closed and covered with a sterile dressing.
  • An open muscle biopsy takes about 1 hour to perform.

Risks and Complications

  • Bruising, discomfort, bleeding and infection can occur at the site of the biopsy.
  • The most common aftereffect is soreness. In addition, after a needle biopsy, swelling or discoloration may develop due to collection of blood under the skin (hematoma) at the needle insertion site; this is harmless, but may cause some discomfort. Serious complications are rare.

After the Muscle Biopsy

  • The biopsy site may remain sore for about 1 week. You may be given pain-relieving medication to allay any discomfort.
  • For a large hematoma that causes swelling and discomfort, apply ice initially; after 24 hours, use warm, moist compresses to help dissolve the clotted blood.
  • Resume your normal activities when it is comfortable to do so.


  • A pathologist examines the muscle specimens under a microscope for the presence of muscle fiber abnormalities or unusual cells. In some cases, chemical analysis may also be done, for example, to examine the activity of various enzymes responsible for producing energy in the muscle.
  • In many cases, a definitive diagnosis can be made and treatment will be initiated.
  • A negative biopsy does not exclude the presence of a suspected disease—for example, if the biopsy site was not selected properly. In such cases, the procedure may need to be repeated.


The Johns Hopkins Consumer Guide to Medical Tests

Simeon Margolis, M.D., Ph.D., Medical Editor

Updated by Remedy Health Media

Publication Review By: the Editorial Staff at

Published: 12 Jan 2012

Last Modified: 12 Jan 2012