A muscle biopsy is a sample of muscle tissue taken for laboratory analysis. Biopsies can be requested for a number of different reasons and the time it takes to get results varies, depending on the type of biopsy requested and how busy things are at the pathology lab. Generally, patients can get a response in less than a week and their doctors will tell them if the testing is expected to take longer. Patients can also request a phone call, even if the results are negative, so they know the sample has been processed.
To collect a sample for muscle biopsy, there are several options. One is a needle biopsy, where a hollow needle is inserted and used to pull out a small sample of tissue. Surgical biopsy is another method. In this technique, anesthesia is used and a surgeon makes a small incision to access the muscle and pull out a sample. If a patient is already in surgery and a surgeon is concerned about changes to the tissue, a sample can be collected for biopsy while the patient is already on the table.
Muscle biopsies can be used to check for signs of infectious organisms like parasites that sometimes set up camp in the muscles, as well as to look for indicators of connective tissue disorders. Some health problems cause physical changes in the muscles such as damage to the cells, and a muscle biopsy will be used to identify those conditions in a patient. Muscle biopsies are also used to confirm that a surgeon has debrided infected or dead tissue all the way to the margins, not leaving anything behind, in which case a pathologist stands by during surgery to look at samples and provide an immediate response.
After a muscle biopsy, patients usually experience soreness at the site, and they may notice some bruising. Pain medications may be provided after surgery and patients are usually advised to rest the muscle to allow it to recover. The muscle tissue will rebuild itself over time, although if a very large chunk of muscle is removed, the patient may be left with a mark or divot showing where the tissue used to be.
Sometimes biopsy results are negative, indicating no trace of a problem. Other results may be positive for an organism or chemical compound of concern, or show signs of physical damage like tearing of the muscle fibers. Inconclusive results are returned when the sample was not large enough or when there were problems with the analysis, and it is impossible to return a result with confidence. Doctors try to take appropriately sized samples and handle them correctly to avoid situations where they need to go back in for a second muscle biopsy to resolve an inconclusive result.
