What happens during a biopsy?

If a doctor feels something unusual during a physical examination (palpation), analyzing a sample of tissue can help to find out what it is. Biopsies might also be done to find out more if imaging techniques such as ultrasounds or x-rays show abnormal areas of tissue. Then chronically inflamed tissue can be diagnosed or cancer ruled out, for example. Samples of tissue can be taken from easily accessible parts of the body as well as from many internal organs.

Common biopsies include breast, prostate gland, skin and cervical biopsies. But tissue samples may also be taken to find out more about abnormal tissue in the liver, thyroid, stomach or muscles.

Biopsies are relatively simple procedures that can often be done without having to stay overnight in hospital. The length of the procedure will depend on the part of the body or organ in question and which technique is used.

The doctor will first decide which exact area the tissue should be taken from. For internal organs, this is done with the help of imaging techniques such as ultrasound, magnetic resonance imaging (MRI) or computed tomography (CT) scans. In endoscopy, the tissue sample can be taken during the examination – for example, from the stomach, colon or lungs.

If a tissue sample is removed through a cut in the skin, the skin is disinfected first. Usually just a local anesthetic is needed for a biopsy, depending on the size of the instrument to be used. After an outpatient biopsy has been completed, the wound is covered with a wound dressing. Antibiotics are sometimes prescribed to prevent infection, for instance after a prostate biopsy.

If the procedure involves an internal organ, such as the liver or kidney, or if the person has poor general health, a hospital stay is often needed. Several biopsies may be needed if the disease is at an advanced stage or if the organ is difficult to reach, such as the prostate gland.

There are two main types of biopsies:

• Incisional biopsies: Only a part of the abnormal tissue is removed.
• Excisional biopsies: The entire abnormal area is cut out.

Excisional biopsies are mostly done when skin cancer is suspected, but they are also done when looking at colon polyps (which may turn into bowel cancer). The amount of tissue taken depends on the organ in question, the size of the abnormal area, and the type of tissue.

If only a small sample is needed, a needle biopsy is typically done. Here the doctor puts a very thin hollow needle into the tissue. Depending on the diameter of the needle, samples of either individual cells (fine needle biopsies) or small pieces of tissue (core needle biopsies) can be taken. In an open biopsy, by contrast, surgery is done to expose and remove the tissue.

The tissue sample is examined in a laboratory using a microscope. Dyes can be used to see certain cells or enzymes that may be signs of disease. If cancer is discovered, the tissue sample may also be used to find out what type of tumor it is and how much it has spread through the tissue.

A biopsy may cause bleeding or bruising. A wound infection or damage to nearby tissue are also possible.

Some people worry that the biopsy may accidentally allow cancer cells to spread to healthy tissue and other parts of the body. But experts currently agree that this is unlikely to happen.