What happens during a biopsy?

A biopsy (taking a tissue sample) is one of the most commonly used medical tests. Tissue samples can be analyzed in order to find out, for instance, whether a suspicious lump is harmless or dangerous. The doctor removes a small sample of tissue and sends it to a laboratory to be examined under a microscope. The tissue sample can often be removed in an outpatient setting.

When are biopsies necessary?

If a doctor feels something unusual during a physical examination (palpation), analyzing a sample of tissue can help find out what it is. Biopsies might also be necessary for further clarification if imaging techniques such as ultrasounds or x-rays reveal abnormal areas of tissue. Then chronically inflamed tissue can be detected 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 from the liver, thyroidstomach or muscles.

What exactly do biopsies involve?

Biopsies are relatively simple procedures that can often be done without having to stay overnight in hospital. Exactly how long the procedure takes and what kind of doctor carries it out will depend on the part of the body or organ in question and which technique is chosen.

The doctor will first decide which exact area of the body the tissue should be taken from. For internal organs, this is done with the help of imaging techniques such as ultrasound, magnetic resonance imaging or computed tomography scans. Endoscopy can be used to view the tissue as the sample is being taken - for example, from the stomach, large bowel or lungs.

Non-internal tissue samples are taken after the skin has been disinfected. 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, as is the case following 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 required. Multiple biopsies may be needed if the disease is at an advanced stage or if the organ is difficult to access, such as the prostate gland. 

Illustration: Performing a biopsy - as described in the articlePerforming a biopsy

What different types of biopsies are there?

A general difference is made between biopsies that involve removing only a part of the tissue believed to be abnormal (incisional biopsy) and those where the entire abnormal area is cut out (excisional biopsy). The latter is used mostly in the case of suspected skin cancer or colon polyps, a possible precancerous condition of the bowel. The amount of tissue sampled depends on the organ in question, the size of the possibly abnormal area and the type of tissue.

A needle biopsy is typically used if only a small sample is needed. The doctor puts a very thin hollow needle into the tissue to be examined. 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. An open biopsy, by contrast, is done by exposing and removing the tissue.

What can a biopsy find?

The tissue sample is then 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 found, the tissue sample may also be used to tell what type of tumor was discovered and how much it has spread through the tissue.

What possible complications are there?

Bleeding or bruising may follow a biopsy. Infection of the wound or damage to neighboring tissue are also possible.

Some people worry that the biopsy may accidentally allow cancer cells to move to healthy tissue and develop new tumors there, but this is unlikely according to the current state of medical knowledge.