What Is a Biopsy?

A biopsy is a medical procedure to remove a small piece of tissue or sample of cells from the body for physical (through a microscope) or chemical examination.

A biopsy can be conducted on any area of the body, and is the only diagnostic technique able to definitively identify cancerous tissue and cells.

Why Are Biopsies Conducted?

Biopsies are usually conducted to identify cancerous tissue, but they can also test for other health issues.

For example:

• Liver biopsies can diagnose hepatitis C, cirrhosis (liver scarring), and infections
• Kidney biopsies can examine the condition of a kidney with kidney failure or inflammation
• Nerve biopsies can examine nerve damage and inflammatory nerve conditions
• Muscle biopsies can diagnose infections and defects of the muscles, as well as diseases of connective tissues and blood vessels
• Skin biopsies can test for changes in skin conditions, such as moles
• Biopsies of the gastrointestinal tract may detect suspected inflammatory bowel conditions, including Crohn’s disease and ulcerative colitis

Types of Biopsy Procedures

Biopsy procedures can be differentiated into a few broad categories: needle, open, closed, and skin.

Needle biopsies, sometimes called percutaneous biopsies, remove tissue or cells using needle devices, which differ depending on the type and amount of sample needed.

Fine-needle aspiration biopsies use a very thin needle — smaller than those used to draw blood — attached to a syringe, according to the Mayo Clinic.

It can remove a small amount of fluid and tiny pieces of tissue, and sometimes must be inserted numerous times to acquire enough samples for testing.

Core needle biopsies use a needle with a larger “core,” or hollow space, which is able to draw out an entire column of tissue, says the American Cancer Society.

They’re generally done with local anesthesia, and are sometimes combined with a vacuum-powered instrument that uses pressure to pull out more tissue.

To take deep tissue samples, needle biopsies are guided with imaging techniques, such as ultrasounds, computerized tomography (CT) scans, and magnetic resonance imaging (MRI) scans.

Open biopsies remove tissue using open surgery, or incisions into the skin and body. They’re conducted under anesthesia, according to Mount Sinai.

Closed biopsies, or endoscopic biopsies, take tissue samples with endoscopes, which are thin, flexible tubes with a light and camera at the end.

The endoscopes may be inserted into the mouth, rectum, or urinary tract, or through a small incision (smaller than that of an open biopsy).

Special cutting tools are passed through the endoscope to collect tissue samples.

Skin (cutaneous) biopsies remove cells from the surface of the body, such as by scraping the skin, cutting out small or large areas of skin, or using an instrument to punch a hole through the skin, according to the American Academy of Dermatology.