A biopsy is a diagnostic procedure where a tissue or cell sample is removed and then examined under a microscope. Biopsies are done either in the doctor’s office or in the hospital. The sample is then sent to a lab, where a pathologist analyzes it and tests it for abnormalities that may help the medical team make a diagnosis or better understand a diagnosed condition.

Biopsies are commonly used to determine whether a tumor or growth is cancerous or non-cancerous (benign), to analyze the blood cells in the bone marrow, or to identify tissue changes that may indicate a non-cancerous disease or condition like inflammatory bowel disease.

The type of biopsy used—and whether local or general anesthetic is required—will depend on the location of the tissue, and how big a sample is needed.

For example, with skin lesions a punch biopsy or shave biopsy can be performed quickly in the doctor’s office with only local anesthesia. Fine needle aspiration biopsy is usually done in an outpatient setting, where a thin needle and syringe are inserted to remove small tumor samples, such as in thyroid tumors or breast tumors, or to see if cancer has spread to lymph nodes. Excisional biopsy (also called incisional biopsy) is used to remove larger samples or partial or full tumors and requires an incision. Biopsies may also be performed endoscopically, which often requires general anesthesia and is part of a larger diagnostic procedure to examine a specific organ or area of the body.