A biopsy is a sample of tissue removed by your doctor to make a precise diagnosis. Biopsy procedures can range from a simple sampling of skin under local anesthesia to surgical opening of the chest wall to remove a portion of lung tissue. Biopsies may also be obtained during diagnostic procedures such as endoscopy, colonoscopy, bronchoscopy, and others. Sometimes doctors perform biopsies using a CAT scan or other radiological imaging techniques to help identify the exact area to be sampled and avoid injury to surrounding organs. There are several types of biopsies.