This involves sampling a tiny piece of tissue to examine it under the microscope to establish a precise diagnosis.
When an area of the body differs from an expected appearance on imaging (such as X-ray, ultrasound, CT) it is not always possible to give an exact diagnosis, so a biopsy may be used to sample the tissue - for example in the breast, thyroid and liver. Ultrasound, CT or MRI is used by the Radiologist to accurately guide to the area to be sampled, a biopsy is performed using a hollow needle, and the specimen sent for laboratory testing.