A biopsy involves removing a small part of an organ or tissue in order to perform medical tests. The biopsy can be done using a needle, smear, or endoscopy on any type of human tissue. The biopsy enables the establishment or confirmation of a reliable diagnosis of a suspected disorder by analyzing the sample under a microscope for example. It is widely used in oncology, but also in genetics and neurology. Some diseases cannot be diagnosed with certainty only by a biopsy.