Biopsy

A diagnostic test in which a small amount of tissue or cells are removed from the body for microscopic examination. It is an accurate method of diagnosing many illnesses, including cancer. Microscopic examination of tissue ( histology) or of cells ( cytology) usually gives a correct diagnosis. There are several types of biopsy. In excisional biopsy, the whole abnormal area is removed for study. Incisional biopsy involves cutting away a small sample of skin or muscle for analysis. In a needle biopsy, a needle is inserted through the skin and into the organ or tumour to be investigated. Aspiration biopsy uses a needle and syringe to remove cells from a solid lump. Guided biopsy uses ultrasound scanning or CT scanning to locate the area of tissue to be biopsied and to follow the progress of the needle. In endoscopic biopsy, an endoscope is passed into the organ to be investigated and an attachment is used to take a sample from the lining of accessible hollow organs and structures, such as the lungs, stomach, colon, and bladder. In an open biopsy, a surgeon opens a body cavity to reveal a diseased organ or tumour and removes a sample of tissue. Prompt analysis, in some cases by frozen section, can enable the surgeon to decide whether to remove the entire diseased area immediately. Biopsy samples are analysed by staining, in which dyes are used to to show up structures or identify constituents such as antibodies or enzymes. A tissue sample may be tested with specific antibodies in the investigation of infection and inflammation. In some cases, a tissue culture may be required.