Gastro Enterology => Biopsy
Biopsy, surgical removal of living body tissue for study and diagnosis with a microscope. Biopsies are performed on organs to analyze the cause and nature of disease, and on tumors, or abnormal tissue growths, to determine if they are a type of cancer. For patients diagnosed with certain diseases, follow-up biopsies are used to study the effectiveness of a chosen course of medical treatment. Biopsies are vital in diagnosing and monitoring a wide range of illnesses, including muscular dystrophy, characterized by gradual wasting away of skeletal muscle, and Crohn's disease, the chronic inflammation of the intestines.
An external biopsy specimen is taken by cutting or scraping a piece of tissue from an affected area of skin. When a sample is needed from an area well below the surface of the skin, the procedure is called internal biopsy, and viewing techniques such as ultrasound or computer axial tomography are often used to help the physician guide a hollow needle to the exact location.
In a procedure called aspiration biopsy, a needle is attached to a hypodermic syringe. A tissue sample is collected in the barrel of the syringe by using the suction that is created when the plunger of the syringe is pulled out. In a needle biopsy, the tissue sample is collected by rotating the needle, trapping a small but sufficient amount of tissue within the needle itself. In a punch biopsy, a sharp-edged instrument is used to recover a round piece of tissue from a specific depth below the skin.
Amniocentesis is a form of aspiration biopsy in which a very thin needle is used to remove sample cells from the amniotic fluid that surrounds a fetus in the uterus to study the genetic information they contain. The cell sample is normally taken during the fourth month of pregnancy, and the results reveal the gender of the fetus and also detect genetic abnormalities like Down syndrome.
The endoscope, a cameralike tube with a light, enables physicians to see inside hollow organs like the stomach and bladder, and aids in the procedure of internal biopsy. A tiny knife or scissorslike instrument is attached to the endoscope and is used to cut away sample tissue. By using this form of endoscopic biopsy, the physician can both view and remove the tissue of interest.
Open biopsy is the most invasive of biopsy procedures, involving the surgical opening of a body cavity in order to remove a tissue sample. Once the sample is taken, the surgical procedure is temporarily halted while the suspect tissue is quick-frozen and subjected to microscopic examination. The high magnification of an electron microscope is sometimes used by lab technicians to guarantee a proper diagnosis. If the biopsy confirms the existence of cancer, the completion of the operation may involve the removal of the tumor or even of an entire organ, such as a cancerous lung.
If the physician has no immediate need to learn the results of an open biopsy, then the tissue sample may be prepared for examination at a later time by fixing and preserving it chemically. Chemical fixation, which may take one or more days, involves removing water and fats from the specimen and embedding the tissue sample in paraffin. It is then cut into ultrathin slices and stained before it is examined under a microscope. Again, an electronic microscope may be used to confirm the results of the biopsy.