Complete blood count

A complete blood count (CBC) is a blood panel requested by a doctor or other medical professional that gives information about the cells in a patient's blood, such as the cell count for each blood cell type and the concentrations of hemoglobin. A scientist or lab technician performs the requested testing and provides the requesting medical professional with the results of the CBC. A complete blood count (CBC) is a blood panel requested by a doctor or other medical professional that gives information about the cells in a patient's blood, such as the cell count for each blood cell type and the concentrations of hemoglobin. A scientist or lab technician performs the requested testing and provides the requesting medical professional with the results of the CBC. Blood counts of various types have been used for clinical purposes since the nineteenth century. Automated equipment to carry out complete blood counts was developed in the 1950s and 1960s. Most blood counts today include a CBC count (i.e.: complete blood count) and leukocyte differential count (LDC) that gives the percentage of each WBC type, such as neutrophils, eosinophils, basophils, monocytes, and lymphocytes. The cells that circulate in the bloodstream are generally divided into three types: white blood cells (leukocytes), red blood cells (erythrocytes), and platelets (thrombocytes). Abnormally high or low counts may indicate the presence of many forms of disease, and hence blood counts are among the most commonly performed blood tests in medicine, as they can provide an overview of a patient's general health status. A CBC is routinely performed during annual physical examinations in some jurisdictions. Complete blood counts are done to monitor overall health, to screen for some diseases, to confirm a diagnosis of some medical conditions, to monitor a medical condition, and to monitor changes in the body caused by medical treatments. For patients who need blood transfusion, a blood count may be used to get data which would help plan an amount of treatment. In such cases, the person should have only one blood count for the day, and the transfusion of red blood cells or platelets should be planned based on that. Multiple blood draws and counts throughout the day are an excessive use of phlebotomy and can lead to unnecessary additional transfusions, and the extra unnecessary treatment would be outside of medical guidelines. A phlebotomist collects the sample through venipuncture, drawing the blood into a test tube containing an anticoagulant (EDTA, sometimes citrate) to stop it from clotting. The sample is then transported to a laboratory. Sometimes the sample is drawn off a finger prick using a Pasteur pipette for immediate processing by an automated counter. Before the advent of automated hematology analyzers, CBCs were performed manually, by counting cells in a diluted sample of blood on a device called a hemocytometer, and by viewing a slide prepared with a sample of the patient's blood (a blood film, or peripheral smear) under a microscope. However, manual blood cell counts are becoming less common, and instead this process is generally performed by the use of an automated analyzer. Typically, analysis begins when a well mixed whole blood sample is placed on a rack in the analyzer. The instrument utilizes flow cells, photometers and apertures in order to analyze different elements in the blood. The cell counting component counts the numbers and types of different cells within the blood. A special photometer called a hemoglobinometer measures the amount of hemoglobin. This is done by adding a diluent that lyses the red blood cells which is then pumped into a spectro-photometric measuring cuvette. The change in color of the lysate equates to the hemoglobin content of the blood. This information can be very helpful to a physician who, for example, is trying to identify the cause of a patient's anemia. The results are printed out or sent to a computer for review. Blood cell counting occurs by flow cytometry when a very small amount of the specimen is aspirated, diluted and passes through an aperture and a laser flow cell. Sensors count and identify the number of cells passing through the aperture. The two main types sensors used are laser light detectors and electrical impedance. The instrument determines the type of blood cell by analyzing data about the size and aspects of light as they pass through the cells. Some instruments measuring different characteristics of the cells in order to categorize them.