Blood is drawn from a vein, usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and an elastic band or blood pressure cuff is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the band to fill with blood and bulge. A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the tourniquet is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.
Infant or young child:
The area is cleaned with antiseptic and stuck with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, on a test strip, or into a small container. A bandage may be applied to the puncture site if there is any continued bleeding.
Serology refers to the study of serum for its antibody content. An antibody defends the body against bacteria, viruses, fungus, or other foreign bodies (antigens). Certain microbial cells stimulate the body to produce these antibodies during an active infection. Antibody production increases during the course of infection.
In the early stage of an illness, little or no antibody may be detected. For this reason, serology tests are often repeated 2 to 4 weeks after the initial sample.
In the laboratory, the antibodies react with antigens in specific ways that can confirm the identity of a specific microorganism. There are several serology techniques that can be used depending on the suspected antibodies. Serology techniques include agglutination, precipitation, complement-fixation, fluorescent antibodies, and others.
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