Medical Health Tests Medical Tests Latex Agglutination Test

Definition

This is also called the latex fixation test. It is a laboratory method to find out the presence of certain antibodies and antigens, which are usually produced in the body in response to the rheumatoid factor, or to the rubella factor.

Technique Used

The Latex agglutination technique is used in this test, and it is popular because results can be derived very quickly, in approximately fifteen minutes. The sample acquired for the test is sent to the lab. There it is mixed with tiny latex beads, which have been coated with specific antigens or antibodies. If the suspected bacteria or virus is present, the latex beads tend to clump together (agglutinate).

For example, suppose your health care provider suspects that you have a streptococcus (commonly called 'strep') throat, a throat swab will be taken and sent to the lab. There it will be mixed with the latex beads that have been coated with antigen or antibodies specific to the streptococcus bacteria. If the strep bacteria are present in the sample, it will cause the latex to clump together.

Latex Agglutination Test Samples and Preparation

Various types of body fluids such as urine, blood, cerebrospinal fluid, or serum can be used for the test. The collection techniques and the samples determine the particular kind of antibodies and antigens used.

• Urine samples: You will be given a clean tube or bottle, and will have to provide a sample of urine for testing. You must ensure that no other foreign objects, blood or any other contaminants get into this sample.
• Blood samples: Venipuncture methods will be used. A blood sample will be collected from a vein either from the inside of your elbow, or the back of your hand, by using a sharp needle. The puncture site will be first cleaned with an antiseptic, before inserting the needle. The blood will be drawn and stored in a vial or tube. The puncture site will be tied with a light bandage.
• Cerebrospinal fluid: Cerebrospinal fluid (also known in medical parlance as CSF) is taken by a procedure called a 'spinal tap'. You will be asked to lie down on your side, with your knees pulled up and your chin tucked down. The health care provider, will clean a small portion of your back with antiseptic, apply some local anesthesia to numb the pain, and then insert a spinal needle to draw out a sample of spinal fluid.

Risks

This depends on the method of collection.

• Urine collection carries no risk at all.
• Blood collection involves a slight pricking sensation.
• Collecting the CSF, may be slightly uncomfortable or painful.