Alternative Names cytomegalovirus antibody test, CMV blood test, CMV serology
Definition This test detects the presence of antibodies in the blood to cytomegalovirus (CMV).
The body produces antibodies to defend against bacteria, viruses and other harmful foreign particles. The body produces large amounts of antibodies during infections. A person's blood can be analysed for particular antibodies. Their presence indicates that the person has been exposed to that infection-causing particle.
Who is a candidate for the test? The CMV test is performed when a doctor suspects a CMV infection may be present. CMV usually only causes serious infections in people who have a weakened immune system. For example, people who take medications to suppress the immune system, such as after an organ transplant, and people with cancer or AIDS usually have weakened immune systems.
How is the test performed? In order to test for CMV antibodies, a blood sample is needed. The blood is usually drawn from a vein in the forearm or the hand. First, the skin over the vein is cleaned with an antiseptic. Next, a strong rubber tube, or tourniquet is wrapped around the upper arm. This enlarges the veins in the lower arm by restricting blood flow. A thin needle is gently inserted into a vein and the tourniquet is removed. Blood flows from the vein through the needle and is collected in a syringe or vial. The sample is sent to the laboratory to be analysed. After the needle is withdrawn, the puncture site is covered for a short time to prevent bleeding.
What is involved in preparation for the test? No preparation is required for this test.
What do the test results mean? In people who have not been infected with CMV, there are no antibodies to CMV in the blood. This is considered a negative test.
If a person has antibodies against CMV, the test is positive. This means that a person has been infected with CMV in the past. Once a person has had a CMV infection, the virus generally stays in the body for life. When the immune system becomes weak, the infection can sometimes return. If the infection returns, strong antibiotics may be needed to treat it.
Author: Reviewer: eknowhow Medical Review Panel Editor: Dr John Hearne Last Updated: 27/02/2005 Contributors Potential conflict of interest information for reviewers available on request
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