CMV serology testDefinition:
The CMV serology test determines the presence of antibodies to cytomegalovirus (CMV) in the blood.
CMV antibody tests
How the test is performed:
Blood is typically drawn from a vein, usually from the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.
Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.
In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding.
Serology studies the fluid portion of blood (serum) for its antibody content. Serology tests are often repeated a few weeks after the first sample. There are several serology techniques that can be used, depending on the suspected antibodies.
How to prepare for the test:
There is no special preparation for the test.
How the test will feel:
When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.
Why the test is performed:
The test is performed to detect current active CMV infection, or past CMV infection in people who are at risk for reactivation of infection (such as organ transplant recipients and people with a suppressed immune system). The test may also be performed to detect CMV infection in newborns.
People who have never been infected with CMV have no detectable antibodies to CMV.
Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.
What abnormal results mean:
The presence of antibodies to CMV indicates a current or past infection with CMV. If the number of antibodies rises over a few weeks, it may mean that you have an acute infection.
Chronic CMV infection (in which the antibody count stays about the same over time) can reactivate in a person with a suppressed immune system.
What the risks are:
Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight but may include:
- Excessive bleeding
- Fainting or feeling light-headed
- Hematoma (blood accumulating under the skin)
- Infection (a slight risk any time the skin is broken)
To detect a blood or organ infection with CMV, the health care provider can test for the presence of CMV itself in the blood or a specific organ.
Drew WL. Cytomegalovirus. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier;2007:chap 399.