Cytomegalovirus (CMV) is a common virus. According to the Centers for Disease Control and Prevention (CDC), it infects between 50 to 80 percent of all adults by the time they reach 40 years old. Usually, CMV doesn’t cause any symptoms or health problems. It will remain in your body in a latent form. This means the virus is present but not causing any symptoms. If you develop health problems that weaken your immune system, CMV may become active. It can then become an acute infection.
Your doctor can use the CMV serology test to check your blood for antibodies to CMV. If you’ve been infected with CMV, you will have elevated CMV antibody levels.
Your doctor can order a CMV test to learn if you currently have an active CMV infection or have had one in the past. They can also use it to learn if treatment for an active CMV infection is working.
Your doctor may order the test if you have a compromised immune system, or you’re pregnant, and you have symptoms such as:
- sore throat
- swelling in your lymph nodes
- muscle aches
Viruses that cause the flu or mononucleosis, such as the Epstein-Barr virus, can also cause these symptoms.
Your doctor may order a CMV test for your newborn baby, if they have the following symptoms:
- yellowing of their skin or eyes, known as jaundice
- enlarged spleen or liver
- hearing or vision problems
- delayed development
The test is also used as a screening tool for:
- people seeking an organ transplant
- organ donors
- egg and sperm donors
The CMV serology test is performed using a blood sample. A nurse or lab technician in a clinical setting usually takes this sample. Using a small needle, they collect blood from a vein in your arm or hand. Then they send your blood sample to a lab for analysis. Your doctor will explain your results when they become available.
No preparation is needed for this test.
The risks of a CMV test are minimal. You may experience some discomfort when your blood sample is drawn. You may have pain at the puncture site during or after the test.
Other potential risks of a blood draw include:
- difficulty obtaining a sample, resulting in multiple needle sticks
- excessive bleeding at the needle site
- fainting as a result of blood loss
- accumulation of blood under your skin, known as a hematoma
- infection at the puncture site
A negative test means you have no CMV antibodies in your blood. This suggests you’ve never been infected with CMV. It may also indicate that you’re immunocompromised, which means you have a weakened immune system, and it can’t make antibodies against the virus.
Low levels of CMV antibodies indicate exposure to CMV. However, they don’t reveal when you were infected. Your doctor will need to review your results in conjunction with your symptoms to determine if you have an active infection.
When the test is used to monitor treatment efficacy, your doctor will look for a decline in the amount of CMV antibodies in your blood over time. Treatment lowers viral levels, so your antibody levels should decline as well if the treatment is working.
The CMV test is a low-risk procedure that involves a simple blood draw. You don’t need to take any special steps to prepare for it. Your doctor can use it to learn if you have an active CMV infection or have had one in the past. They can also use it to monitor your progress if you’ve received treatment for a CMV infection.