Cytomegalovirus test (CMV)
What cytomegalovirus is
Cytomegalovirus belongs to the herpes virus family — the same group as the viruses that cause chickenpox, shingles and infectious mononucleosis. MedlinePlus states that once a person is infected, the CMV virus stays in the body for life in an inactive state and can become active again if immunity falls or after severe stress. Most healthy people do not even notice the infection, or feel only mild, flu-like symptoms — swollen lymph nodes, a sore throat, fever, tiredness, weakness, muscle aches or headache. A CMV blood test establishes whether a person has ever encountered this virus, but on its own it does not show whether the infection is active now, was in the past, or is a recently reactivated infection — additional tests are needed for that. A CMV test is especially important during pregnancy and for newborns, because the virus can be dangerous to the fetus, and also for people whose immunity is weakened (for example, by HIV infection or cancer treatment) or after an organ transplant.
The result: positive or negative
A CMV blood test shows whether a person has ever been infected with the virus. The answer is positive or negative — there is no numeric reference range to compare a result against.
| What the CMV test shows | What it does not show |
|---|---|
| Whether a person has ever been infected with cytomegalovirus | Whether the infection is active now, was in the past, or has recently become active again (reactivation) — additional tests are needed for that |
When a CMV test is done
- Pregnant women in whom an active CMV infection is suspected — with swollen lymph nodes, a sore throat, fever, tiredness, weakness or muscle aches (MedlinePlus)
- People with weakened immunity (for example, HIV infection, cancer) — when they have similar symptoms (MedlinePlus)
- Newborns in whom possible signs of infection are noticed — jaundice, low birth weight, a small head circumference, hearing or vision problems, seizures or a rash (MedlinePlus)
- Organ transplant recipients (MedlinePlus)
- Newborns with a very low birth weight, or born prematurely (MedlinePlus)
- As part of the TORCH panel during pregnancy or for newborns — together with tests for toxoplasmosis, rubella and herpes simplex virus (MedlinePlus)
How to prepare
- Most CMV blood tests need no special preparation (MedlinePlus)
- Some related tests do require preparation: before a lumbar puncture you may need to empty your bladder, before a biopsy — not to eat (MedlinePlus)
- Amniocentesis early in pregnancy may require a full bladder; later in pregnancy the opposite — an empty one (MedlinePlus)
- For newborn testing, a saliva sample is taken within the first three weeks after birth, and urine — with a special bag (MedlinePlus)
What a positive result means
A positive CMV test result means that the person has been infected with cytomegalovirus at some point in their life. MedlinePlus stresses that the test itself does not show whether the infection is active now, was in the past, or has recently become active again — additional tests are needed for that. Once the virus has entered the body, it stays there for life in an inactive state.
- A CMV infection in the past, often without the person even noticing it (MedlinePlus)
- A CMV infection that is active at the moment (MedlinePlus)
- Reactivation of an infection acquired earlier — for example, when immunity falls or after stress (MedlinePlus)
Possible signs
- Swollen lymph nodes (MedlinePlus)
- A sore throat (MedlinePlus)
- Fever (MedlinePlus)
- Tiredness and weakness (MedlinePlus)
- Muscle aches or headache (MedlinePlus)
What to discuss with a doctor
- Whether additional tests are needed to establish if the infection is active, in the past, or reactivated
- For pregnant women — whether amniocentesis is needed to assess the condition of the fetus
- For newborns with a positive result — whether assessment and follow-up after birth are needed
- For people with weakened immunity — how to monitor for possible reactivation
Full site in Lithuanian: proactiva.app
Frequently asked questions
›What is cytomegalovirus (CMV)?
CMV is a herpes-family virus, similar to the viruses that cause chickenpox or mononucleosis. According to MedlinePlus, once a person is infected the virus stays in the body for life, most often in an inactive state, and it can become active again if immunity weakens.
›What does a positive CMV test result mean?
A positive result means that the person has been infected with CMV at some point in their life. MedlinePlus notes that the test itself does not show whether the infection is active now, was in the past, or has recently become active again — additional tests are needed for that.
›Why does a CMV test matter during pregnancy?
MedlinePlus states that an active CMV infection during pregnancy can be dangerous to the fetus, so for pregnant women with symptoms (fever, swollen lymph nodes, tiredness) the test may be recommended. Amniocentesis is also carried out if needed.
›How is a CMV test done in newborns?
MedlinePlus describes a saliva sample being taken within the first three weeks after birth for newborn CMV testing, or a urine sample collected with a special bag. The test is done when possible signs of infection are noticed — jaundice, low birth weight, hearing or vision problems.
›Does a CMV test need any special preparation?
Most CMV blood tests need no special preparation, according to MedlinePlus. Some related tests (a lumbar puncture, a biopsy, amniocentesis) have their own preparation requirements.
›What is the TORCH panel?
TORCH is a group of tests covering toxoplasmosis, rubella, cytomegalovirus and herpes simplex virus. MedlinePlus states that it is often done during pregnancy or for newborns, to check for these infections.
›Is a CMV test risky?
MedlinePlus notes that blood, sputum or newborn saliva/urine tests carry minimal risk. A lumbar puncture can cause back pain or headache, and amniocentesis can — rarely — cause tingling, cramping or fluid leakage.
Sources
- MedlinePlus: Cytomegalovirus (CMV) Tests — 2026-09-07
Related markers
This site is not an emergency service. If severe chest or head pain, breathlessness, confusion, difficulty speaking, heavy bleeding or another acute problem has come on suddenly — do not wait for tests, call 112.
This information is not a diagnosis and does not replace a consultation with a doctor. Reference ranges depend on the laboratory, your age and sex — always compare your result with the range printed on your own report.