Ordering Recommendation

Aid in the diagnosis of cytomegalovirus (CMV) infection during pregnancy after initial testing for CMV IgM and IgG has been performed.

New York DOH Approval Status

This test is New York state approved.

Specimen Required

Patient Preparation

Serum separator tube (SST).

Specimen Preparation

Separate serum from cells ASAP or within 2 hours of collection. Transfer 0.5 mL serum to an ARUP Standard Transport Tube. (Min: 0.15 mL)

Storage/Transport Temperature


Unacceptable Conditions

After separation from cells: Ambient: 48 hours; Refrigerated: 2 weeks; Frozen: 1 year


Semi-Quantitative Enzyme-Linked Immunosorbent Assay




1-8 days

Reference Interval

0.50 Index or less: Low Avidity
0.51-0.59 Index: Intermediate Avidity
0.60 Index or greater: High Avidity

Interpretive Data

Identifying CMV infections in pregnant women during the first trimester is of significant importance for clinical care. Acute infection is typically characterized by increased CMV-specific IgM and IgG antibodies. However, CMV IgM antibodies may persist for several months or even years after initial infection, which limits their utility in the accurate diagnosis of recent CMV infection. CMV IgM antibodies can also be detected during viral reactivation, thus complicating the diagnosis of a recent primary infection. Therefore, measuring IgG antibody avidity to CMV antigens can aid in discriminating recent from prior CMV infections. Index values of 0.5 or less generally indicate recent infection (within the previous 3 to 4 months). However low avidity values cannot exclude the possibility of persistent IgG antibodies with low avidity. Index values of 0.6 or greater indicate an infection occurring more than 3 months prior to testing. Because IgG avidity testing for CMV after the first trimester is not easily interpreted, detection of high avidity CMV IgG antibodies during the first trimester (12 to 16 weeks gestation) helps exclude a diagnosis of an acute CMV infection post-conception.

This test was developed and its performance characteristics determined by ARUP Laboratories. It has not been cleared or approved by the US Food and Drug Administration. This test was performed in a CLIA certified laboratory and is intended for clinical purposes.

Compliance Category

Laboratory Developed Test (LDT)


Hotline History


CPT Codes



Component Test Code* Component Chart Name LOINC
2011814 CMV IgG Ab Avidity 52984-2
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.


Cytomegalovirus Antibody, IgG Avidity