Elecsys® CMV IgG

Immunoassay for the quantitative determination of IgG-antibodies against CMV

Elecsys® CMV IgG
Immunoassay for the quantitative determination of IgG-antibodies against CMV

Cytomegalovirus (CMV) is a herpes virus ubiquitous in humans, and it is the leading infectious cause of congenital malformations.1 Anti-CMV IgG and IgM reactive samples may indicate an acute, recent or reactivated infection.

Since fetal symptomatic congenital infection is mostly due to intrauterine transmission following primary maternal infection, differential diagnosis of primary versus recurrent infection, unspecific IgM or persistence of CMV-specific IgM antibody is crucial for the management of the pregnancy.2 Antibodies produced at an early stage during primary response have lower antigen avidity than those produced at a later stage.2

There is currently no generally accepted therapy available3, but recent scientific evidences showed that antiviral medication can reduce the risk of vertical transmission, making the screening and treatment of cytomegalovirus in pregnancy to protect the unborn baby's health finally an available option4. The diagnosis of CMV infection usually starts with the detection of anti-CMV IgG and IgM antibodies. Seroconversion in CMV IgG shows a recent infection. The detection of CMV IgG antibodies is an indicator of a past infection. The time of infection can roughly be estimated in IgM positive patients by a CMV IgG avidity test3.

A low-avidity anti-CMV IgG detected before the 16th – 18th week of pregnancy, together with a positive anti-CMV IgM, is strong evidence of a recent primary infection, whereas a high avidity index during the first 12 – 16 weeks would be considered a good indicator of past infection.2 A high avidity result later in gestation cannot rule out a primary infection at an earlier stage of the pregnancy.2

Elecsys® CMV IgG

Elecsys® CMV IgG5

  • Systems

    cobas e 411 analyzer, cobas e 601 / cobas e 602 modules, cobas e 402 / cobas e 801 analytical units

  • Testing Time

    18 minutes


  • Test principle

    One-step double antigen sandwich immunoassay


  • Calibration



  • Interpretation

    <0.5 U/mL = non-reactive
    0.5 – 1.0 U/mL = indeterminate
    ≥1.0 U/mL = reactive


  • Traceability

    This method has been standardized against a Roche standard (arbitrary units)


  • Sample material

    Serum collected using standard sampling tubes or tubes containing separating   gel. Li‑heparin, Na‑heparin, K2‑EDTA, K3‑EDTA, ACD, CPD, CP2D, CPDA and Na‑citrate plasma.
    Specimen collected from living patients, blood donors, or individual organ, tissue or cell donors may be used, including donor samples obtained while the donor’s heart is still beating.

  • Sample volume

    20 μL cobas e 411 analyzer, cobas e 601 / cobas e 602 modules
    12 μL cobas e 402 / cobas e 801 analytical units

  • Onboard stability

    3 weeks for cobas e 411 analyzer, cobas e 601 / cobas e 602 modules
    16 weeks for cobas e 402 / cobas e 801 analytical units

  • Intermediate precision

    cobas e 411 analyzer: CV 2.8 – 3.9 %       
    cobas e 601 / 602 modules: CV 1.1 – 4.6 %  
    cobas e 402 / cobas e 801 analytical units: CV 1.8 – 2.4 %

  • Agreement with a commercially available method

    98.9 % (n = 532)
    96.8 % (n = 616)
    99.4 % (n = 520)    

The measured CMV IgG value of a patient’s sample can vary depending on the testing procedure used. The laboratory finding must therefore always contain  a statement on the CMV IgG assay method used. CMV IgG values  determined on patient samples by different testing procedures cannot be directly compared with one another and could be the cause of erroneous medical interpretation.


  1. Van Zuylen WJ, et al. Congenital cytomegalovirus infection: Clinical presentation, epidemiology, diagnosis and prevention. Obstet Med. 2014; 7(4):140–146.
  2. Buxmann H, et al. Primary Human Cytomegalovirus (HCMV) Infection in Pregnancy. Dtsch Arztebl Int. 2017; 114(4):45–52.
  3. Revello MG, Gerna G. Diagnosis and Management of Human Cytomegalovirus Infection in the Mother, Fetus, and Newborn Infant. Clin Microbiol Rev. 2002; 15(4):680–715.
  4. Shahar-Nissan K, et al. Valaciclovir to prevent vertical transmission of cytomegalovirus after maternal primary infection during pregnancy: a randomised, double-blind, placebo-controlled trial. Lancet 2020; 396: 779–85.
  5. Elecsys® CMV IgG (#09118543190, #09118551190) method sheet 2022, V. 1.0.