Understanding Lab Tests for Congenital Varicella Syndrome
Written by Private MD Labs Medical Writing Team • Last Updated: September 8, 2025
Congenital Varicella Syndrome is a rare birth defect condition that can occur when a pregnant woman contracts chickenpox (varicella-zoster virus) during the first 20 weeks of pregnancy. While the syndrome itself is diagnosed through clinical examination and imaging of the affected infant, blood testing plays a crucial role in assessing maternal immunity and understanding risk factors.
Recommended Test
Varicella-Zoster Virus (VZV) Antibodies, IgG (Chickenpox)
This test measures IgG antibodies against the varicella-zoster virus in the blood, indicating past exposure or vaccination. For pregnant women or those planning pregnancy, this test helps determine immunity status. If antibodies are present, the mother is protected and unlikely to contract chickenpox during pregnancy, thus protecting the fetus from potential congenital varicella syndrome.
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The Role of Blood Testing in Congenital Varicella Syndrome
There is no single blood test to diagnose Congenital Varicella Syndrome after birth, as this is primarily determined by physical examination and imaging studies. However, laboratory testing is fundamental for assessing maternal immunity to varicella-zoster virus, which helps determine the risk of transmission to the developing fetus during pregnancy.
Understanding the Results
A positive VZV IgG antibody test indicates immunity to chickenpox, either from previous infection or vaccination. This immunity significantly reduces the risk of maternal chickenpox infection during pregnancy and subsequent risk to the developing fetus. A negative result suggests lack of immunity and may warrant vaccination before pregnancy or special precautions during pregnancy.
Important Considerations
The information here is for educational purposes only and is not a substitute for professional medical advice. Always consult with a healthcare provider for diagnosis, treatment, and prenatal care guidance.
