TORCH Panel
TORCH is an acronym for a group of infections that can cross the placenta and cause congenital defects: Toxoplasma, Other (syphilis, varicella, parvovirus B19), Rubella, Cytomegalovirus (CMV), and Herpes simplex virus (HSV). The TORCH panel measures IgM and IgG antibodies to each pathogen. Routine universal TORCH screening is controversial and increasingly discouraged — it has high false positive rates and often causes unnecessary anxiety. Targeted testing when there is a reason to suspect infection is preferred.
Expected Result
Normal
IgM negative, IgG reflects past exposure
Avidity testing on positive IgG helps determine whether an infection is recent or remote — key in pregnancy counseling.
This is a qualitative test — results are reported as positive or negative rather than as a numeric range. Interpretation may vary by laboratory method; always review with your doctor.
What a Negative Result Means
Negative IgM and negative IgG mean no past infection and no immunity — relevant for counseling about exposure risk during pregnancy (avoid raw meat and cat litter for toxoplasma, avoid rubella and varicella contacts if non-immune). Rubella-susceptible women should receive MMR vaccine before pregnancy, not during.
What a Positive Result Means
Positive IgG with negative IgM usually means past infection and immunity — in pregnancy this is reassuring for rubella, toxoplasma, and CMV. Positive IgM suggests recent infection or reactivation; IgG avidity testing distinguishes recent (low avidity) from remote (high avidity) infection and guides the need for further testing such as amniocentesis PCR. False positives on IgM are common, so any positive IgM should be confirmed and interpreted by someone experienced in fetal medicine.
Frequently Asked Questions
Should every pregnant woman get a TORCH panel?
No — universal TORCH screening is not recommended by major guidelines. IgM false positives are common and cause unnecessary anxiety, amniocentesis, and even termination of pregnancy. Targeted testing is appropriate: rubella immunity at booking, and specific testing when ultrasound findings (growth restriction, calcifications, microcephaly) or exposure history prompts concern.
What is IgG avidity and why does it matter?
IgG avidity measures how tightly antibodies bind their target — low avidity means recent infection (within 3–4 months), high avidity means older infection (safe in pregnancy). Avidity testing on positive IgG is critical when IgM is also positive and the timing of infection changes management. Many Indian labs now offer avidity testing for toxoplasma and CMV.
How is CMV handled in pregnancy?
Routine screening is not recommended in India. Primary CMV infection in pregnancy is the highest-risk scenario. If suspected (flu-like illness, abnormal ultrasound, occupational exposure to toddlers), IgM plus avidity and sometimes PCR on amniotic fluid guide risk assessment. Anti-CMV hyperimmune globulin and valaciclovir are investigational options in specialist centers; basic hand hygiene and avoiding toddler saliva/urine are the mainstays of prevention.
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InfectiousDengue IgM Antibody
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This information is for educational purposes only and should not replace professional medical advice. Always consult your doctor for interpretation of your test results.
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