Repeated Detection of Rubella Virus IgM Antibodies in Two Pregnancies Without Evidence of Fetal Infection: A Case Report and Challenges in Serological Interpretation

TL;DR

A pregnant woman repeatedly tested positive for rubella IgM antibodies, but her babies were healthy, showing possible false positives or non-specific immune reactions.

Contribution

The study highlights challenges in interpreting rubella IgM antibody tests during pregnancy and emphasizes the need for clinical context and supplemental testing.

Findings

A woman tested positive for rubella IgM antibodies in two pregnancies but delivered healthy babies.

No fetal infection was detected through sonography or serology.

False positives or persistent IgM antibodies may explain the results.

Abstract

Serologic screening for rubella virus, as part of TORCH testing during pregnancy, remains a cornerstone in the prevention of congenital rubella syndrome. However, isolated detection of rubella-specific IgM antibodies may lead to diagnostic uncertainty, especially in the absence of clinical signs or supporting serological evidence. We present a case of a pregnant woman who tested positive for rubella IgM antibodies during two consecutive pregnancies, despite lacking any sonographic or serologic indications of fetal infection. Both pregnancies culminated in the delivery of healthy neonates with no clinical or laboratory evidence of congenital rubella. This case highlights the possibility of false-positive IgM results, persistent IgM antibodies, or nonspecific immune reactivity. Timely clarification of such findings is essential to avoid unnecessary anxiety and invasive procedures. Interpretation of rubella IgM results should always consider the clinical context, supplemental serologic tests (such as IgG avidity), and current epidemiological data.