What is the next step for a pregnant woman at 29 weeks gestation with a negative Immunoglobulin G (IgG) result for rubella after exposure to a student with rubella?

Management of Rubella Exposure in a Seronegative Pregnant Woman at 29 Weeks

For a pregnant woman at 29 weeks gestation with negative rubella IgG who has been exposed to rubella, the next step should be close monitoring for symptoms while understanding that immune globulin is not recommended as it will not prevent infection or viremia.

Understanding the Situation

• A negative rubella IgG test indicates susceptibility to rubella infection 1
• At 29 weeks gestation, the risk of congenital rubella syndrome (CRS) is significantly lower than in the first trimester, though maternal infection remains concerning 1
• Exposure to a student with rubella requires prompt evaluation and management 1

Recommended Management Approach

Immediate Steps

• Obtain a detailed exposure history and assess for any symptoms of rubella infection 1
• Immune globulin (IG) is NOT recommended for post-exposure prophylaxis as it:
  • Will not prevent infection or viremia 1
  • May only modify or suppress symptoms, creating a false sense of security 1
  • Has not been proven effective (infants with congenital rubella have been born to women given IG shortly after exposure) 1

Monitoring and Testing

• Monitor closely for development of rubella symptoms (rash, fever, lymphadenopathy) 1
• If symptoms develop, obtain serum for rubella-specific IgM antibody testing 1
  • IgM testing is most reliable when collected between 1-2 weeks after rash onset 1
• Consider paired sera testing if symptoms develop:
  • Acute-phase serum as soon as possible after symptom onset 1
  • Convalescent-phase serum 10 or more days after the acute-phase specimen 1

Special Considerations

• The only instance where IG might be considered (though still not highly recommended) is when a pregnant woman who has been exposed to rubella would not consider termination of pregnancy under any circumstances 1
• At 29 weeks gestation, the risk of severe congenital defects is much lower than during the first trimester 1

Post-Pregnancy Management

• Vaccination against rubella should be administered postpartum if the woman remains seronegative 1
• Counsel the patient to avoid pregnancy for 3 months following vaccination 1

Important Caveats

• Serologic confirmation of rubella infection in pregnant women can be difficult and often yields nonconfirmatory results 1
• False-negative IgM results can occur even when specimens are appropriately drawn 1
• The effectiveness of immune globulin for preventing rubella is questionable, with studies showing varying results 2
• Some individuals may have protective immunity against rubella despite negative RV-IgG results, through cell-mediated immunity 3