Management and Treatment of Parvovirus B19 Infection During Pregnancy
Pregnant women with suspected or confirmed parvovirus B19 infection should be referred to a maternal-fetal medicine specialist for close monitoring with serial ultrasounds every 1-2 weeks for up to 12 weeks after infection, with particular attention to Doppler measurement of the middle cerebral artery peak systolic velocity to detect fetal anemia. 1
Diagnosis and Initial Assessment
Maternal diagnosis:
- Test for parvovirus B19 IgG and IgM antibodies in pregnant women with:
- Known exposure to parvovirus B19
- Symptoms of infection (rash, arthralgia, fever)
- Unexplained fetal hydrops or intrauterine fetal death 1
- Test for parvovirus B19 IgG and IgM antibodies in pregnant women with:
Interpretation of serology results:
- IgG positive, IgM negative: Woman is immune, no risk to pregnancy
- IgG negative, IgM negative: Woman is susceptible but not infected
- IgG positive or negative, IgM positive: Recent infection, requires fetal monitoring 1
Fetal diagnosis:
- PCR testing of amniotic fluid via amniocentesis if maternal infection is confirmed and fetal involvement is suspected 2
- Not routinely recommended unless abnormal ultrasound findings are present
Monitoring Protocol
Ultrasound surveillance:
- Begin monitoring 2-4 weeks after maternal infection
- Continue serial ultrasounds every 1-2 weeks for up to 12 weeks after infection 1
- Look for signs of fetal hydrops (ascites, pleural/pericardial effusion, skin edema, placental thickening)
Doppler assessment:
- Measure middle cerebral artery peak systolic velocity (MCA-PSV) to detect fetal anemia
- MCA-PSV >1.5 MoM suggests significant fetal anemia requiring intervention 3
Management Based on Fetal Status
For Fetuses Without Evidence of Anemia or Hydrops:
- Continue regular ultrasound monitoring
- No specific intervention required
- Normal pregnancy management
For Fetuses With Evidence of Anemia (Elevated MCA-PSV) or Hydrops:
Immediate referral to a center capable of fetal blood sampling and intrauterine transfusion 1
Cordocentesis to:
- Confirm fetal anemia
- Perform PCR for parvovirus B19
- Determine fetal blood type and hematocrit
Intrauterine transfusion (IUT):
- Indicated for moderate to severe fetal anemia
- Perinatal survival rates following IUT range from 67% to 85% 4
- May need to be repeated if anemia recurs
Monitoring after transfusion:
- Weekly ultrasound assessment for 8-10 weeks
- Repeat MCA-PSV measurements
- Additional transfusions as needed based on MCA-PSV values
Special Considerations
Timing of infection:
Mild fetal anemia:
- If anemia is mild and no hydrops is present, non-invasive monitoring may be sufficient
- Some cases of mild hydrops may resolve spontaneously 4
Alternative therapies:
- Intravenous immunoglobulin (IVIG) has been described as an alternative therapy for fetal hydrops in some cases 4
- Not standard of care but may be considered in specific situations
Prevention
- No vaccine is currently available for parvovirus B19 2
- Pregnant women should:
- Practice good hand hygiene
- Avoid close contact with individuals with suspected infection
- Consider temporary absence from high-risk environments (e.g., schools with outbreaks) on a case-by-case basis 1
Prognosis and Follow-up
- Maternal-fetal transmission occurs in approximately 30-50% of maternal infections 3
- Most infected fetuses have normal outcomes without intervention
- Long-term follow-up is recommended for infants with history of fetal hydrops or intrauterine transfusion
- Evaluate infants for potential long-term sequelae, which may occur even after successful treatment 3
Common Pitfalls to Avoid
- Failing to test for parvovirus B19 in cases of unexplained fetal hydrops
- Inadequate duration of monitoring (should continue for up to 12 weeks after infection)
- Delaying referral to specialists when fetal anemia is suspected
- Performing invasive procedures unnecessarily when mild anemia can be monitored non-invasively