What additional investigations are required for a newly diagnosed pregnant female with Hepatitis B surface antigen (HBsAg) positive?

Evaluation and Management of HBsAg-Positive Pregnant Women

All HBsAg-positive pregnant women should be tested for HBV DNA to guide the use of maternal antiviral therapy during pregnancy for the prevention of perinatal HBV transmission. 1

Initial Evaluation

• All pregnant women should be tested for HBsAg during an early prenatal visit (first trimester) in each pregnancy, even if previously vaccinated or tested 1
• For newly diagnosed HBsAg-positive pregnant women, the following investigations are required:
  • HBV DNA quantification to assess viral load and risk of mother-to-child transmission 1
  • Hepatitis B e antigen (HBeAg) status to help assess infectivity 1, 2
  • Alanine aminotransferase (ALT) levels to assess liver inflammation 1, 3
  • Assessment for advanced fibrosis or cirrhosis 1

Management Based on Test Results

For HBV DNA Management:

• If HBV DNA >200,000 IU/mL:
  • Initiate antiviral prophylaxis with tenofovir disoproxil fumarate (TDF) at weeks 24-28 of gestation 1
  • Continue antiviral therapy until 12 weeks after delivery 1
• If HBV DNA <200,000 IU/mL:
  • Antiviral therapy is not required solely for prevention of perinatal transmission 1
  • Continue monitoring HBV DNA levels throughout pregnancy 1

For Women with Advanced Fibrosis or Cirrhosis:

• Therapy with tenofovir is recommended regardless of viral load 1
• Those already on antiviral treatment with tenofovir should continue the treatment throughout pregnancy 1

Monitoring During and After Pregnancy

• Monitor ALT and HBV DNA for 6 months postpartum or after cessation of antivirals 1
• HBsAg-positive pregnant women should be referred to their jurisdiction's Perinatal Hepatitis B Prevention Program (PHBPP) for case management 1
• A copy of the laboratory report indicating HBsAg-positive status should be provided to the hospital where delivery is planned and to the healthcare provider who will care for the newborn 1

Infant Care Planning

• Ensure the infant receives hepatitis B vaccine and HBIG (Hepatitis B Immunoglobulin) within 12 hours of birth 1
• Plan for completion of the infant's vaccine series and post-vaccination serologic testing 1

Special Considerations

• HBeAg-positive pregnant women or those with high HBV DNA levels should be counseled about the high risk of HBV transmission associated with invasive procedures like amniocentesis 1
• Non-invasive prenatal testing is preferred over amniocentesis when possible 1
• Breastfeeding is not contraindicated for HBsAg-positive mothers, even when on antiviral therapy with tenofovir 1

Common Pitfalls to Avoid

• Failure to test for HBV DNA: Studies show that up to 55.7% of HBsAg-positive pregnant women do not receive HBV DNA testing during pregnancy 3
• Inadequate monitoring: Only 47% of HBsAg-positive pregnant women receive ALT testing in the 12 months after delivery 3
• Delayed referral to hepatology: About two-thirds of HBsAg-positive pregnant women do not receive specialized care for HBV infection during pregnancy 4
• Relying solely on HBeAg status: Using both HBeAg and ALT levels provides better prediction of high viral load than HBeAg alone 2