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Difficulty: Very hardClinical Preventive Services and Screening

A 28-year-old primigravida presents for her first prenatal visit at 10 weeks of gestation. She recently immigrated from an area with high endemicity for hepatitis B. Arrange the following clinical preventive, diagnostic, and surveillance steps in the correct chronological order to appropriately screen, evaluate, and manage this patient and her future offspring to minimize vertical transmission.

  1. 1Perform initial universal maternal screening with a hepatitis B surface antigen (HBsAg) test.
  2. 2Quantify maternal hepatitis B virus (HBV) DNA levels and determine HBeAg status.
  3. 3Initiate maternal antiviral prophylaxis with tenofovir disoproxil fumarate at 28 to 32 weeks of gestation.
  4. 4Administer the hepatitis B vaccine and hepatitis B immune globulin (HBIG) to the neonate within 12 hours of birth.
  5. 5Conduct infant post-vaccination serologic testing with HBsAg and anti-HBs at 9 to 12 months of age.

Answer

The correct chronological sequence is: 1) Maternal HBsAg screening at the first prenatal visit, 2) Quantification of maternal HBV DNA and HBeAg, 3) Initiation of maternal tenofovir prophylaxis in the third trimester if indicated, 4) Administration of the HBV vaccine and HBIG to the newborn within 12 hours of birth, and 5) Infant post-vaccination serologic testing at 9 to 12 months of age.
The correct sequence mirrors the standard clinical pathway for preventing vertical transmission of Hepatitis B. It begins with population-level screening (HBsAg), followed by risk stratification via viral load quantification (HBV DNA). High-risk mothers receive targeted third-trimester antiviral therapy (tenofovir) to lower viremia. At delivery, the neonate receives immediate post-exposure prophylaxis (vaccine and HBIG). Finally, the success of these interventions is confirmed via serologic surveillance at 9 to 12 months, allowing sufficient time for the infant's endogenous immune response to develop and for exogenous HBIG to wane.

Step-by-Step Solution

1
Perform universal maternal HBsAg screening.
Identifies maternal HBV infection status early in pregnancy.
Required by USPSTF to identify pregnancies at high risk for perinatal HBV transmission, setting the cascade in motion.
2
Measure maternal HBV DNA and HBeAg.
Determines the level of maternal viremia and relative infectivity.
A high viral load (>200,000 IU/mL) indicates a significant risk of immunoprophylaxis failure at birth, necessitating additional prenatal interventions.
3
Administer maternal antiviral therapy at 28-32 weeks.
Reduces maternal viral load prior to the onset of labor.
Minimizes the risk of fetal exposure to high levels of the virus during the birthing process when maternal-fetal blood mixing occurs.
4
Give HBIG and HBV vaccine to the neonate within 12 hours of birth.
Provides immediate passive and active immunity to the neonate.
Highly effective at preventing chronic HBV infection when administered immediately following delivery.
5
Check infant HBsAg and anti-HBs at 9-12 months.
Confirms the infant is protected (anti-HBs positive) and not infected (HBsAg negative).
Testing before 9 months may yield false-positive anti-HBs results due to the passively transferred HBIG administered at birth.

Key Concept

Prevention of Perinatal Hepatitis B Transmission
Estimated Time:1m 30s
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Topics

Clinical Preventive Services and Screening

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