Hepatitis B in pregnancy with a high viral load — structured SAQ (15 marks)

(a) Transmission risk and why it matters (3 marks)

One mark for the rate, one for the chronicity, one for the rationale. ^[1]

• Transmission risk: without immunoprophylaxis, the perinatal transmission rate in HBeAg-positive mothers is 70 to 90%. This woman is HBeAg-positive with a high viral load (8 million IU per mL), placing her in the highest-risk group.^[1]
• Chronicity: about 90% of infants infected perinatally develop chronic hepatitis B infection, with the later risk of cirrhosis and hepatocellular carcinoma.^[2]
• Rationale: preventing the perinatal infection prevents the chronic disease and its long-term sequelae — this is why the prevention plan is time-critical and non-negotiable.^[1][2]

(b) Antenatal management from 28 weeks and antiviral prophylaxis (4 marks)

One mark each for the agent, the timing, the threshold rationale, and the plan for delivery. ^[3][4]

• Agent: tenofovir disoproxil fumarate, the preferred antiviral in pregnancy for hepatitis B prophylaxis.^[3]
• Timing: commenced in the third trimester (typically from 28 to 32 weeks) and continued to delivery and the early postpartum period.^[3][4]
• Threshold rationale: her viral load of 8 million IU per mL is well above the threshold of approximately 200,000 IU per mL at which antiviral prophylaxis is recommended, to reduce perinatal transmission. The aim is to suppress the viral load by delivery.^[3]
• Delivery plan: plan for a birth where the birth-dose immunoprophylaxis can be given within 12 to 24 hours; liaise with the paediatric team before delivery. The combined antiviral plus immunoprophylaxis approach reduces transmission to under 1%.^[1]

(c) Neonatal immunoprophylaxis regimen (4 marks)

One mark each for the active agent, the passive agent, the timing, and the subsequent course. ^[1]

• Active immunisation: the hepatitis B vaccine, given as the birth dose.^[1]
• Passive immunisation: hepatitis B immunoglobulin (HBIG), given alongside the vaccine.^[1]
• Timing: both the vaccine and the immunoglobulin must be given within 12 to 24 hours of birth. This is the time-critical step that prevents approximately 94% of perinatal infections.^[1]
• Subsequent course: the hepatitis B vaccine course is completed with further doses over the following months (typically a three- or four-dose schedule), and the infant's HBsAg status is checked at 9 to 12 months to confirm protection or infection.^[1][2]

(d) Breastfeeding, follow-up and family counselling (4 marks)

One mark for breastfeeding, one for infant follow-up, two for partner and family testing and prevention. ^[2][3]

• Breastfeeding: breastfeeding is not contraindicated in hepatitis B provided the infant has received the timely birth-dose immunoprophylaxis (vaccine and immunoglobulin within 12 to 24 hours).^[1][3]
• Infant follow-up: complete the vaccine course and check the infant's HBsAg status at 9 to 12 months to confirm protection versus chronic infection.^[2]
• Partner and family testing: the partner and other children should be tested for hepatitis B, and those who are non-immune should be vaccinated. This is the household prevention step.^[1][3]
• Maternal follow-up: monitor the maternal liver function and viral load in the postpartum period, and arrange specialist hepatology follow-up for her own chronic infection management.^[3]