SBA — Single Best Answer · Review
Question 28
Feto-maternal medicine → Perinatology
Classification
Question
SSBAQuestion Header
Hepatitis B and invasive testing
Question Stem
A pregnant woman with hepatitis B is considering invasive prenatal diagnosis. Which factor is most important when counselling her about the risk of mother-to-child transmission associated with the procedure?
Options
A
Maternal age
B
Fetal sex
C
Placental location alone
D
Maternal hepatitis B viral load
E
Parity
Explanation
For women with hepatitis B undergoing invasive prenatal diagnosis, counselling should take account of maternal viral load. RCOG reports that mother-to-child transmission risk is low when the viral load is below approximately 6.99 log10 copies/mL and rises at higher viral loads. The decision to undertake invasive testing should therefore be individualised after reviewing maternal infection status and virological results.
Option Validity
A) Maternal age does not determine hepatitis B vertical transmission risk during invasive testing.
B) Fetal sex is not the principal determinant of hepatitis B transmission risk.
C) Placental location may affect procedural technique but does not replace assessment of maternal viral load for transmission counselling.
E) Parity is not the principal determinant of hepatitis B mother-to-child transmission risk.
Further Reading
Navaratnam K, Alfirevic Z; Royal College of Obstetricians and Gynaecologists. Amniocentesis and chorionic villus sampling: Green-top Guideline No. 8. BJOG. 2022;129:e1-e15.