A mother tests HBsAg +ve on antenatal screening.
1) What other blood tests are indicated here in light of this result?
Anti-HB core Abs
HBV viral load (guidelines differ, but pregnant women with high viral loads may be candidates for anti-viral agents in the third trimester to reduce the chances of mother to child transmission (MTCT))
Liver function tests (LFTs)
(Unless the mother is acutely unwell there is little point in performing anti-HBcore IgM Abs. A positive screening test is almost always going to indicate chronic Hepatitis B infection)
2) What should all neonates born to HBsAg +ve mothers receive?
Regardless of whether the mother received anti-virals, all neonates born to HBsAg +ve mothers should receive Hep B immunisation (1st dose at birth) and Hepatitis B immunoglobulin. Both passive and active immunisation together reduces the risk of MTCT by 90%.
3) What laboratory tests should be performed on the baby?
Guidelines differ with regards to this but my preference is for HBsAg and anti-HBsAb at 9-12 months. At this age confusing maternal antibodies should be gone and a clear interpretation can be made on the lab results.