What is your approach to screening for complete heart block in an asymptomatic pregnant patient with negative SSA and positive SSB antibodies?

There are case reports of congenital heart block (CHB) due to anti-RNP antibody in anti-SSA/SSB-negative pregnant women (Izmirly et al., PMID 28709760). However, it is so rare that too many fetal heart monitoring tests would need to be done to identify these rare events. The amount of time and money spent doing the tests certainly would not be worth it. 

However, it is important to realize that CHB can occur in an anti-RNP-positive woman who is negative for anti-SSA/SSB antibodies, and the appropriate steps be taken if identified. In the case of a fetal loss in this scenario, asking the parents if they would consider allowing an autopsy and the involvement of a neonatal lupus expert (such as NYU Langone's Lupus Center) would be important so that we can learn more about the pathophysiology and why this would occur with anti-RNP in some women.