Isolated congenital heart block is linked to transplacental passage of maternal anti-SSA/Ro and/or anti-SSB/La antibodies that may be related to a connective tissue disease. Ultrasonography and Doppler are essential to screen fetus at risk. They allow the diagnosis of first- and second-degree blocks which are probably preliminary stages in conducting tissue's injury. In these situations, a maternal treatment by fluorinated steroids can be proposed because of its possible effect on partial blocks. However, these early signs of nodal injury can be lacking: some fetus present a complete heart block without previously detected less advanced block. Moreover, the significance of first-degree block is unclear since it could reverse spontaneously. Other markers of nodal injury would be valuable. In case of complete congenital heart block, ultrasonography is useful to detect congestive heart failure and help the obstetrical management when unfavorable prognostic signs occur.