<prompt> Congenital syphilis can be best diagnosed by ?IgM FTA- ABSIgG FTA-ABSVDRLTPI  <response>: Ans. is a i.e., IgM FTA-ABS Lab diagnosis of congenital syphils . As Ig M does not cross placenta, its presence in neonatal serum confirms congenital syphilis and helps differentiating it from seropositivity due to passively tranfered maternal antibodies. The tests to detect IgM are: . FTA-ABS 19S IgM FTA-ABS . Syphilis Capita M test For measurment of Ig M in neonate in whom congenital syphilis is suspected, the syphilis capita M test and the 19S IgM FTA-ABS test are available. - Note - lre Harrison says, No commercially available IgM test is recommeded for evaluation of infant with suspected congenital syphillis. - 1043 