The test is done to diagnose syphilis in a newborn if the mother is syphilitic is
High-Yield Explanation
Diagnosis of congenital syphilisIt involves Dark ground Microscopy and VDRL.As IgM does not cross the placenta, its presence in neonatal serum confirms congenital syphilis and helps to differentiate it from seropositivity due to passively transferred maternal antibodies. The tests to detect IgM are-FTA-ABS (19S IgM FTA-ABS)Syphilis Capita M test(Refer: Nelson's Textbook of Pediatrics, SAE, 1st edition, pg no. 1475-1477)