Serum testing, testing that is performed on blood, usually consists of looking for the antibodies to chlamydia and gonorrhea. The IgG antibody test checks for antibodies that are usually present more than 3 months after infection. The presence of of IgG usually sugggests an active or resolved infection. The IgM antibody test looks for antibodies that are usually present less than one month after exposure. Positive IgM suggests recent infection.