TABLE 2. Specimen types, storage, and transport for direct detection tests for Treponema pallidum — CDC laboratory recommendations for syphilis testing, United States, 2024.

Direct detection test	Specimen types	Specimen storage and transport
Darkfield microscopy	Serous exudate of moist lesions (except oral lesions) should be collected directly on a microscope slide or using a sterile bacteriological loop; avoid red blood cells	Fresh, room temperature (20°C to 26°C; 68°F to78.8°F)
Immunofluorescent antibody test staining	Smear from suspected lesion(s)	Fresh, room temperature (20°C to 26°C; 68°F to 78.8°F)
Immunohistochemistry staining	Formalin-fixed and paraffin-embedded tissue sections of brain, placenta, umbilical cord, or skin lesions from secondary or tertiary syphilis	Room temperature (20°C to 26°C; 68°F to 78.8°F)
Silver stain	Formalin fixed and paraffin embedded tissue sections of brain, placenta, umbilical cord, or skin lesions from secondary, tertiary, or congenital syphilis	Room temperature (20°C to 26°C; 68°F to 78.8°F)
Nucleic acid amplification test	Primary syphilis:    Serous exudate of moist lesions should be collected with a sterile Dacron swab and placed in a commercial transport medium Secondary syphilis:    Mucous patches and condyloma lata specimens should be collected with a sterile Dacron swab and placed in a commercial transport medium    Fresh frozen tissue biopsy or formalin-fixed and paraffin-embedded tissue    Neonatal whole blood or serum; whole blood should be collected in an EDTA (purple top) tube	Frozen (−20°C to −80°C; −4°F to −112°F), frozen ice packs or dry ice