Master the board step 3

Obstetrics
Syphilis
If the case describes a previously treated syphilis infection, never assume
immunity. There is no immunity from prior infection with syphilis, and reinfection
can occur over and over again.
Transplacental infection results from primary and secondary infection (60
percent risk of transmission). The lowest risk of transmission is with latent or
tertiary infection.
Early acquired (first trimester) congenital syphilis includes the following
symptoms/outcomes:
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Nonimmune hydrops fetalis
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Maculopapular or vesicular peripheral rash
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Anemia, thrombocytopenia, and hepatosplenomegaly
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Large and edematous placenta
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Perinatal mortality rates ~ 50 percent
Late-acquired congenital syphilis is diagnosed after 2 years of age and
includes the following symptoms:
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Hutchinson teeth • “Saber” shins
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“Mulberry” molars • Deafness (cranial nerve 8 palsy)
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“Saddle” nose
Diagnostic Testing
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VDRL or RPR screening in first trimester. Confirm (+) screen with FTA-ABS.
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Screening test will be falsely negative in primary syphilis.
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When the case describes a woman with a painless genital ulcer, order
darkfield microscopy for diagnosis of primary syphilis.
Always order an HIV test
in any pregnant patient
who has tested positive for
an STD.
C-section will not prevent
vertical transmission of
syphilis, because it happens
through the placenta
before birth.
Treatment
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Benzathine penicillin IM × 1 for (+) mothers
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Penicillin allergy: Oral desensitization followed by full dose benzathine
penicillin
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