Journal of Ultrasound in Medicine, Vol 12, Issue 2 97-101, Copyright © 1993 by American Institute of Ultrasound in Medicine
Fetal syphilis: correlation of sonographic findings and rabbit infectivity testing of amniotic fluid
L. Nathan, D. M. Twickler, M. T. Peters, P. J. Sanchez and G. D. Wendel Jr
Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, Dallas 75235-9032.
Fetal syphilis is the presumed diagnosis when the sonographic findings of
fetal hydrops are found in the presence of maternal syphilis. In the
absence of fetal hydrops, the diagnosis of fetal infection is difficult. We
hypothesized that intra-amniotic infection would be accompanied by anatomic
placental and fetal abnormalities that could be detected by
ultrasonography. Rabbit infectivity testing (RIT), intratesticular
inoculation of rabbits with amniotic fluid, can be used to confirm
intra-amniotic infection with Treponema pallidum. Twenty-one gravidas with
untreated early (primary, secondary, and early latent) syphilis underwent
sonography and amniocentesis for RIT at 24 weeks of gestation or later.
Antenatal sonographic findings were compared to their amniotic fluid RIT
results. Hepatomegaly was significantly (P < 0.01) associated with
amniotic fluid infection detected by RIT. Antenatal detection of
hepatomegaly, which is probably the initial sonographic manifestation of
hydrops fetalis, may ultimately identify the fetus affected with congenital
syphilis.
