The Jarisch-Herxheimer Reaction and Fetal Monitoring Changes in Pregnant Women Treated for Syphilis
Abstract & Commentary
Synopsis: The Jarisch-Herxheimer reaction occurs in approximately 40% of pregnant patients treated for syphilis.
Source: Myles TD, et al. Obstet Gynecol 1998;92: 859-864.
The jarisch-herxheimer reaction is a poorly understood condition that occurs in approximately one-half of all individuals treated for syphilis. Some reports have found the condition to occur only with primary and secondary syphilis, whereas others have noted its occurrence also with the latent stages of syphilis.
Pregnant patients who receive penicillin therapy for syphilis are reported to have uterine contractions and, on occasion, fetal death. Because of the scattered reports, fetal heart rate (FHR) monitoring is commonly recommended, even though most of the reports in the literature were written before FHR monitoring was developed.
Myles and colleagues reviewed their hospital’s experience with the treatment of syphilis in women greater than 24 weeks gestation. Their protocol required FHR monitoring for a minimum of 10 minutes prior to penicillin therapy and for 24 hours afterward. Fifty patients fulfilled the study criteria, and fetal monitoring strips were available for 31. The hospital charts and FHR recordings were reviewed by Myles et al.
Forty percent of the patients experienced signs or symptoms of the Jarisch-Herxheimer reaction—primarily an increase in temperature. Forty-two percent of those patients with FHR records had uterine contractions following penicillin therapy. Interestingly, the median time from treatment to the onset of contractions was 10 hours, with a range of 2-18 hours. In all cases, the contractions resolved within 24 hours. Of those with contractions, approximately 50% developed variable decelerations for at least some period of time. Regular late decelerations were not observed. Except for one fetus born with congenital syphilis, there were ultimately no fetal abnormalities (though there were 5 premature births). Three of these occurred in women with a Jarisch-Herxheimer reaction. Overall, nearly two-thirds of the patients had the Jarisch-Herxheimer reaction, and/or uterine contractions, and/or variable decelerations.
Comment by Kenneth Noller, MD
For several years, it has fallen to me to give the lecture to our third-year students concerning sexually transmissible diseases in pregnancy. Because I love eponyms (and, of course, the students hate them) I always mention that the treatment of syphilis in pregnancy can be associated with fetal stress due to the Jarisch-Herxheimer reaction. I stress the need for fetal monitoring when penicillin is given to a patient for the treatment of syphilis and when the fetus is of viable gestational age.
This report suggests that I might be "overselling" the effect on the fetus. This is a relatively large series, yet no significant fetal compromise was caused by the Jarisch-Herxheimer reaction. Whether fetal stress (or even demise) can be associated with the reaction cannot be determined with certainty, as it may be so infrequent that this relatively large series is still far too small to detect an increase in fetal wastage. For the present time, it is probably still a good idea to monitor patients for a relatively long period of time after they receive their initial penicillin therapy for the treatment of syphilis.
Unfortunately, Myles et al did not choose to examine the occurrence of the Jarisch-Herxheimer reaction in patients before 24 weeks gestation, when most syphilis is detected and treated. Although fetal monitoring at that early gestational age would not be useful, it would be interesting to know if there is a difference in the frequency of the reaction.
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