Recognizing and Treating Syphilis in Pregnancy

, , University of South Florida College of Medicine; , , Veteran Administration Hospital.

Disclosures

Medscape General Medicine. 1998;1(3) 

In This Article

Abstract and Introduction

Abstract

The number of primary and secondary syphilis cases in young women rose dramatically in the late 1980s and early 1990s, due to illicit drug use and the exchange of drugs for sex. Of infants born to mothers with primary or secondary syphilis, up to 50% will be premature, stillborn, or die in the neonatal period; further, most of these children are born with congenital disease that may not be apparent for years. While appropriate treatment of the pregnant female can prevent congenital syphilis, the major deterrent has been the inability to effectively identify these women and get them to undergo treatment. In determining a penicillin regimen, the clinician must consider the stage of maternal infection, the length of fetal exposure, and physiologic changes in pregnancy that can affect the pharmacokinetics of antibiotics. Treatment decisions may be further complicated in patients who are allergic to penicillin or infected with HIV. The pathogenesis of congenital syphilis is not completely understood, but placental invasion is the presumed major route. All women should be screened for syphilis with a nontreponemal test (eg, rapid plasma reagin [RPR] or venereal disease research laboratory [VDRL] test) in the first trimester. Those at high risk should be retested at 28 weeks and near delivery. Even with appropriate treatment of syphilis during pregnancy, fetal infection may still occur in up to 14% of cases. Treating syphilis during pregnancy can be difficult due to physiologic changes that can alter drug levels and the risk that drugs will induce uterine contractions or compromise the health of the fetus. While there are added risks and potential complications, treatment regimens parallel those in nonpregnant women.

Introduction

Despite the availability of successful therapy for syphilis since the development of long-acting penicillin in the early 1950s, prevention of congenital syphilis remains a challenge. There has been a dramatic increase in the number of primary and secondary syphilis cases in young women in the late 1980s and early 1990s, largely due to illicit drug use and the exchange of drugs for sex. A concomitant increase in congenital syphilis (Fig. 1) occurred during this period, due to 2 factors: (1) an increase in the number of actual cases and (2) revised reporting guidelines that broadened the definition of congenital syphilis in 1989 so that symptoms of disease or serologic evidence of syphilis in the newborn is not a requirement (ie, birth to a mother who is untreated or inadequately treated can be used as presumptive evidence of congenital syphilis).[1]

Figure 1. Reported cases of congenital syphilis in infants <1 year of age and rates of primary (P) and secondary (S) syphilis in US rose dramatically in 1980s and 1990s due to increase in number of actual cases and to revised reporting guidelines (Kaufman Criteria) that broadened definition of congenital syphilis. Figure courtesy of Centers for Disease Control and Prevention.

While it is established that appropriate treatment of the pregnant woman can prevent congenital syphilis, the major deterrent has been the inability to effectively identify and treat these women. First, the population of women most likely to pass along a syphilis infection to an unborn child often have social and medical problems that interfere with their access to syphilis screening and treatment. Syphilis in pregnancy has been strongly associated with cocaine use, teen pregnancy, low education levels, HIV infection, and underutilization of the health care system[1,2]--all factors that notoriously make medical treatment goals difficult to achieve. In one study that evaluated the epidemiologic risk factors for congenital syphilis, the major contributor was found to be lack of prenatal care.[3]

The stage of infection can also complicate screening. If the woman is tested too early, that is, during the incubation of disease, the test may be falsely negative. That's why women need to be tested for syphilis as soon as the pregnancy is detected and again in the last trimester.

Additionally, determining a penicillin regimen appropriate for both treating a woman during pregnancy and preventing or eradicating syphilis infection of the fetus can be complex. The clinician must consider the stage of maternal infection, the length of fetal exposure to the organism, and the ways in which physiologic changes in pregnancy can alter pharmacokinetics. These treatment decisions may be further complicated in patients who are allergic to penicillin or infected with HIV.

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