Pregnancy and prevention
During pregnancy, 2% of women will acquire HSV, and 70% of these women will be asymptomatic.4,7 Approximately one-third to one-half of neonatal infections are caused by HSV-1.8 The most devastating complication of HSV infection in pregnancy is transmission to the newborn. Neonatal herpes is defined as the diagnosis of an HSV infection in a neonate within the first 28 days of life. The disease spectrum varies widely, and early recognition and treatment can substantially reduce the degree of morbidity and mortality associated with systemic infections.
HSV infection limited to the skin, eyes, and mucosal surfaces accounts for 45% of neonatal infections. When this condition is promptly recognized, neonates typically respond well to intravenous acyclovir, with prevention of systemic progression and overall good clinical outcomes. Infections of the central nervous system account for 30% of infections and are more difficult to diagnose due to the nonspecific symptomatology, including lethargy, poor feeding, seizures, and possible absence of lesions. The risk for death decreases from 50% to 6% with treatment; however, most neonates will still require close long-term surveillance for achievement of neurodevelopmental milestones and frequent ophthalmologic and hearing assessments.8,9 Disseminated HSV accounts for 25% of infections and can cause multiorgan failure, with a 31% risk for death despite treatment.5 Therefore, the cornerstone of managing HSV infection in pregnancy is focusing clinical efforts on prevention of transmission to the neonate.
More than 90% of neonatal herpes infections are acquired intrapartum,4 with 60% to 80% of cases occurring in women who developed HSV in the third trimester near the time of delivery.5 Neonates delivered vaginally to these women have a 30% to 50% risk of infection, compared to a <1% risk in neonates born to women with recurrent HSV.1,5,10 The discrepancy in infection risk is thought to be secondary to higher HSV viral loads after an initial infection as opposed to a recurrent infection. Furthermore, acquisition of HSV near term does not allow for the 6 to 12 weeks necessary to develop antibodies that can cross the placenta and provide neonatal protection. The risk of vertical transmission is approximately 25% with an initial-nonprimary episode, reflecting the partial protection afforded by antibody against the other viral serotype.11
Prophylactic therapy has been shown to reduce the rate of asymptomatic viral shedding and recurrent infections near term.7 To reduce the risk of intrapartum transmission, women with a history of HSV prior to or during pregnancy should be treated with acyclovir 400 mg orally 3 times daily starting at 36 weeks of gestation. When patients present with rupture of membranes or labor, they should be asked about prodromal symptoms and thoroughly examined. If prodromal symptoms are present or genital lesions identified, patients should undergo cesarean delivery.12 Some experts also recommend cesarean delivery for women who acquire primary or initial-nonprimary HSV infection in the third trimester due to higher viral loads and potential lack of antibodies at the time of delivery.8,12 However, this recommendation has not been validated by a rigorous prospective randomized clinical trial. When clinically feasible, avoidance of invasive fetal monitoring during labor also has been shown to decrease the risk of HSV transmission by approximately 84% in women with asymptomatic viral shedding.12 This concept may be extrapolated to include assisted delivery with vacuum or forceps.
Universal screening for HSV infection in pregnancy is controversial and widely debated. Most HSV seropositive patients are asymptomatic and will not report a history of HSV infection at the initial prenatal visit. Universal screening, therefore, may increase the rate of unnecessary cesarean deliveries and medical interventions. HSV serology may be beneficial, however, in identifying seronegative pregnant women who have seropositive partners. Two recent studies have shown that 15% to 25% of couples have discordant HSV serologies and consequently are at risk of acquiring primary or initial-nonprimary HSV near term.4,5 These couples should be counseled concerning the use of condoms in the first and second trimester (50% reduction in HSV transmission) and abstinence in the third trimester.5 The seropositive partner also can be offered suppressive therapy, which provides a 48% reduction in the risk of HSV transmission.4 Ultimately, the difficulty lies in balancing the clinical benefits and cost of asymptomatic screening.11
CASE Resolved
The patient should be counseled that HSV infection rarely affects the fetus in utero, and transmission almost always occurs during the delivery process. This patient should receive prophylactic treatment with acyclovir beginning at 36 weeks of gestation to reduce the risk of an outbreak near the time of delivery. ●