Type-specific screening for asymptomatic herpes infection in pregnancy: a decision analysis.

OBJECTIVE: To evaluate the merits of serum screening for herpes simple virus (HSV) in pregnant women with no history of prior HSV infection.

DESIGN: Clinical decision analysis.

POPULATION: Hypothetical cohort of pregnant women in first trimester with no clinical history of HSV infection.

METHODS: We used decision analysis techniques to compare three strategies for antepartum screening for HSV in women with no history of infection: (1) universal screening; (2) targeted screening in women estimated to be at high risk for infection; and (3) current care (no screening). For the screening strategies, we considered screening at 35 weeks of gestation, with prophylactic antiviral therapy for seropositive women. For all women, we assumed caesarean delivery in the setting of symptomatic infection at delivery. We performed a literature review of English-language publications to derive probability estimates for the rate of HSV seropositivity in asymptomatic pregnant women, and the risks of symptomatic HSV infection and asymptomatic shedding at the time of delivery. We determined the modification of rates of viral shedding, symptomatic lesions and caesarean section with the use of prophylactic suppression therapy for seropositive women based on available data. We chose neonatal herpes with severe sequelae, neonatal death, as well as caesarean delivery as clinically relevant outcomes.

MAIN OUTCOME MEASURES: Number of cases of neonatal death, neonatal HSV with severe sequelae, neonatal HSV with moderate sequelae, patients screened, patients treated and caesarean section with each strategy.

RESULTS: Universal maternal screening reduced the total number of deaths and severe sequelae secondary to neonatal HSV. Universal screening required treatment of 3849 women to prevent one case of neonatal death or disease with severe sequelae from HSV. Targeted screening of high risk women treatment of 2277 women to prevent one death or case of severe disease. Universal screening reduced the rate of neonatal HSV attributable to recurrent HSV by 79.3%. Caesarean delivery was reduced with both screening strategies. We used one-way sensitivity analyses to evaluate the robustness of our model.

CONCLUSIONS: Maternal screening reduced the number of cases of neonatal HSV. Screening also reduced the rate of caesarean delivery. However, employing universal screening will likely result in a significant expenditure of medical resources because the number needed to treat to avert a single case of neonatal herpes is high.