Acyclovir Reduces Herpes Lesions, Cesarean Section Rates

OB/GYN News, Oct 15, 2001 by Kathryn DeMott

QUEBEC CITY -- Prophylactic acyclovir given late in pregnancy significantly reduces herpes simplex virus lesions and lowers C-section rates for herpes, Dr. D. Heather Watts said at the annual meeting of the Infectious Diseases Society for Obstetrics and Gynecology.

Currently, 20%-30% of pregnant women in the United States are positive for herpes simplex virus type 2 (HSV-2), and it's recommended that women with genital lesions at the time of delivery undergo C-section, she said.

In a study of 170 HIV-negative women with at least one symptomatic recurrence of genital herpes simplex virus (HSV) in the past year, 4 patients (5%) treated with acyclovir and 12 patients (15%) who received placebo had lesions at delivery, a significant difference.

Rates of C-sections for herpes were 3% among patients in the acyclovir group and 11% for women in the placebo group, a difference that was not quite statistically significant.

Eighty-seven women were randomized to take acyclovir, 400 mg t.i.d., starting at 36 weeks' gestation until delivery, while the remaining 83 women received a placebo.

All the women kept daily symptom diaries and obtained daily perineal and cervicovaginal specimens at home for culturing and DNA detection by polymerase chain reaction (PCR) analysis, explained Dr. Watts of the University of Washington, Seattle, and the University of British Columbia, Vancouver.

Those women taking acyclovir were significantly less likely than those on placebo to obtain positive genital cultures during pregnancy (11% vs. 40%). Likewise, PCR analysis showed that HSV DNA was significantly less common among women taking acyclovir than in women taking placebo (36% vs. 60%).

The rate of PCR positivity within 2 days of delivery was 2% for the acyclovir group versus 34% for the placebo group.

Obstetric management was at the discretion of the attending physician who was blinded to group assignments.

Over the years, recruitment for the study became virtually impossible due to the widespread use of acyclovir in the Seattle-Vancouver region, she said. As a result, the study therefore was not powered to show a statistically significant difference in C-section rates among the groups.

Still, the study findings indicate a trend that is echoed in similar studies of patients with histories of symptomatic recurrences, Dr. Watts noted. Other studies have shown lower C-section rates in the acyclovir group that were statistically significant.

But when it comes right down to it, acyclovir probably won't make much of a dent in the overall rate of cesarean sections for all women. Only about 5% of all pregnant women have a history of symptomatic recurrent herpes-and are therefore candidates for acyclovir-compared with about 30% who are unknowingly antibody positive.

And among women with a history of symptomatic herpes, very few actually wind up requiring C-section for lesions at the time of delivery. So while acyclovir is of some benefit for this small high-risk group, it isn't likely to lower the overall C-section rate by very much.

"I think this therapy would probably be the most beneficial among women with primary herpes during pregnancy because of the increased risk of asymptomatic shedding among those women. But we need to study that carefully," she said.

The therapy was well tolerated and is not associated with any differences in neonatal outcomes.