Obgyno Wino Podcast Episode 51 - Management of Genital Herpes in Pregnancy
"Truth is within ourselves; it takes no rise From outward things, whate'er you may believe. There is an inmost centre in us all, Where truth abides in fulness; and around, Wall upon wall, the gross flesh hems it in, This perfect, clear perception - which is truth. A baffling and perverting carnal mesh Binds it, and makes all error: and to KNOW Rather consists in opening out a way Whence the imprisoned splendour may escape, Than in effecting entry for a light Supposed to be without." - Robert Browning, From "Paracelsus"
PB#220 - Published May 2020
1. Herpes simplex virus (HSV) is transmitted directly from lesions to mucosa or open skin: this includes cold sores to mucosa, active lesions on the skin, or ulcers on or inside the genitals.
2. Infection of babies generally occurs during passage of the newborn through mom's GU tract, not in-utero.
3. Neonatal herpes infections carry relatively high mortality and morbidity.
4. Active or recurrent infections in pregnancy should be treated with antiviral therapy. Suppression therapy should be given to all women with history of HSV starting at 36 wga and continued until birth.
5. Women who have active genital HSV infections manifested as active lesions or prodromal vulvar symptoms at the onset of labor should be counseled against vaginal birth.
First...a primer on the herp'
- Herpes: double-stranded DNA virus
- two major strains: HSV-1 and HSV-2
- HSV-1: causes herpes labialis (cold sores), gingivostomatitis (similar to canker sores), and keratoconjunctivitis
- HSV-2: causes genital herpes (however, among young people HSV-1 is increasingly becoming culprit for genital lesions, too)
- virus is transmitted through breaks in the skin or through mucosa
- incubation period - that is, the symptom-free period after infection - ranges from 2-12 days
- during this time, it replicates and finds its way to sensory neurons
- eventually, it creeps up these neurons to lay wait in dorsal root ganglia for a prime opportunity in the future to reemerge and cause destruction and chaos
- as long as your immune system - both humoral and cellular components - is functioning on all cylinders, the herpes virus remains dormant
- antibodies to HSV will be identifiable in the blood w/in 2-3 weeks of infection
i. primary infection: virus is detected by PCR after culturing a lesion, no antibodies detected
ii. non-primary first episode infection: virus of one strain (e.g. HSV-1) detected by PCR after culturing a lesion, and antibodies are detected of a different strain (e.g. HSV-2)
iii. recurrent infection: virus of a particular strain are detected by PCR after culturing a lesion along with antibodies for that same strain
How common is herpes?
- true incidence isn't known as most people who are infected with HSV are unaware that they have contracted the virus
- for those who do, only 5-15% report it
- 1.6 million new HSV-2 cases annually in the U.S.
- prevalence of HSV-2 among young people in the U.S. is 50 million
- in a large, national serologic study, 20% of women had antibodies to HSV-2 ("seropositive")
- most monogamous couples have already transmitted it to one another, but 10% of women who are HSV-2 seronegative have seropositive partners, meaning there's a risk for primary infection in pregnancy
- if a pregnant woman has history of genital herpes, 75% chance of at least one recurrence during pregnancy and 15% will have prodromal symptoms or lesions at delivery
What's the risk of transmission to the baby? Is it lethal?
- the baby gets infected through the mom (they exchange a lot of fluids), but ACTUALLY, the virus almost exclusively spreads with passage of the infant through the maternal GU tract (yes: in-utero and postnatal infections are rare)
- higher risk of vertical transmission with primary outbreak (40-80%), thought to be due in part to less transplacental transmission of HSV-2 antibodies
- before widespread testing became available, 80% of infected infants were born to women with no reported history of HSV infection
- incidence of neonatal herpes is 1200-1500 cases annually (25% disseminated disease; 30% confined to CNS; 45% confined to skin, eyes, or mouth)
- of kids w/ infection confined to CNS, mortality rate is 5%; of kids with disseminated disease, mortality rate is 30%
- 20% of survivors of neonatal herpes have long-term neurologic damage
- primary maternal herpes infections are more commonly associated with severe neonatal findings such as chorioretinitis, microcephaly, and skin lesions (compared to recurrent infections)
- no evidence of increased risk of SAB
How do I test for it?
- cultures of primary lesions are more likely to yield a positive result than cultures of recurrent lesions or healing lesions (80% versus 40%) --> low sensitivity, but high specificity (positive result can be trusted)
- how to test: unroof a vesicle, swab the fluid that drains out, send it to the lab for culture/PCR, then grab a snack and wait a few days
- if your patient has suspicious lesions but the PCR testing is negative, you may consider getting serologies to look for antibodies
- if they have HSV-2 antibodies, they likely have genital herpes because HSV-2 is not commonly seen in non-genital herpes
- if they have HSV-1 antibodies, they may have genital herpes, but they may also just have oral herpes, as HSV-1 can be implicated in genital herpes or non-genital herpes
- serologies can help distinguish between primary and recurrent infection, but first-episodes are nearly impossible to distinguish
Should I screen everybody for herpes in pregnancy?
- No. It's not cost effective because, "even for women with a known history of genital herpes, symptomatic viral shedding during the antepartum period does not predict asymptomatic shedding at delivery"
When is vaginal birth contraindicated?
- if a patient reports vulvar burning/pain or has active lesions of the vulva, vagina, or cervix, vaginal birth is contraindicated, and c-section should be recommended
- c-section may also be considered for women who experienced a primary or non-primary first episode infection in the 3rd trimester even if no active lesions or prodromal symptoms given the prolonged shedding phase w/ these infections
- 1.2% risk of transmission to neonate with c-section; 7.7% risk of transmission with vaginal birth (if active lesions or symptoms)
- membrane status or length of ROM (if ruptured) are irrelevant
- c-section is not recommended for herpes lesions outside of the vulva, vagina, or cervix, just cover them up well during labor and birth
What if a patient presents with PPROM and active lesions?
- probably best to keep her pregnant due to the consequences of prematurity
- treat with antiviral, give latency abx, and initiate corticosteroids
- if active labor ensues, follow same rules as you would for a term pregnancy
What if my patient has a history of HSV but no active lesions, can I still use all of my transcervical gadgetry in labor?
- Yes, assuming you've consented the patient
Can a woman with active HSV still breastfeed?
- Yes, given there are no lesions on the breast
- acyclovir is approved in breastfeeding