Herpes Zoster in Pregnancy - Exam Notes (MD Dermatology)

1. Key Concept (High-yield line for viva/theory)

2. Epidemiology/Pathogenesis (brief)

• HZ in pregnancy is uncommon (pregnancy itself is not a major risk factor for zoster - age and immunosuppression are the main drivers).
• Clinical picture is identical to non-pregnant patients: unilateral, dermatomal, painful vesicular eruption from reactivated ganglionic VZV.

3. Maternal Risks

• Same complications as general population, but pregnancy warrants closer surveillance:
  • Post-herpetic neuralgia (PHN)
  • Secondary bacterial infection
  • Ophthalmic zoster (V1 dermatome) - risk of keratitis, uveitis
  • Ramsay Hunt syndrome (facial palsy)
  • Disseminated HZ (>3 dermatomes/generalized) - seen mainly if immunocompromised (HIV, on immunosuppressants) - can progress to pneumonitis, hepatitis, encephalitis; mortality 5-10% even with treatment.

4. Fetal/Neonatal Risk (clarify vs varicella)

• Maternal HZ during pregnancy -> negligible risk of congenital varicella syndrome (mother is already seropositive, so no transplacental primary viremia).
• Exception - peripartum timing: if HZ (or exposure) occurs very close to delivery, or if the mother is severely immunocompromised, neonatal risk rises.
  • Neonates whose mother had HZ onset 5 days before to 2 days after delivery should receive VZIG and be observed, since maternal antibody may not have transferred adequately yet.
• Contrast: primary varicella in first 20 weeks carries ~2% risk of fetal varicella embryopathy (limb hypoplasia, cicatricial skin scarring, microcephaly, eye defects, IUGR); varicella in the 5 days before to 2 days after delivery carries high risk of severe neonatal varicella (no maternal antibody transferred).

5. Diagnosis

• Primarily clinical (dermatomal vesicular rash with pain).
• Confirm with PCR of vesicle fluid if atypical presentation (e.g., genital zoster-like lesions - must differentiate from HSV; molecular testing recommended per recent literature) - Archives of Dermatological Research, 2024 (Singal et al., PMID 38489022).

6. Management

A. Antiviral therapy

• Acyclovir is the drug of choice in pregnancy - it has the most safety data, is FDA pregnancy Category B, and no increased risk of major birth defects has been shown in large registries/observational studies.
  • Fitzpatrick's Dermatology: "Acyclovir given in late pregnancy..." is used without evidence of teratogenicity; pregnancy category B for acyclovir in the systemic antiviral table.
  • Goodman & Gilman's: "No excess frequency of congenital abnormalities has been recognized in infants born to women exposed to acyclovir during pregnancy."
  • Harrison's 22nd ed: Acyclovir can be used in all stages of pregnancy, and in breastfeeding mothers (excreted in breast milk but considered compatible).
• Dose: Oral acyclovir 800 mg five times daily for 7-10 days (standard HZ regimen), started ideally within 48-72 hours of rash onset for maximum antiviral efficacy.
• IV acyclovir (10 mg/kg every 8 h) is indicated for:
  • Disseminated HZ
  • Ophthalmic/trigeminal zoster with ocular involvement
  • Immunocompromised patients
  • Any evidence of visceral involvement (pneumonitis, hepatitis, encephalitis)
• Valacyclovir/Famciclovir: Limited pregnancy safety data compared to acyclovir; famciclovir specifically "not recommended for use in pregnancy" per some sources (Rosen's Emergency Medicine) due to limited experience - acyclovir remains preferred first-line.

B. Analgesia

• Standard stepwise pain control; use pregnancy-safe agents:
  • Paracetamol first-line.
  • Avoid NSAIDs, especially in the third trimester (risk of premature ductus arteriosus closure, oligohydramnios).
  • Neuropathic agents (gabapentin, amitriptyline) used with caution - weigh benefit vs limited pregnancy safety data; reserve for refractory pain/PHN.
  • Topical lidocaine 5% patch is a reasonable, low-systemic-absorption option for localized pain.
• Corticosteroids: may shorten acute pain/erythema duration in some cases but do not prevent PHN; use cautiously, generally avoided as first-line in pregnancy unless clearly indicated (e.g., facial palsy/Ramsay Hunt, severe inflammation).

C. Immunoglobulin (VZIG) - note the different indication for HZ vs varicella

• VZIG is mainly indicated for susceptible (seronegative) pregnant women exposed to varicella, not for treating maternal HZ itself.
• In HZ specifically, VZIG is reserved for the neonate when maternal zoster occurs peripartum (5 days before to 2 days after delivery), since antibody transfer may be inadequate.

D. Special situations

• Disseminated/severe HZ or immunocompromised mother: admit, IV acyclovir, multidisciplinary care (dermatology + obstetrics + infectious disease), fetal monitoring.
• Ophthalmic zoster: ophthalmology referral, IV/oral acyclovir plus topical ophthalmic antivirals as needed.
• Genital zoster-like lesions: differentiate from genital HSV via PCR - management (mode of delivery, neonatal risk assessment) differs by etiology.

E. Vaccination (counseling point, not treatment of active episode)

• Live-attenuated varicella vaccine and both zoster vaccines (ZVL/Zostavax, RZV/Shingrix) are contraindicated during pregnancy and should not be given within 30 days of a planned pregnancy.
• Seronegative postpartum women should be vaccinated before hospital discharge.
• No current ACIP recommendation for RZV use in pregnancy - defer until postpartum (Goldman-Cecil Medicine).

F. Delivery and breastfeeding

• HZ itself is not an indication for cesarean delivery or isolation of mother from infant (lesions should be covered if actively vesicular, standard contact precautions until crusted).
• Acyclovir is considered compatible with breastfeeding.

7. Summary Table (quick recall for exam)

References

• Fitzpatrick's Dermatology, Vol 1-2 - Herpes Zoster chapter, Antiviral Agents chapter
• Creasy & Resnik's Maternal-Fetal Medicine - Varicella-Zoster Virus section
• Harrison's Principles of Internal Medicine, 22nd ed - HSV/VZV in pregnancy
• Goodman & Gilman's Pharmacological Basis of Therapeutics - Acyclovir untoward effects
• Dermatology, 2-Volume Set, 5e - Systemic antiviral agents in pregnancy
• Singal A, Schwartz RA, Bhate C. "Herpes zoster infection in pregnancy: features and consequences." Arch Dermatol Res. 2024. PMID: 38489022
• Ion A, Orzan OA, Bălăceanu-Gurău B. "Varicella Zoster Virus Infection and Pregnancy: An Optimal Management Approach." Pathogens. 2025. PMID: 40005527