A 30-year-old woman presents to your clinic at 26 weeks gestation. She is worried because 24 hours ago, she came in contact with a child, who had chickenpox. Her pre-pregnancy IgG against chickenpox was negative, and she missed her prenatal chickenpox vaccine. On examination, she is asymptomatic. Which one of the following would be the next best step in management? 

1. Check varicella zoster virus IgM level.
2. Give varicella vaccine.
3. Check IgG level.
4. Give varicella zoster immunoglobulin (VZIG).
5. No action is needed because she is asymptomatic.

When dealing with a preganant woman with possible exposure to varicella zoster virus (VZV), like contact with someone with chicken pox,  the very first step in management is to determine if she has immunity against the virus. This is performed by checking the IgG levels VZV. If VZV IgG is negative the management depends on the time from exposure: 

1- If still within the 96 hours post-exposure the next best step would be VZV immuniglobulin (VZIG). 

2- If more than 96 hours has passed since exposure, VZIG would be of no use, but consder to prophylactically treat the following groups of women with aciclovir (preferred) or valaciclovir (second choice): 

• Women in the second half of pregnancy 
• Women with as a history of an underlying lung disease
• Women who are immunocompromised
• Smoker women

he patient has no history of chickenpox or vaccination against VZV, and a pernatal IgG has been negative. For this patient serology is not required. Since she has presented within 96 hours of exposure, the next step in management would be treating her with prophylactic IVIG (VZIG).

(Option A) Measuring IgM level could be helpful if there was an atypical presentation of varicella zoster infection. This patient is completely asymptomatic at this stage; hence, checking IgM level would be unnecessary.

(Option B) Chicken pox vaccine is a live attenuated vaccine and contraindicated in pregnancy.

(Option C) This patient has a recent negative IgG level and has had no infection to make her immune. Her IgG is negative and no IgG measurement is required.

(Option E) This patient needs follow-up for possible infection. Taking no action is incorrect.

NOTE - given the fact that she is in the second half of her pregnancy, the correct answer would have been treating her with an anti-viral agent (aciclovir or valeciclovir) if she had presented after 96 hours from exposure.