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Question 732
Obstetric infection → Viral
Classification
Question
SSBAQuestion Header
VZV IgG threshold for post-exposure prophylaxis
Question Stem
A pregnant woman with no evidence of immunosuppression has significant exposure to chickenpox. Her VZV IgG concentration is 80 mIU/ml. What is the most appropriate management?
Options
A
Reassure her that no further action is required
B
Offer post-exposure prophylaxis
C
Repeat VZV IgG only if she develops a rash
D
Arrange immediate amniocentesis for VZV PCR
E
Give varicella vaccine during pregnancy
Explanation
Following significant exposure, PEP should be offered to a pregnant woman whose VZV IgG is negative or below 100 mIU/ml. A concentration of 80 mIU/ml therefore meets the criterion for PEP. The guideline distinguishes this from immunosuppressed pregnant women, for whom a higher threshold is used when determining susceptibility.
Option Validity
A) 80 mIU/ml is below the threshold used to determine whether PEP should be offered.
C) management should not be deferred until clinical chickenpox develops.
D) amniocentesis is not used to determine maternal susceptibility after exposure.
E) varicella vaccination is not administered during pregnancy.
Further Reading
RCOG Green-top Guideline No. 13, Chickenpox in Pregnancy, section 4.3.