Zika in pregnancy — DTM&H MCQ

Correct answer: E — Serial ultrasound monitoring for microcephaly and intracranial calcification

The correct answer is E, serial ultrasound monitoring for microcephaly and intracranial calcification. This woman has a classic Zika prodrome (low grade fever, conjunctivitis, pruritic maculopapular rash) after travel to an endemic area, and first trimester exposure carries the highest risk of congenital Zika syndrome. UK PHE/UKHSA algorithm advises that confirmed or probable maternal infection triggers a follow-up pathway based on repeated fetal ultrasound (typically four-weekly) looking specifically for microcephaly, ventriculomegaly and intracranial calcification, alongside serology and, where indicated, PCR testing. Ultrasound is non-invasive, repeatable across gestation, and is the modality that actually detects the structural brain phenotype that defines fetal Zika damage, unlike karyotyping or biochemical markers which do not identify an infective, non-genetic teratogen. Why the other options are wrong: D. Amniocentesis for fetal karyotype: this investigates chromosomal abnormality, not a viral teratogenic process; Zika-affected fetuses typically have normal karyotype, so this does not assess Zika-specific risk. C. Maternal serum alpha-fetoprotein: this is a marker for neural tube defects and aneuploidy screening, not for congenital viral infection, and has no validated role in Zika risk assessment. B. Fetal MRI at 20 weeks: MRI can supplement ultrasound for equivocal cortical or migrational abnormalities later in pregnancy, but it is not the first-line or serial surveillance tool and a single scan at one time point misses evolving findings that develop over weeks. A. Cordocentesis for fetal IgM: this is an invasive procedure with significant fetal loss risk and is not part of standard Zika evaluation; amniotic fluid PCR, not cordocentesis for IgM, is the recognised invasive test when needed. Key point: serial (not single) ultrasound scanning for microcephaly and intracranial calcification is the mainstay of fetal surveillance after maternal Zika exposure, especially following first-trimester infection.

Reference: UK Health Security Agency (formerly Public Health England), Zika virus: clinical management and algorithm for assessing pregnant women with travel history, gov.uk (https://assets.publishing.service.gov.uk/media/5c6f0039e5274a0eccf6bfbf/Zika_testing_algorithm_for_assessing_pregnant_women.pdf)