Ultrasonographic observations of the fetal brain in the first 100 pregnant women with Zika virus infection in Trinidad and Tobago

Objective: To evaluate the fetal brain in pregnant women infected with Zika virus in a limited-resource setting. Methods: In an observational study in Trinidad and Tobago, 100 pregnant women infected with Zika virus who were referred for fetal medicine services provided by a single clinician were enrolled from March 31 to September 2, 2016. Two-dimensional ultrasonography was undertaken. Results: The women were aged 17-41 years (mean 27.5 +/- 5.7). Six cases of fetal brain abnormalities consistent with Zika infection were detected before 26 gestational weeks. The gestational period at infection and time of presentation ranged, respectively, from 7(+3) to 16(+0) weeks and from 23(+2) to 25(+5) weeks. In all cases, centiles of the biparietal diameter and head circumference decreased progressively over time to below the third centile. The skull contour appeared irregular, owing to collapse or overlap of the fetal skull bones. In four cases, brain anomalies were not obvious on the transabdominal scan but were diagnosed on the transvaginal scan. In a further two cases, brain abnormalities presented after 26 weeks of gestation. Conclusion: Overall, 8.0% of women infected with Zika virus had fetuses with brain abnormalities suggestive of Zika congenital syndrome. Six cases were detected before 26 weeks and two cases after 26 weeks.