205: Application of different fetal head circumference normality ranges for the identification of abnormal head growth in Zika infected fetuses in a Colombian Cohort


      To determine the optimal method to assess head circumference in a prospective cohort of Zika virus (ZIKV) infected fetuses during the current outbreak in Barranquilla, Colombia.

      Study Design

      Between December 2015 to July 2016, all patients referred to our center for ZIKV symptoms during pregnancy with themselves or their partners were included in this study (n=214). Monthly fetal ultrasound(US) was performed to assess biometrics and brain development. Head circumference (HC) measurements were compared to Intergrowth21 (IG21), Kurmanavicius, Chervenak, and Hadlock standards. Additionally, they were also compared to a historical cohort (2011-2012) of 772 healthy Colombian patients with normal fetuses used to establish the normality for growth in a comparable cohort. HC measurements were classified if < -2 Z-scores (ZS) and -3 ZS cutoffs.


      From 214 patients, 13 presented with fetal brain anomalies compatible with congenital ZIKV infection by US. Seven cases have RTPCR+ for ZIKV and results from 6 are still pending. All cases presented with a cluster of findings inclusive of microcephaly, ventriculomegaly, callosal dysgenesis, periventricular calcifications, and different degrees of cortical anomalies. 2 cases were found to have clubfeet, and a single case had an isolated finding of a dysgenesis of cerebellar vermis. All 13 affected cases presented with clinical ZIKV symptoms or partner exposure by 17 weeks (12.15+4.36 weeks). The median age of US findings was 28.6+5.12 weeks, and microcephaly was concurrently observed in some but not all cases (71.4 and 71.4% had HC<2ZS and <3ZS with IG21 standards; 71.4 and 57.1% with Kurmanavicius; 71.4 and 28.6% with Chervenak; 71.4 and 50% with Hadlock and 71.4 and 64.3% using Colombian standards for <2ZS and <3ZS respectively).


      Based on these results in the largest reported ZIKV-exposed referral cohort to date, the use of 2ZS below the mean as a cutoff to identify those fetuses at risk of developing congenital ZIKV with significant brain malformations should be considered. Different reference standards showed similar detection rates for this cutoff, although malformations were detected prior to microcephaly. These findings suggest that detailed fetal neurosonography improves detection, and should be performed in patients at risk.