Normal Intracranial Translucency Values During the First Trimester of Gestation in a Latin American Population

Objectives: The purpose of this study was to establish intracranial translucency reference values in healthy fetuses from a Latin American population.

Methods: This work was a cross-sectional retrospective correlational study. A review of sonographic reports from women between gestational ages of 11 weeks and 13 weeks 6 days at 2 health institutes in Bogota, Colombia, whose fetuses had a crown-rump length of 45 to 84 mm was conducted between January 1, 2010, and December 31, 2012. Women with multiple fetuses or with a deceased fetus were excluded.

Results: Data corresponding to 1520 obstetric sonographic examinations were included in the statistical analysis. The crown-rump length was between 45 and 84 mm, with a median of 65 mm (interquartile range, 58-73 mm). The median intracranial translucency was 1.7 mm (interquartile range, 1.4-2.2 mm). Different percentiles (1st, 5th, 10th, 25th, 50th, 75th, 90th, 95th, and 99th) were established for each crown-rump length value. A correlation between crown-rump length and intracranial translucency was found, which seemed to be linear. The intracranial translucency value was not significantly correlated with the frontomaxillary angle but was correlated with nuchal translucency, nasal bone length, and metopic suture length.

Conclusions: We present normal intracranial translucency values in the first trimester of single gestations with live fetuses in a Latin American population. These values are similar to those described in other populations. The intracranial translucency value was linearly correlated with crown-rump length in fetuses between gestational ages of 11 weeks and 13 weeks 6 days, which is consistent with previous publications, although these data cannot be interpreted independently.