Chaoui R, Benoit B, Entezami M, et al. - Researchers measured choroid plexus (CP) size in comparison to head size in normal fetuses and compared this in fetuses with open spina bifida (OSB). In addition, they quantified the subjective sign of a ‘dry brain’. For this retrospective study, they assessed ultrasound images obtained during first-trimester screening between 11 and 13 weeks of gestation in 34 fetuses with OSB and 160 normal fetuses. Images in the transventricular axial plane of the fetal head were retrieved from the hospital databases. In the normal fetuses, they observed an increase in the CP area, while a decrease in the ratios of CP area to head area and the CP length to occipitofrontal diameter with increasing crown–rump length. The CPs filled the entirety of the head giving the impression of a dry brain in 30 of the 34 (88%) fetuses with OSB. During a routine first-trimester ultrasound examination, the dry brain sign is easily visualized while measuring the biparietal diameter, and can be quantified by comparing the size of the CPs to the head size. They recommend considering this observation as a hint to prompt the examiner to assess thoroughly the posterior fossa and spine until confirmation of the usefulness of this sign in screening for OSB could be done in prospective data.