ISOLATED LARGE 4TH VENTRICLE IN EARLY-PREGNANCY - A POSSIBLE BENIGN TRANSIENT PHENOMENON

Twenty-one fetuses with an enlarged fourth ventricle were detected by ultrasound at 13-16 weeks' gestation. No other central nervous system anomalies were observed and a normal size fourth ventricle was noted i n all cases on follow-up scans at 22-23 weeks' gestation. Five fetuses had associated structural anomalies: a single umbilical artery in two cases, non-septated cystic hygroma in two cases and ventricular septa l defect in one fetus. All fetuses had a normal brain sonogram after d elivery. Nineteen newborns who were followed up to the age of one year had no developmental problems. It is concluded that an isolated enlar ged fourth ventricle might be a physiological variant in early fetal l ife. (C) 1998 John Wiley & Sons, Ltd.