Objective: To determine the normal appearance and development of the fetal cerebellar vermis using mid-sagittal planes obtained by transvaginal sonography.
Subjects and methods: A total of 101 fetuses were evaluated by transvaginal sonography between 21 and 39 weeks of gestation. The mid-sagittal antero-posterior and cranio-caudal vermian diameters, circumference and surface area were measured and calculated. Nomograms were produced.
Results: The vermis was observed in 96% of the cases and all the measurements were performed in 92%. The vermis grows in a linear fashion throughout pregnancy. The growth pattern correlates well with gestational age, biparietal diameter, head circumference and transverse cerebellar diameter.
Conclusion: Transvaginal sonography is a valuable tool in the study of the fetal vermis during the second half of pregnancy. Knowledge of its normal appearance may help identify developmental anomalies and enable accurate prenatal counseling.
Copyright 2001 John Wiley & Sons, Ltd.