Fetal transverse cerebellar diameter measurements in normal and reduced fetal growth

Objectives To establish the increase in fetal transverse cerebellar diamete r (TCD) relative to gestational age during normal and restricted fetal grow th to determine the significance of TCD and TCD/AC relationship in predicti ng. fetal outcome as expressed by perinatal mortality. Design A retrospective cross-sectional study. Subjects Three hundred and sixty normally developing fetuses between 17 and 34 weeks of gestation end 73 growth-restricted fetuses between 24 and 34 w eeks of gestation. Methods Ultrasonographic measurements included head circumference (mm), abd ominal circumference (mm) and transverse cerebellar diameter (mm). A gestat ional age-related normal reference chart was produced for TCD. Results Statistically significant relationships between transverse cerebell ar diameter and gestational age, abdominal circumference and head circumfer ence were found. The normal fetal TCD exhibited a more than twofold increas e in size during the second half of pregnancy. Twenty-six per cent of the s mall-for-gestational age (SGA) fetuses displayed a reduced TCD and 82% of t he SGA fetuses demonstrated raised TCD/AC values. No statistically signific ant difference in perinatal mortality ol birth weight was found between the subsets of growth-restricted fetuses with reduced or normal TCD; or betwee n the subsets with normal or raised TCD/AC values. Conclusions In the normally developing fetus the TCD increases with advanci ng gestational age. Increased TCD/AC values are suspicious of fetal growth restriction. The perinatal mortality in growth-restricted fetuses with a sm all cerebellum is increased twofold over that of other fetuses.