Role Of Sonological Fetal Cerebellar Measurement In Gestational Age Determination

Abstract

Sonographic measurement of fetal biparietal diameter is a well accepted predictor of gestational age. However there is a high variability in the calculated gestational age which increases as pregnancy progresses. The estimation of gestational age from individual parameters like the HC, AC, and FL also shows a similar variability. Using all the above parameters this variability can be reduced by 25% to 30 %. There are conditions like oligohydromnios, multiple gestation, breech presentation and intrauterine growth restriction (IUGR) that can alter the shape of the fetal skull which in turn can affect the BPD and increase the variability. The present study is being undertaken to measure the transverse cerebellar diameter (TCD) to validate it as an additional morphological measurement of fetal growth with less variability. The cerebellum and posterior fossa are aligned perpendicular to the plane of maximum extrinsic compression. Hence, they are able to withstand deformation by extrinsic pressure than the parietal bones and can be a more accurate parameter for the determination of gestational age.