Cerebellar Measurements with Ultrasonography in the Evaluation of Fetal Age

The use of ultrasonography has significantly improved the evaluation of fetal growth and development and has permitted prenatal diagnosis of a variety of congenital malformations.Campbell et al in (1968) studied fetal cephalometry in the second trimester and determined that the fetal head can be measured from 13 week of pregnancy2. BinholzJ.C(1982) studied the new born cerebellar size both in full term and in preterm babies. To estimate the gestational age of the fetus by measuring transcerebellar diameter in normal and Intrauterine growth retarded pregnancies by ultrasonography and to evaluate whether the transcerebellardiameter or other parameters like biparietal diameter, head circumference, abdominal circumference is accurate for the gestational age. Aims and Objective:  To evaluate the usefulness of transcerebellar diameter as against the conventional parameters of biparietal diameter and femur length in normal pregnant mother between 15 to 40 weeks.  To evaluate the usefulness of transcerebellar diameter in antenatal diagnosis of intrauterine growth retardation.  To derive nomograms for estimating the gestational age of the fetus from the measured transcerebellar diameter.  To evaluate morphological abnormalities. Method: Ultrasonographic estimation of gestational age by transcerebellar diameter was done in normal and intrauterine growth retarded pregnancies in 100 pregnant women(80 normal pregnancies and 20 IUGR pregnancies) between 15 to 40 weeks of gestation. Result: The study was conducted in the department of radiodiagnosis in Adichunchangiri Institute Of Medical Sciences.Out of the 100 patients who were scanned for the trabscerebellar diameter and other parametersbiparietal diameter, head circumference, abdominal circumference and femur length 80 were of normal pregnancies and 20 were with intrauterine growth retardation. The results obtained were that the patients with normal pregnancy and those with IUGR had no statistically difference with the age and parity. It showed that in 17 out of 20 patients the TCD measurements were within the normal range(between 5 th and 95 percentile) and only in 3 patients it was less than 5 percentile but BPD and FL were less than 5 percentile in 18 out of 20 patients and AC,HC measurements were less than 5 percentile in all the 20 patients. This difference was statistically significant(P=0.0001),that is TCD measurements were within the normal range in significantly higher number of patients than other ultrasonic measurements. Conclusion: Transcerebellar diameter is the better parameter for gestational age assessment than BPD and FL as it is not fraught with the problems in the measurements commonly encountered in BPD and FL and also it is an added advantage in cases of IUGR pregnancies and also can be used as a single growth parameter to predict the gestational age using various obtained formulas and nomograms both in normal and IUGR pregnancies