Estimation of gestational age by ultrasound measurement of fetal transcerebellar diameter

Introduction: Transcerebellar diameter (TCD) normogram predicts gestational age (GA) with an accuracy of 94% in the third trimester. The study aims to evaluate the application and accuracy of Transcerebellar diameter in determining the GA of the fetus and Its Correlation. Material and Methods: A cross-sectional prospective study conducted to determine the different antenatal ultrasound examinations were performed in 100 normal healthy pregnant with single fetus women having between 25 and 32 weeks of gestation. Results: Mothers mean GA on ultrasound was 28.4 +/- 0.75 (27-30.2) weeks. The mean fetal biometry parameters including biparietal diameter (BPD) was 73 +/- 2.3 mm (67-80), head circumference (HC) was 264 +/- 8.7 mm (237.8-311), abdominal circumference (AC) was 244 +/- 8.9 mm (226.6-265.9), femur length (FL) was 55 +/- 2.1 mm (49.5-59.6), fetal heart rate was 149 +/- 8.5 beats (121-175). The mean transcerebellar (TCD) measurement was 31 +/- 1.1 mm. The correlation coefficient between the period of gestation and TCD was found to be 0.99 at 27-30 weeks which was statistically significant (P < 0.001) (r > 0.99). Discussion and Conclusion: From the present study, it was observed that the TCD increases linearly with GA. The correlation between GA and the GA by TCD seems to increase from 28 to 30 weeks. There is a good correlation between GA derived from TCD and from established biometric indices like BPD, HC, AC, and femur length.