DR A PARIMALA,DR ROSELIN,DR SIRISHA,DR. MATHANGI
DOI: https://doi.org/Background: Accurate estimation of gestational age (GA) is essential in obstetrics to guide decisions related to delivery and management, especially in high-risk pregnancies. While conventional ultrasound parameters such as biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), and femur length (FL) are widely used, each has limitations in the third trimester. Transcerebellar diameter (TCD) has been proposed as a more consistent alternative due to its resistance to positional and growth-related anomalies.
Methods: A prospective observational study was conducted on 204 singleton pregnancies between 29 and 40 weeks gestation. Each participant underwent two ultrasonographic evaluations measuring BPD, HC, AC, FL, and TCD. Postnatal gestational age was confirmed using Ballard scoring. Correlations were analyzed using Pearson coefficients and regression models were derived for TCD-based GA prediction.
Results: TCD demonstrated the highest correlation with GA (r = 0.921 at 29–35 weeks and r = 0.957 at 35–40 weeks; p < 0.0005). Regression analysis yielded predictive equations with R² values of 0.849 and 0.915 respectively. TCD values were consistent with Indian normative data and remained reliable even in growth-restricted cases.
Conclusion: TCD is a robust and accurate parameter for estimating gestational age in the third trimester. It should be incorporated into routine fetal biometry, particularly when LMP is uncertain or conventional parameters are compromised.
