Foetal Transcerebellar Diameter (TCD) measurement between 18 and 23 weeks of pregnancy

Background: The measurement of the Transcerebellar Diameter (TCD) is an emerging ultrasound parameter useful for the estimation of gestational age (GA). Objectives: The objectives of the present study included the establishment of baseline TCD values between 18 and 23 weeks of pregnancy, as a basis for predicting gestational age. Other targets included the determination of the correlation between TCD and the actual/predicted gestational ages and the concordance between the actual and predicted gestational ages in the population. Methods: A cross-sectional study was conducted on 488 singleton fetuses during the second-trimester anomaly scan sessions. Transabdominal ultrasound scan measurement of the Transcerebellar Diameter (TCD) was carried out using standard criteria and both TCD, and GA measurements were used to construct nomograms. Chi-square (Goodness-of-fit) was used to evaluate the statistical significance of differences between the observed and expected (predicted) TCD and GA values. The actual gestational age subtracted from predicted gestational age was subjected to Pearson correlation to determine concordance (r). Results: Transcerebellar Diameter ranged between 16.7mm at 18 weeks and 26.7mm at 23 weeks, with a mean value of 18.5+ 0.96mm and 23.1 +1.65mm respectively. There was a positive correlation between TCD and GA (r = 0.85; p