Background: Routine sonographic examination is the cornerstone in estimation of gestational age (GA) and management of pregnancy, using Biparietal diameter (BPD), femur length (FL) and Abdominal circumference (AC) ،but there are limitations with using such parameters. fetal cerebellum exhibits a progressive growth throughout the gestation period. So, it is an organ capable of providing information on the prediction of gestational age during the pregnancy this study has evaluated the accuracy of trancerebellar diameter (TCD) over other parameters of gestational age between 30-40 weeks.
Aim: The study aims to evaluate the accuracy of TCD in singleton gestation as an accurate parameter compared to other parameters (Fl, BPD, AC) and Hadlock equation in determining gestational age in normal pregnant woman and normal fetus.
Materials and Methods: This cross-section study was conducted on 100 pregnant women between 30 to 40 weeks of gestational age who attended the antenatal care in the outpatient clinic at Ain-Shams university maternity hospital in the period from September 2018 to September 2019. The whole patients were fulfilling the inclusion and exclusion criteria and counseled for the study and then ultrasound examination and measurements of the TCD, BPD, FL and AC were recorded, GA by different parameters (TCD, FL, BPD and AC) and GA by Hadlock were compared to GA by last menstrual period (LMP).
Results: In our results the TCD was accurate within 1 week in 91% of the cases and was accurate within 3 days in 59% of the cases. While the FL was accurate within 1 week in 82% of the cases and was accurate within 3 days in 51% of the cases. The BPD was accurate within 1 week in 70 % of the cases and within 3 days in 39% of the cases. Finally, the AC was accurate within 1 week in 65 % of the cases and within 3 days in 37% of the cases. Also, GA by TCD and Hadlock equation showed highest correlation with GA by LMP followed by FL and BPD and least accurate was AC.
Conclusion: From the study, we can conclude that TCD is the most accurate method for assessment of gestational age in third trimester followed by FL then BPD and the least accurate is the AC. Also, by combining accuracy of TCD (91%) and that of FL (82%) we can be near certain of gestational age in most of our patients even if they are unsure of their dates. Furthermore, TCD and GA by Hadlock equation showed similar accuracy in gestational age assessment. In all methods the accuracy was higher in <35 week than ≥35 week of gestational age. We recommend to conduct this study on larger sample size for further documentation of the proposed assumption.