Accuracy of transcerebellar diameter in comparison with biparietal diameter, femur length, and fetal kidney length in the sonographic assessment of gestational age in the third trimester of pregnancy

Abstract

Background When gestational age (GA) cannot be calculated by the date of the last menstrual cycle or an early pregnancy ultrasound, the cerebellar diameter acts as an accurate predictor of GA in the fetus and a criterion against which other fetal parameters can be compared. Aim The aim of this work was to evaluate the accuracy of transcerebellar diameter (TCD) in comparison with biparietal diameter (BPD), femur length (FL), and fetal kidney length in the determination of GA in the third trimester of pregnancy. Patients and methods This was a cross-sectional analysis performed at Tanta University Hospital on 200 singleton uncomplicated pregnant women. Fetal biometric measurements were taken using ultrasound, including TCD, BPD, FL, and fetal kidney length. Results The percentages of accurate assessment of GA within 3 days were as follows: of 200 patients, the TCD gave accurate assessment within 3 days in 120 (60%) patients, the BPD gave accurate assessment within 3 days in 90 (45%) patients, the FL gave accurate assessment within 3 days in 100 (50%) patients, and both right and left kidney lengths gave accurate assessment within 3 days in 100 (50%) patients. Conclusion The TCD is a reliable single parameter for the determination of GA in the third trimester of pregnancy. TCD is a most valuable tool in cases where other established biometric indices are difficult to obtain.