Precision of Transcerebellar Diameter in Estimation of Gestational Age Compared to Biparietal Diameter in Singleton Pregnancy During Third Trimester

Abstract

Objective: To determine the precision of gestational age measurement in the third trimester of pregnancy by comparing the accuracy of biparietal diameter and transcerebellar diameter in singleton pregnancy taking last menstrual period as gold standard.

Methodology: The present one-time observational study was conducted from March 2022 to February 2023. There were 162 pregnant women enrolled, with a singleton pregnancy, during third trimester, came to the outpatient department of Shahida Islam Teaching Hospital, Lodhran, Pakistan. The biparietal and transcerebellar diameter of the developing fetus were estimated by radiologists and compared it with gestational age obtained by last menstrual period. McNemar test was employed to compare their significance. Intra-class correlation coefficient (ICC) was applied to establish the relationship between gestational age estimated by transcerebellar diameter and biparietal diameter with that estimated by last menstrual period.

Results: In this study we concluded significant positive correlation between the gestational age estimated by TCD and LMP (r=0.87) with p < 0.001, as well as between BPD and LMP (r=0.71) with p < 0.001. Nevertheless, the strength of the correlation between LMP and TCD outweighed the other. TCD accurately determined gestational age in 90.7% of cases, while BPD only achieved 74% of accuracy rate for gestational age assessment in third trimester.

Conclusion: The precision of transcerebellar diameter (TCD) is more than that of biparietal diameter (BPD) in gauging gestational age during the third trimester of pregnancy.