Sonographic estimation of gestational age using transverse cerebellar diameter among late trimester pregnancies in Kano, Northwest Nigeria

Abstract

Background/Context: Accurate estimation of fetal gestational age (GA) is of paramount importance in the management of all pregnancies, especially for the planning of mode of the delivery and management of high-risk pregnancies. Obstetric ultrasonography is a simple, available, affordable, and noninvasive modality for estimating fetal GA due to its high safety profile. The fetal cerebellum is easily visualized and reliably identified on ultrasound in the posterior cranial fossa after 14 weeks of gestation. Aim: The aim of this study was to evaluate the utility of transverse cerebellar diameter (TCD) in determining GA in second- and third-trimester pregnancies and compare its accuracy with other established sonographically derived fetal biometric parameters. Materials and Methods: A total of 424 pregnant women in their second and third trimesters who were sure of their last menstrual period (LMP) were recruited into the study over a period of 6 months (May to November 2019) at the Radiology Department of AKTH-Kano, Nigeria. The corresponding fetal TCD and other established fetal biometric indices (biparietal diameter [BPD], head circumference [HC], abdominal circumference [AC], and femur length [FL]) were sonographically obtained and correlated. Pearson’s bivariate coefficient was used to establish the correlation between the traditional biometric indices with TCD and GA derived by LMP. Multivariate linear regression analysis was used to assess the accuracy of the studied indices in predicting GA. Results: The range for TCD in second- and third-trimester fetuses was 15.9–57.5 mm. The TCD parameter was more accurate (±1.753 days) than BPD (±2.298 days), HC (±2.337 days), and AC (±4.342 days) and marginally less accurate than FL (±1.165 days) in predicting GA among study subjects (P < 0.001). Conclusion: TCD is a reliable and accurate parameter for GA estimation in late second- and third-trimester pregnancies when compared with established fetal biometric parameters among pregnant women in Kano, Nigeria.