Estimation of Fetal Gestational Age Using Transverse Cerebellar Diameter via Ultrasound in Pregnancies Complicated by Intrauterine Growth Restriction

Background: Accurate estimation of gestational age is critical in the management of pregnancies complicated by Intrauterine Growth Restriction (IUGR), particularly when the last menstrual period is unknown and no early dating scan is available. In such scenarios, the transverse cerebellar diameter (TCD) measured via ultrasound may offer a reliable alternative for assessing fetal age. Objective: To determine the correlation between gestational age estimated by transverse cerebellar diameter on ultrasound and gestational age determined by dating ultrasound in pregnancies affected by intrauterine growth restriction. Methodology: This descriptive cross-sectional study was conducted at the Radiology Department of a tertiary care Armed Forces Hospital in Karachi, Pakistan, from March 1 to November 30, 2024. A total of 161 pregnant women diagnosed with IUGR were enrolled. Gestational age was recorded based on an earlier dating ultrasound. Each participant underwent fetal biometry and Doppler ultrasound to confirm sonological features of IUGR. TCD measurements were then used to estimate gestational age. Data were documented using structured forms and analyzed using SPSS version 23. Pearson correlation was used to assess the relationship between gestational age derived from TCD and that from the dating scan. Results: The mean gestational age calculated from TCD was 35.53 ± 2.14 weeks, compared to 35.60 ± 2.20 weeks from the dating ultrasound. A strong positive correlation was found between the two methods (r = 0.954, p < 0.001). Conclusion: The transverse cerebellar diameter provides an accurate estimate of gestational age in pregnancies with intrauterine growth restriction, closely matching the age determined by early dating ultrasound. This makes TCD a valuable tool in cases where dating scans are unavailable or unreliable. Keywords: Diagnostic Imaging, Fetal Development, Gestational Age, Intrauterine Growth Restriction, Prenatal, Ultrasonography.