Assessment of Gestational Age; Comparison between Transcerebellar Diameter versus Femur Length on Ultrasound in Third Trimester of Pregnancy

.. Objective: To compare correct assessment of gestational age between Transcerebeller diameter versus femur length in third trimester (28-40) using first day of last menstrual period for actual period of gestation. Study Design: Cross-sectional descriptive study. Place and Duration of Study: Department of Obstetrics and Gynecology, Bahawal Victoria Hospital, Bahawalpur from Jun 2012 to Dec 2012. Methodology: This study was performed on 327 patients in third trimester of pregnancy from 28-40 weeks fulfilling the inclusion criteria. Ultrasound measurements of transcerebellar diameter (TCD) and femur (FL) were made with commercially available real time ultrasound equipment Toshiba Nemio-10 model 2009, Transducer frequency 50/60 Hz. Collected data was analyzed by SPSS version 10. Results: Out of 327 patients, TCD was found to give correct assessment corresponding to the gestational age by LMP in 262 (80.1%) patients, while in 232 (70.9%) patients FL was found to give correct assessment corresponding to the gestational age by LMP. Conclusions: Transcerebellar diameter is more reliable method of gestational age determination in third trimester of pregnancy than femur length. TCD can be used as a tool to assist in the assessment of gestational age in third trimester.