Assessment of Fetal Age by Measuring Bi-Parietal Diameter and Femur Length in the Third Trimester Using Ultrasonography

Abstract

The main objective of this study was to assess the fetal age by measuring bi parietal diameter and femur length using ultrasonography . Imaging was conducted through allowing the subjects to lie supine , and the transducer was put above the symphysis pubic many sections (longitudinal and transverse) of two fetal barometric bi parietal diameter and femur length were taken. The machine used was Aloka (SSD-500) and Zoncare with 3.5 MHz convex probe.

The findings included that there was strong correlation between the fetal age by bi parietal diameter and femur length R² = (0.849), and another strong correlation between fetal age by bi parietal diameter in (weeks) and bi parietal diameter in (millimeter) R²=0.882.

It was also found that there was strong correlation between fetal age in weeks and femur length in (millimeter) R²= 0.980. There was strong correlation of fetal age by bi parietal diameter in (weeks) and expected date of delivery in (weeks) R²=0.853.

The study also found that there was strong correlation between fetal age by femur length in (millimeter ) and expected date of delivery in (weeks). The study concluded that there was no significance difference between bi parietal diameter and femur length , although there was little relation between them , However the femur length was more accurate for fetal age measurement in third trimester of pregnancy.