Role of Fetal Thigh Circumference by Ultrasound in Estimation of Birth Weight

Abstract

Accurate estimation of fetal weight is considered the corner stone of fetal growth assessment. In every day obstetric practice, EFW is a key tool for identifying and managing both small fetuses (BW < 2500 g) and large fetuses (BW > 4000 g). A fetus with growth restriction is at increased risk of hypoxia and perinatal death, on the other hand a macrosomic fetus is associated with an increased risk of cesarean section, fetal injury and maternal complications, armed with this information informed decisions about delivery can be taken, thereby minimizing perinatal morbidity and mortality. For the past 2 decades, sonographic estimation of gestational age and fetal weight has relied on a series of formulas derives from biometric measurements of the fetus, including the fetal head, abdomen and femur. These estimates are not highly accurate, with 86.5% of estimates being within 15% of actual birth weight. Formulas incorporating thigh circumference (TC) measurements may be proven most useful in predicting fetal weight when growth abnormalities are present. Fetal growth aberrations are associated with changes in the soft tissue mas