Combined 3-D Fractional Thigh Volume with 2-D Sonographic Biometry for Estimating Fetal Weight

Abstract

Objective : To generate new equation for birth weight estimation in Thai population using fractional thigh volume (Tvol) and conventional two dimensional ultrasound (2D US)

Matetrials and Methods : A prospective, cross-sectional study was conducted. 123 normal fetuses at 37 - 42 week of gestation were examined within 48 hours before delivery. 2D US was performed for conventional fetal biometry and Tvol was collected by three dimensional ultrasound (3D US). The ultrasound was performed by the author who is trained second year obstetric resident. Intra-observer reliability was analyzed using intraclass correlation coefficient (ICC). Stepwise regression analysis was used to generate new equation.

Results : ICC 0.994 for Tvol has showed good intra-observer reliability in this study. Two strong biometry correlated with birth weight are Tvol (r = 0.96) and biparietal diameter (r = 0.44). Birth-weight estimation equation from the study is Birth weight (grams) = 1241.285 + 22.908 Tvol + 43.741 BPD (r² = 0.949).

Conclusion : Tvol is fetal biometry that showed good correlation with fetal birth weight and it could be combined with 2D US biometry to estimate fetal weight.