Fetal Foot Length and Femur/ Foot Length Ratio: Significance in Nepalese Context

Ks Joshi,Nc Shrestha,S Karki,S Tamrakar,Sb Marahatta

doi:10.3126/njr.v1i1.6317

Abstract

Aim: 1. To assess relationship between fetal foot length and gestation age and develop a nomogram. 2. To assess relationship between fetal foot length and femur length. Meterials and Method: Cross sectional study. Fetal foot length was taken from the skin edge overlying calcaneus to the distal end of the longest toe on either plantar or the sagittal view in 860 singleton pregnant women between 15 and 40 weeks’ gestation. Normal case was defined as normal sonographic findings during examination and normal infant examination at birth or both. Final study population constituted 779 healthy fetuses. The relationship between gestational age to foot length was analyzed by simple linear regression. Correlation of fetal foot length with gestational age and femur length were also obtained. Results: A nomogram for fetal foot length was obtained. There is linear relationship between foot length and gestational age [foot length (mm)=2.494xGestational age (weeks)-15.46] with significant correlation (r=0.970 and p=0.000) and between foot length and femur length [foot length(mm)=1.049xfemur length (mm)+0.648] with significant correlation (r=0.980 and P=0.000). Femur length/ Foot Length ratio was 0.9 and 1.0 in most of the cases. Conclusion: Nomogram was obtained for fetal foot length at various gestational ages in our population. There is linear relationship and good correlation between foot length and gestational age and foot length and femur length. Fetal foot length can be used as an alternative fetal parameter to assess gestational age. Femur length/ Foot Length ratio is fairly constant throughout gestation. DOI: http://dx.doi.org/10.3126/njr.v1i1.6317 Nepalese Journal of Radiology Vol.1(1): 15-22

Highlights

NJR I VOL 1 I No 1 I ISSUE 1 I JULY-DEC, 2011 Page[15]Joshi et al Fetal Foot Length and Femur/Foot Length Ratio: Significance in Nepalese Context during sonogram and which do not yield any additional information
Ultrasonographic measurements were made by a real-time system with a 3.5-MHz curvilinear transducer (ACUSON X150, Mountain View, CA 94043 USA)
If there is discrepancy of > 14days; GA by measurement was considered final GA. In addition to these measurements, detailed evaluation of fetus was done from head to Simple linear regression analysis shows linear relationship between foot length and gestational age [foot length = 2.494xGestational age-15.46] with high degree of correlation (r=0.970 and P=0.000) (Fig4)

Summary

Introduction

NJR I VOL 1 I No 1 I ISSUE 1 I JULY-DEC, 2011 Page[15]Joshi et al Fetal Foot Length and Femur/Foot Length Ratio: Significance in Nepalese Context during sonogram and which do not yield any additional information. There are situations where these parameters cannot be used, for example, hydrocephalus, anencephaly, short limb dysplasia and in third trimester pregnancy when the head is already engaged. In these situations, we have to use other parameters for the estimation of gestational age. Mercer et al[10] in a study of two hundred twenty-three postpartum and 224 ultrasonograhic measurements between 11 and 43 weeks’ gestation concluded that fetal foot length is a reliable parameter for use in assessment of gestational age. The study by Platt et al[11] suggest that the measurement of fetal foot length with ultrasound gives a reliable assessment of anatomical fetal or neonatal foot length and is highly correlated to the menstrual age of the fetus. Mhaskar et al[12] performed one hundred and five ultrasonographic measurement of fetal foot length between 13 and 42 weeks gestation and found that ultrasonographic measurement of foot length is a reliable indicator of gestational age

Methods

Results

Discussion

Conclusion