A Study Of Sonographic Evaluation Of Fetal Femur Length For Estimation Of Gestational Age

ABSTRACT

Introduction: Accurate estimation of Gestational age is of great value in proper obstetric care and interventionduring pregnancy. Ultrasound has evolved as a reliable method for accurate measurement of gestational age bymeasuring various fetal biometric features like Crown Rump Length (CRL), Biparietal Diameter (BPD), Femurlength (FL), Abdominal Circumference (AC), Head Circumference (HC), Trans Cerebellar Diameter (TCD) etc. Femurbeing the longest bone in fetus, least movable and easily imagable from second trimester to delivery, can bemeasured for estimation of gestational age. The present study was performed to evaluate femur length in secondand third trimester by ultrasonography, assess gestational age from measurement of Femur Length (FL) anddetermine the accuracy of gestational age assessed by ultrasonography with gestational age assessed by LMPmethod in local population of Gujarat.Materials and Methods: Cross sectional study of total of 200 pregnant women, 100 second trimester and 100third trimester, between 13 and 40 weeks of gestational age attending the department of radiology at P.D.U.Medical college, Rajkot for a fetal ultrasound scan was done. Femur length (FL) was measured; Gestational agewas measured by Hadlock’s method and Loughna P et al’s method; also gestational age was assessed from LMPof the women. The mean values of femur length and predictive accuracy of fetal femur length was analyzed andcompared with other studies.Results: Mean of FL increased progressively from 13-40 weeks of gestation. During both second and third trimesters,Hadlock’s formula and Loughna P’s method were equally accurate to assess the gestational age. But femur lengthwas more accurate in second trimester than in third trimester. There was discrepancy in values of femur lengthas compared to other studies.Conclusion: Like other studies the present study also found the need of fetal charts that were specific for individualpopulation and ethnic group to determine gestational age and EDD to enable the development of better clinicalguidelines for the present population.