Accuracy of the Fetal Kidney Length Measurement by Ultrasonography in the Determination of the Gestational Age in Pregnancy

Abstract

Background Definitive calculation of gestational age (GA) forms the basis for rendering standard antenatal care. Depending on the period of pregnancy, various parameters are in use for GA calculation. But none of those fetal biometric indices were observed to be reliable with progression of pregnancy beyond second trimester. Various studies claiming fetal kidney length (FKL) as a reliable index to calculate GA in late trimester have prompted this study to validate and compare this claim with other indices among Indian women in late pregnancy. Materials and Methods This study was done on 100 singleton uncomplicated late pregnant women who knew their last menstrual period definitely. A blinded sonographic process was executed wherein one sonologist measured traditional biometric indices like biparietal diameter, head circumference, abdominal circumference, and femur length and calculated GA. While the other measured only FKL and calculated GA. The results were descriptively analyzed. The correlation of each of the index in accurately calculating GA was done by Pearson’s correlation test. Results FKL was 28.12 mm at 28 weeks and it progressively increased along with GA and it was 40.10 mm at 40 weeks’ gestation. The Pearson’s correlation coefficient of r = 0.926 was observed to be significant compared with other fetal biometric indices measured. Conclusion FKL could be used as a single index to calculate GA in third trimester. Combined with other sonographic fetal indices FKL might increase the accuracy of GA calculation in late pregnancy.