Role of Fetal Kidney Length in Estimation of Gestational Age.

ABSTRACT

Fetal Kidney Length (FKL) is most accurate single parameter for estimating GA than other biometric indices in late 2nd and 3rd trimester and could be easily incorporated into the models for estimating GA. We evaluated role of FKL in estimation of gestational age (GA) in late 2nd & 3rd trimester. A total of 98 pregnant women with singleton pregnancy underwent serial biometric & FKL measurements ultrasonographically at 24, 28, 32, 36 and 38 weeks of gestation. These measurements were used to date the pregnancies relative to dating by last menstrual period. Linear regression models for estimation of GA were derived from the biometric indices and FKL. New models were constructed by combining different biometric indices and kidney length in various combinations. Comparison of accuracy in prediction of GA was made between individual parameters and these models to obtain best individual parameter and the best model in prediction of gestational age. Left FKL was slightly, but significantly longer than right FKL at each gestational period observed in the study. Standard error of prediction of GA was least for FKL (±8.56 days), closely followed by femur length (±8.9 days) and maximum for abdominal circumference (±11.72 days). The best model in estimating GA included all the five variables (femur length, FKL, biparietal diameter, head and abdominal circumference) with a standard error of ±7.41 days. FKL is the most accurate single parameter for estimating GA than other biometric indices in late 2nd and 3rd trimester and could be easily incorporated into the models for estimating GA.