Accuracy Of fetal kidney length Measurment By Ultrasonography as a parameter for estimating gestational age versus other biometric parameters in the third trimester

Abstract

Background & Aim: Determination of gestational age by ultrasound is not accurate after 34 weeks of gestation,and it has standard deviation ±2 weeks.so should use new ultrasound parameter.although,there is other ultrasound parameters which considered unaccurate in the third trimester of pregnancy.

Materials & Methods: A prospective cross-sectional study was carried out in the Obstetrics and Gynecology University Hospital in Damascus, between august 2018 and February 2021.The study involved 400 pregnant women with singleton pregnancies having no complications between 28 and 41 weeks of gestation. Biparietal diameter, femur length, abdominal circumference, head circumference and kidney length were measured by ultrasound.The study was divided into three subgroups. the first  subgroup: 28-32 weeks, the second subgroup: 33-37 weeks and the third subgroup: 38-41 weeks. the statistics relationship and correlation coefficient were studied between each of these parameters with gestational age which derived from last menstrual period in the three subgroups.

Results: There is significant statistical correlation (P=0.001) and strong (R=0.873) between fetal kidney length and gestational age which derived from last menstrual period in the third trimester. accuracy of fetal kidney length as a parameter increases with progresses gestational age comparision with other ultrasound parameters which its accuracy decrease with progresses gestational age especially in the second subgroup between 33-37 weeks (R=0.825) and the third subgroup between  38-41 weeks (R=0.897)

Conclusions: The study is recommended using the fetal kidney length as an independent parameter in estimating gestational age after 33 gestational week.