Estimation of Gestational Age From Fetal Foot Length Measurement

Abstract

The estimation of G. age is vital part of obstetrical ultrasound examination for managing the pregnancy as well as monitoring the growth of the fetus. FFL measurement is a precise method for the calculation of the G.age of the fetus when other methods do not give accurate measurement. Objectives: The main objective of our review is to assess the role of ultrasonographic measurement of foot of the fetus in the calculation of G. age and secondary objective is to measure the FL to FFL ratio in the normal fetuses.  Methods: We conducted the systemic review with the help of following search engines and websites: Google scholar, NCBI, Medline and Medscape databases, Research gate, Science direct, PubMed, Global Health Library, Web of Science, Cochrane, from 1987-2019. Only those studies were included in this review that reported on the determination of the G. age from the FFL measurements on antenatal ultrasonography and on at least one statistic assessing the accuracy of gestational age estimation. The duplicate, non-English and incomplete studies were excluded. After initial screening of 120 studies only 20 studies were eligible for inclusion. All data extracted from them was analyzed using SPSS version 24. Results: After fulfilling eligibility criteria, we were left with 20 studies between years 1987 to 2019. Majority of the studies were conducted in Asia (60%) with study population greater than 50 participants (95%).All of our studies measured FFL for estimation of GA in singleton (80%) and normal (90%) pregnancies. Studies varied in their use of GA reference method, (5%) studies used LMP alone, (10%) studies relied on EDS, (10%) studies used either EDS or LMP as a comparison method, (45%) studies used both EDS and LMP and (30%) studies did not report their reference method. Ten studies reported R with mean value of 0.90002 and SD of 0.073997, 13 studies reported R² with mean value of 0.85192 and SD of 0.156988. Six studies (38%) measured FL to FFL ratio with mean value of 0.96.Fifteen studies reported regression coefficient with mean value of 1.39057 and SD of 1.15890. Conclusions: After reviewing literature of 20 studies it was concluded that FFL is a precise method for the calculation of GA of the fetus. FFL is equally reliable when used with other ultrasonographic parameters as well as when used alone. FFL is also reliable for predicting the estimated FW in the last trimester of pregnancy. FL/FFL is useful in the detection of fetal skeletal dysplasia.