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What is Most accurate estimation of gestational age on USG is done by? and explain in detail?
Ans. is 'd' i.e., Crown rump length Determination of gestational age and assessment of fetal size* Fetal body measurements reflect the gestational age of the fetus. The following measurements are usually made: -i) Crown-rump length (CRL): - This is the most accurate method. It is to be used in first trimester. It gives very accurate estimation of the gestational age.ii) Femur length (FL): - Used in 2nd & 3rd trimester.iii) Biparietal diameter (BPD): - Used in 2nd & 3rd trimester.iv) Abdominal circumference (AC): - Used in 3rd trimester. It reflects more of fetal size and weight rather than age.v) Head circumference (HC): - Used in 3rd trimester.