Approach for estimating fetal body weight using two-dimensional ultrasound.
OBJECTIVE
Estimation of fetal weight is essential in daily obstetric clinical practice. Most formulas for the estimation involve head measurement. However, predicting fetal weight by head measurement is virtually impossible when the fetal head is positioned low in the pelvic cavity. A convenient method for estimating fetal body weight without head measurement is therefore required.


METHODS
Women who delivered between August 2001 and June 2002 in our center were the subjects of the present study. All infants were delivered within 48 h of an ultrasound examination. Only thigh measurements were made in an attempt to obtain an estimation formula by conventional two-dimensional ultrasonography in 83 patients. As a parameter, femur length (FL) and the largest cross-sectional area at right angles to the long axis of the thigh were used. The derived formula was compared with an established equation in 58 parturients.


RESULTS
The FL value multiplied by the square root of the cross-sectional area of the thigh showed a significant correlation with the actual birth weight. A formula with only two parameters (FL and cross-sectional area of the thigh) was found by linear regression.


CONCLUSIONS
The formula derived using only thigh measurements was found to be convenient among all the established formulas for estimated fetal body weight, and no head measurement was necessary.
Isobe
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Department of Obstetrics and Gynecology, Kinann Hospital, Mie, Japan.
D000465:Algorithms; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000196:embryology; D020567:Fetal Weight / Q000502:physiology*; D006801:Humans; D010384:Pelvic Bones / Q000000981:diagnostic imaging / Q000196:embryology; D010388:Pelvis / Q000000981:diagnostic imaging / Q000196:embryology; D011247:Pregnancy; D013848:Thigh / Q000000981:diagnostic imaging / Q000196:embryology; D016216:Ultrasonography, Prenatal