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Third‐trimester ultrasound dating algorithms derived from pregnancies conceived with artificial reproductive techniques
Author(s) -
Mongelli M.,
Chew S.,
Yuxin N. G.,
Biswas A.
Publication year - 2005
Publication title -
ultrasound in obstetrics and gynecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.202
H-Index - 141
eISSN - 1469-0705
pISSN - 0960-7692
DOI - 10.1002/uog.1939
Subject(s) - medicine , obstetrics , ultrasound , first trimester , algorithm , pregnancy , fetus , radiology , computer science , biology , genetics
Objective To derive an accurate formula for ultrasound estimation of gestational age in late pregnancy. Methods A database of 123 singleton pregnancies conceived by artificial reproductive techniques with third‐trimester ultrasound measurements was studied. Biometry variables included the fetal head circumference (HC) and femur length (FL). The dataset was equally divided into a derivation sample and a target sample. To derive the equations of best fit, regression analysis was used, with true menstrual age as the dependent variable and fetal biometry measurements as independent variables. The formulae were tested on the target set and the menstrual age estimates were compared with the actual menstrual age. Clinical performance was estimated in terms of systematic and random errors, absolute errors and their 95% CI values. Results The menstrual ages at time of scanning ranged from 26 to 41 weeks, with a mean of 33 weeks. The best performing derived formula was a combination of HC and FL. This had a random error of 7.5 days and prediction errors within a 95% confidence limit of −13 to +17 days. With FL only, the random error was 8.2 days, whereas using the HC only yielded a random error of 9.4 days. Conclusions Ultrasound estimation of gestational age in late pregnancy is better than indicated by older publications. It is more accurately estimated by combining the HC with the FL than by using the FL measurements alone. Copyright © 2005 ISUOG. Published by John Wiley & Sons, Ltd.