Second-trimester assessment of gestational age in twins: validation of singleton biometry charts
Article first published online: 8 JUL 2010
Copyright © 2010 ISUOG. Published by John Wiley & Sons, Ltd.
Ultrasound in Obstetrics & Gynecology
Volume 37, Issue 1, pages 34–37, January 2011
How to Cite
Dias, T., Arcangeli, T., Bhide, A., Mahsud-Dornan, S., Papageorghiou, A. and Thilaganathan, B. (2011), Second-trimester assessment of gestational age in twins: validation of singleton biometry charts. Ultrasound Obstet Gynecol, 37: 34–37. doi: 10.1002/uog.7740
- Issue published online: 22 DEC 2010
- Article first published online: 8 JUL 2010
- Accepted manuscript online: 8 JUL 2010 12:00AM EST
- Manuscript Accepted: 29 JUN 2010
- head circumference;
- second trimester;
- twin pregnancy
To determine the accuracy of dating twin pregnancies, of between 16 and 26 weeks' gestation, using singleton head circumference (HC) formulae.
This was a retrospective study of 269 singleton and 119 twin non-anomalous pregnancies conceived by in-vitro fertilization (IVF) with a known embryo transfer date. Fetal ultrasound biometry data for HC, obtained using different formulae, were compared with expected fetal HC size for gestation calculated from the date of conception. Similar comparisons were undertaken for femur length (FL) and for transverse cerebellar diameter.
The mean differences in HC between observed ultrasound measurements and those expected from the IVF history were small (1–4 mm) and within the measurement error for both singletons and twins for all formulae. All measurements from the larger and the smaller twins straddled those of singletons, regardless of biometry and formula used. Negative skewing of FL measurements in the smaller twin suggests that fetal growth restriction may occur at this gestation and supports the practice of dating using the HC of the larger twin.
Singleton pregnancy HC charts can be used to date reliably twin pregnancies. The data of the study also suggest that the HC of the larger twin is the most reliable measurement for use in dating. Copyright © 2010 ISUOG. Published by John Wiley & Sons, Ltd.