Medicine
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This repository contains the published and unpublished research of the Faculty of Medicine by the staff members of the faculty
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Item First-trimester ultrasound determination of chorionicity in twin pregnancy(Wiley, 2011) Dias, T.; Arcangeli, T.; Bhide, A.; Napolitano, R.; Mahsud-Dornan, S.; Thilaganathan, B.OBJECTIVE: To determine the accuracy of ultrasound at 11-14 weeks' gestation in the diagnosis of chorionicity in twin pregnancy. METHODS:This was a retrospective observational study of data obtained between 1999 and 2010. At the first-trimester routine ultrasound scan,chorionicity was assigned according to the number of placental masses and T or λ-signs for a single placental mass. Chorionicity was confirmed by histology or discordant sex at birth. RESULTS: A total of 648 pregnancies were assigned chorionicity by first-trimester ultrasound during the study period. Chorionicity was ascertained in 613 cases, either by histology (n = 340) or discordant sex (n = 273). Chorionicity was correctly assigned by ultrasound at 11-14 weeks in 612 of 613 pregnancies (accuracy 99.8%). Sensitivity and specificity for determining monochorionicity were 100% and 99.8%, respectively.CONCLUSIONS:First-trimester ultrasound can be used to determine chorionicity reliably by noting the number of placental masses and T or λ-signs.Determination of twin chorionicity is important and should be completed in the first trimester.Item Second-trimester assessment of gestational age in twins: validation of singleton biometry charts(Wiley, 2011) Dias, T.; Arcangeli, T.; Bhide, A.; Mahsud-Dornan, S.; Papageorghiou, A.; Thilaganathan, B.OBJECTIVE: To determine the accuracy of dating twin pregnancies, of between 16 and 26 weeks' gestation, using singleton head circumference (HC) formulae. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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