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|Title:||Two corpora lutea seen at 6-13 weeks' gestation infers dizygosity among spontaneous same-sexed dichorionic twins.|
|Epworth Authors:||Tong, Sze|
|Other Authors:||Woo, J.|
Campbell, M. J.
Montgomery, G. W.
Obstetrics and Gynaecology Clinical Institute, Epworth HealthCare, Australia
|Publisher:||Cambridge University Press|
|Citation:||Twin Res Hum Genet. 2009 Apr;12(2):180-2.|
|Abstract:||Current ultrasound techniques can accurately determine the chorionicity of twins, but not zygosity. We previously proposed that the zygosity of spontaneously conceived twins can be determined at early ultrasound, where 2 corpora lutea infers dizygosity, and 1 implies monozygosity. Here we did a case series, comparing zygosity predicted using this method with definitive DNA genotyping of twins after birth. We retrospectively identified 14 ultrasound reports of spontaneous twin pregnancies at 6(+0 days) to 13+6 weeks' gestation, where both ovaries were seen and the number of corpora lutea documented. We visited all twin pairs, obtained buccal smears, and determined zygosity by genotyping 9 independent microsatellite markers. All 8 cases where 2 corpora lutea were seen were dizygotic pregnancies. One further case where 3 corpora lutea were seen was also dizygotic. All 3 sets of monozygotic twins had 1 corpus luteum. There were 2 cases incorrectly assigned, where 1 corpus luteum was seen in dizygotic pregnancies. We conclude if 2 corpora lutea are seen at a first trimester ultrasound of spontaneously conceived dichorionic twins, they appear to be almost certainly dizygotic. However, if 1 corpus luteum is seen in dichorionic twins, zygosity cannot be determined with certainty since it is either monozygotic, or dizygotic where a second corpus luteum has been missed.|
|Journal Title:||Twin Research and Human Genetics|
|Affiliated Organisations:||Southern Health, Women's and Children's Program, Victoria, Australia|
|Type of Clinical Study or Trial:||Case Series and Case Reports|
|Appears in Collections:||Obstetrics & Gynaecology|
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