title: [Monochorionic biamniotic twins with a common yolk sac in the first trimester ultrasound scan - is there a higher risk of a congenital defect?].
abstract: METHODS
  Case report.
  
  
  METHODS
  GEST IVF, Centre of Reproductive Medicine, Prague.
  
  
  METHODS
  The case report describes pregnancy after IVF + ET. The first trimester ultrasound scan showed monochorionic biamniotic twins with one common yolk sac (YS) only, which is possible in biamniotic twins, but very rare. Identical congenital defects such as anal, coccygeal atresia, and others, were diagnosed prenatally and postnatally in both twins.
  
  
  CONCLUSIONS
  Yolk sac number in monochorionic twins can play an important role in embryogenesi. Any possible relation with certain congenital defects has not yet been described. It is necessary to describe more cases.
authors.affiliation: Centrum reprodukcni mediciny, Praha. monika.polakova@volny.cz
authors.forename: M
authors.initials: M
authors.lastname: Poláková
authors.forename: L
authors.initials: L
authors.lastname: Zetová
authors.forename: R
authors.initials: R
authors.lastname: Vlk
authors.forename: Vejvalková
authors.initials: V
authors.lastname: S
mesh_terms: D000650:Amnion / Q000000981:diagnostic imaging*; D002823:Chorion / Q000000981:diagnostic imaging*; D000013:Congenital Abnormalities / Q000209:etiology; D005260:Female; D005307:Fertilization in Vitro; D006801:Humans; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D014427:Twins; D016216:Ultrasonography, Prenatal; D015017:Yolk Sac / Q000000981:diagnostic imaging*