title: Abnormal sonographic appearances of the yolk sac: which can be associated with adverse perinatal outcome?
abstract: OBJECTIVE
  The present study aimed to determine whether yolk sacs with abnormal sonographic appearance are associated with adverse perinatal outcomes in both early and late gestation.
  
  
  METHODS
  A total of 305 viable singleton pregnancies with gestational age of 6 to 9 weeks were prospectively evaluated with respect to perinatal outcomes and sonographic characteristics of the yolk sacs.
  
  
  RESULTS
  An abnormal yolk sac was found in 66 pregnancies. In pregnancies with enlarged yolk sacs a miscarriage occurred in 37.5% of cases (3/8). The pregnancies with a yolk sac diameter >/= 5 mm had a significantly higher risk of miscarriage (p = 0.005). The risk of miscarriage was statistically similar between the pregnancies with regular and those with irregular yolk sacs (p = 0.73). Miscarriage occurred in 3.8% of pregnancies with irregular yolk sacs (2/52) and none of pregnancies with echogenic yolk sacs (0/6). Adverse perinatal outcomes were not associated with either irregular or echogenic yolk sacs.
  
  
  CONCLUSIONS
  An enlarged yolk sac visualized before the 7th week of gestation is strongly associated with a significantly increased risk for spontaneous miscarriage. The presence of an echogenic or irregular yolk sac appears to be unrelated to adverse perinatal outcome.
authors.affiliation: Ankara Atatürk Education and Research Hospital, Department of Radiology, Ankara, Turkey, E-mail: drsinantan@gmail.com.
authors.forename: Sinan
authors.initials: S
authors.lastname: Tan
authors.affiliation: Ankara Atatürk Education and Research Hospital, Department of Radiology, Ankara, Turkey.
authors.forename: Nuray
authors.initials: N
authors.lastname: Gülden Tangal
authors.affiliation: Afyon Kocatepe University Medical Faculty Hospital, Department of Obstetrics and Gynecology, Ankara, Turkey.
authors.forename: Mine
authors.initials: M
authors.lastname: Kanat-Pektas
authors.affiliation: Ankara Atatürk Education and Research Hospital, Department of Radiology, Ankara, Turkey.
authors.forename: Ayşenur
authors.initials: A
authors.lastname: Sirin Özcan
authors.affiliation: Ankara Atatürk Education and Research Hospital, Department of Obstetrics and Gynecology, Ankara, Turkey.
authors.forename: Hüseyin
authors.initials: H
authors.lastname: Levent Keskin
authors.affiliation: Ankara Atatürk Education and Research Hospital, Department of Radiology, Ankara, Turkey.
authors.forename: Gökçe
authors.initials: G
authors.lastname: Akgündüz
authors.affiliation: Etlik Ihtisas Research and Education Hospital, Department of Radiology4, Ankara, Turkey.
authors.forename: Mehmet
authors.initials: M
authors.lastname: Akif Teber
authors.affiliation: Ankara Atatürk Education and Research Hospital, Department of Radiology, Ankara, Turkey.
authors.forename: Halil
authors.initials: H
authors.lastname: Arslan
mesh_terms: D000022:Abortion, Spontaneous / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D005260:Female; D006801:Humans; D015994:Incidence; D011247:Pregnancy; D011256:Pregnancy Outcome / Q000453:epidemiology*; D015203:Reproducibility of Results; D012307:Risk Factors; D012680:Sensitivity and Specificity; D015996:Survival Rate; D014421:Turkey / Q000453:epidemiology; D016216:Ultrasonography, Prenatal / Q000706:statistics & numerical data*; D015017:Yolk Sac / Q000002:abnormalities / Q000000981:diagnostic imaging* / Q000196:embryology*