title: Outcome of monochorionic twin pregnancies with abnormal umbilical artery Doppler between 16 and 20 weeks of gestation.
abstract: OBJECTIVE
  To study the perinatal outcome among monochorionic diamniotic (MCDA) twin pregnancies with absent or reversed end-diastolic flow of the umbilical artery (UA-AREDF) at 16-20 weeks of gestation.
  
  
  METHODS
  This was a retrospective study of 84 MCDA twin pregnancies, which were followed up since first trimester in a single obstetric unit. Pregnancies with fetal structural anomalies or genetic syndromes, and those with single intrauterine death before 16 weeks were excluded. The study group was divided into four groups based on the finding of UA-AREDF at the routine follow-up scan at 16-20 week, and the presence of complications at the same time of recruitment. The perinatal outcome between these groups was compared.
  
  
  RESULTS
  AREDF was present in 56.7% of the 30 monochorionic (MC) twins with complications at recruitment. The mortality was significantly higher among those with AREDF. Among the 54 uncomplicated cases at recruitment, only 7.41% had AREDF. The presence of isolated AREDF was associated with significantly higher incidence of growth discordance (25.0% vs. 2%). The incidence of perinatal mortality and twin-to-twin transfusion syndrome was almost doubled (25.0% vs. 9% and 25.0% vs. 14%).
  
  
  CONCLUSIONS
  AREDF of the umbilical artery is uncommon in normal MC twin in mid-trimester. Once AREDF is present, the perinatal outcome is much worse. Doppler assessment of the umbilical artery should be considered in all MC twin pregnancies for risk assessment.
authors.affiliation: Fetal Medicine Unit, Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong, China.
authors.forename: Min
authors.initials: M
authors.lastname: Pan
authors.forename: Min
authors.initials: M
authors.lastname: Chen
authors.forename: Tak Yeung
authors.initials: TY
authors.lastname: Leung
authors.forename: Daljit Singh
authors.initials: DS
authors.lastname: Sahota
authors.forename: Yuen Ha
authors.initials: YH
authors.lastname: Ting
authors.forename: Tze Kin
authors.initials: TK
authors.lastname: Lau
mesh_terms: D002823:Chorion / Q000002:abnormalities*; D005260:Female; D006801:Humans; D018743:Perinatal Care; D054238:Perinatal Mortality; D011247:Pregnancy; D011248:Pregnancy Complications / Q000000981:diagnostic imaging*; D059285:Pregnancy, Twin / Q000706:statistics & numerical data*; D012039:Regional Blood Flow; D012189:Retrospective Studies; D014430:Twins, Monozygotic; D018608:Ultrasonography, Doppler; D016216:Ultrasonography, Prenatal; D014469:Umbilical Arteries / Q000000981:diagnostic imaging / Q000502:physiology*