title: Intertwin discrepancy in middle cerebral artery peak systolic velocity and third-trimester fetal growth restriction in monochorionic-diamniotic twin pregnancy.
abstract: OBJECTIVE
  To assess the role of intertwin discrepancy in middle cerebral artery peak systolic velocity (MCA-PSV) for the prediction of late selective intrauterine growth restriction (sIUGR) at birth and birth weight discrepancy of > 25% (BW-25) in otherwise uncomplicated monochorionic-diamniotic (MCDA) twin pregnancies.
  
  
  METHODS
  This was a cohort study including all MCDA pregnancies followed in a tertiary fetal medicine unit between 2008 and 2013. Exclusion criteria were referral after first trimester, abnormal karyotype, structural anomalies, twin-to-twin transfusion syndrome, twin anemia-polycythemia sequence and sIUGR detected before 28 weeks. MCA-PSV values of both twins measured in the second trimester (18-24 weeks) and early third trimester (26-32 weeks) were converted in multiples of the median (MoM). sIUGR was defined as birth weight < 5(th) centile. The relationship between MCA-PSV discrepancy, sIUGR and BW-25 was assessed by logistic regression analysis. Receiver-operating characteristics (ROC) curves were used to ascertain the predictive value of MCA-PSV discrepancy for such complications.
  
  
  RESULTS
  In total, 136 MCDA twin pregnancies were included in the analysis. Thirty (22.1%) were complicated with sIUGR at birth and 12 (8.8%) were complicated with BW-25. Logistic regression analysis identified MCA-PSV discrepancy as an independent predictor for sIUGR. ROC curves identified third-trimester MCA-PSV discrepancy as the best predictor for both sIUGR (area under ROC curve (AUC), 0.73 (95% CI, 0.62-0.85)) and BW-25 (AUC, 0.79 (95% CI, 0.65-0.93)). The optimal cut-off point for MCA-PSV discrepancy was 0.30 MoM (sensitivity, 70% and specificity, 69% for sIUGR; sensitivity, 83% and specificity, 72% for BW-25).
  
  
  CONCLUSIONS
  In MCDA twin pregnancies, MCA-PSV discrepancy is associated with both sIUGR at birth and BW discordance. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.
authors.affiliation: Department of Obstetrics and Gynecology, University of Brescia, Brescia, Italy.
authors.forename: V
authors.initials: V
authors.lastname: Stagnati
authors.affiliation: Department of Obstetrics and Gynecology, University of Brescia, Brescia, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Pagani
authors.affiliation: Department of Obstetrics and Gynecology, University of Brescia, Brescia, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Fichera
authors.affiliation: Department of Obstetrics and Gynecology, University of Brescia, Brescia, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Prefumo
mesh_terms: D000328:Adult; D001783:Blood Flow Velocity; D016022:Case-Control Studies; D015331:Cohort Studies; D005260:Female; D005317:Fetal Growth Retardation / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging / Q000503:physiopathology*; D011237:Predictive Value of Tests; D011247:Pregnancy; D011263:Pregnancy Trimester, Third; D059285:Pregnancy, Twin; D011673:Pulsatile Flow; D012189:Retrospective Studies; D014427:Twins; D016216:Ultrasonography, Prenatal
keywords: MCA-PSV; intertwin discordance; late IUGR; middle cerebral artery; monochorionic twins; selective IUGR