title: What is the definition of pulsatile umbilical venous flow in twin-twin transfusion syndrome?
abstract: OBJECTIVE
  The aim of the study was to derive an objective definition of pulsatile umbilical venous flow (PUVF).
  
  
  METHODS
  Pulsed Doppler waveform analysis of the umbilical vein was performed in stages III and IV twin-twin transfusion syndrome (TTTS) patients. In patients with PUVF, the umbilical vein maximum (Vmax) and the umbilical vein minimum velocity (Vmin) and the resistance index for the umbilical vein (UVRI) = (100 x [Vmax - Vmin]/Vmax) were assessed.
  
  
  RESULTS
  PUVF was noted in 130 of 226 stages III and IV TTTS patients. Digital images were available for analysis in 65 of 130 patients (50%). The minimum UVRI associated with PUVF was 16% for stages III and IV TTTS. There was a trend for increasing UVRI with stage (P = .052). Stage IV patients were more likely to have an UVRI greater than 30% (P = .02).
  
  
  CONCLUSIONS
  PUVF can be defined as an UVRI greater than 15%. A scale definition of PUVF may further facilitate assessment of the degree of fetal hemodynamic compromise.
authors.affiliation: Department of Obstetrics and Gynecology, Division of Maternal-Fetal Medicine, University of South Florida, Tampa, FL, USA.
authors.forename: Zoi
authors.initials: Z
authors.lastname: Russell
authors.forename: Rubén A
authors.initials: RA
authors.lastname: Quintero
authors.forename: Eftichia V
authors.initials: EV
authors.lastname: Kontopoulos
mesh_terms: D000328:Adult; D015331:Cohort Studies; D005260:Female; D005330:Fetofetal Transfusion / Q000000981:diagnostic imaging* / Q000503:physiopathology; D005865:Gestational Age; D006801:Humans; D011247:Pregnancy; D011256:Pregnancy Outcome; D018566:Pregnancy, High-Risk; D011272:Pregnancy, Multiple; D011336:Probability; D011673:Pulsatile Flow / Q000502:physiology*; D012189:Retrospective Studies; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric; D009626:Terminology as Topic; D014430:Twins, Monozygotic; D018617:Ultrasonography, Doppler, Pulsed; D016216:Ultrasonography, Prenatal; D014471:Umbilical Veins / Q000000981:diagnostic imaging*; D014655:Vascular Resistance / Q000502:physiology