title: Umbilical artery flow velocity waveforms in monoamniotic twins with cord entanglement.
abstract: BACKGROUND
  Monoamniotic twins with ultrasonographic evidence of umbilical cord entanglement present a management challenge in the antepartum period.
  
  
  METHODS
  We report two pregnancies with monoamniotic twins and ultrasonographic evidence of cord entanglement in which longitudinal Doppler flow velocity waveforms of the umbilical and middle cerebral arteries were obtained. A notch in the umbilical artery velocity waveform was noted in one twin member at 33 weeks' gestation and in both twin members of the other pregnancy at 31 weeks' gestation. Worsening of the umbilical artery velocity waveform notch with advancing gestation was noted in one fetus.
  
  
  CONCLUSIONS
  The presence of a notch in the umbilical artery velocity waveform may reflect hemodynamic alterations in the fetal-placental circulation secondary to narrowing of the umbilical vessels involved in cord entanglement. This Doppler finding may be useful in the antepartum management of these pregnancies.
authors.affiliation: Department of Obstetrics and Gynecology, Eastern Virginia Medical School, Norfolk, USA.
authors.forename: A Z
authors.initials: AZ
authors.lastname: Abuhamad
authors.forename: G
authors.initials: G
authors.lastname: Mari
authors.forename: J A
authors.initials: JA
authors.lastname: Copel
authors.forename: C J
authors.initials: CJ
authors.lastname: Cantwell
authors.forename: A T
authors.initials: AT
authors.lastname: Evans
mesh_terms: D000328:Adult; D000650:Amnion; D001783:Blood Flow Velocity; D005260:Female; D006801:Humans; D011247:Pregnancy; D014427:Twins; D016216:Ultrasonography, Prenatal; D014469:Umbilical Arteries / Q000000981:diagnostic imaging* / Q000503:physiopathology; D014470:Umbilical Cord