BACKGROUND: Monoamniotic twins with ultrasonographic evidence of umbilical cord entanglement present a management challenge in the antepartum period. CASES: 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. CONCLUSION: 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.
BACKGROUND: Monoamniotic twins with ultrasonographic evidence of umbilical cord entanglement present a management challenge in the antepartum period. CASES: 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. CONCLUSION: 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.