VP51.01: The "M" sign: systolic middle cerebral artery waveform changes before, during and after fetal myelomeningocele repair. Issue Volume 58:Issue S1(2021)Supplement (14th October 2021) - Vonzun, L.; Gonser, M.; Moehrlen, U.; Mazzone, L.; Meuli, M.; Krähenmann, F.; Zimmermann, R.; Ochsenbein‐Koelble, N.