Investigators want to set up a randomized clinical trial with 2 arms : Ultiva® and lidocaine versus sufentanil and lidocaine (standard protocol), it is a bicentric study. The primary outcome is the interval between the vascular injection of lidocaine and fetal asystole. The secondary outcomes are the success rate of method, the number of puncture of the umbilical cord, the maternal side effects and the quality of fetopathologic analysis.