[Pathophysiology, diagnosis and management of occiput posterior presentation during labor]

Persistant occiput posterior (OP) positions are the commonest malpresentations of the fetal head during labor and their diagnosis remains challenging. They are associated to prolonged second stage of labor, prolonged expulsive efforts, labor augmentation, cesarean sections and instrumental deliveries. On the maternal side, severe perineal tears, post-partum hemorrhage or chorioamnionitis are more frequent. Currently, prevention of persistent OP positions is based on the maintain of precise maternal positions. Several positions have been evaluated but only lateral position on the same side of the fetal spine has proved its effectiveness. Fetal head rotation can also be achieved with extraction instruments though none has ever been evaluated by a randomized controlled trial. Obstetrical forceps seem more efficient than vacuum but are associated with severe perineal tears. Evaluation of rotation with Thierry's spatulas is scarce. Last, manual rotation is of routine use in many wards. This management is associated with a twofold reduction of operative delivery rate and rare adverse outcomes but has never been evaluated through randomized control trial.