Peri-medullary anesthesia is the preferred anesthetic technique for Caesarean surgery. Compared with general anesthesia, it reduces maternal and fetal morbidity and mortality, as well as postoperative pain. However, this technique exposes the patient to the adverse effects of peri-medullary morphine, particularly the risk of postoperative urinary retention. Urinary retention during the first 72 hours after Caesarean section affects around 33% of parturients. This is a particularly debilitating event for parturients, exposing them to the risk of further urinary catheterization, increased theoretical risk of urinary tract infection, traumatic urethral injury, hindered accelerated rehabilitation and altered maternal satisfaction. Several studies have demonstrated the benefits of adding magnesium sulfate to epidural anesthesia for Caesarean sections, notably by reducing postoperative pain. Magnesium sulfate may also have a facilitating effect on postoperative micturition, thanks to its sympathicolytic effect. This hypothesis is supported by a retrospective study carried out in our maternity hospital, which showed a 15% reduction in post-Caesarean urinary retention when women were given magnesium sulfate in addition to the drugs traditionally used for epidurals. This little-known property needs to be clarified