Evaluation of the Efficacy of the Addition of Magnesium Sulfate to Morphine on the Occurrence of Acute Urinary Retention Following Epidural Anesthesia for Cesarean Section.

When the patient agrees to enter the protocol, the investigators randomize the patient and proceed to the injection of morphine 2 mg into the epidural catheter + magnesium sulfate 500 mg

When the patient agrees to enter the protocol, the investigators randomize the patient and proceed to Injection of morphine 2 mg into the epidural catheter + isotonic saline. This is the protocol the investigators use in daily practice for parturients who have undergone Caesarean section, in line with the French recommendations of anesthesia societies