Premixed, Sequential and Manually Mixed Administration of Intrathecal Fentanyl and Bupivacaine in Cesarean Section

Inclusion Criteria: * Age from 18 to 40 years. * Height between 150 to175 cm. * Body mass index (BMI) between 18.5 and 30 kg/m2. * American Society of Anesthesiology (ASA) physical status II. * Scheduled for cesarean section under spinal anesthesia. Exclusion Criteria: * Pre-operation hypotension and bradycardia. * Preeclampsia. * Multiple pregnancy and macrosomia. * Complete or partial failed spinal. * Patients with skin infections at the site of injection. * Patients with coagulation disorders. * Patients with spinal deformities. * Patients having regional nerve block other than spinal anesthesia.