This randomized prospective double-blind trial will be conducted on 80 Full-term pregnant females aged 21- 30 years presented for elective cesarean section under spinal anesthesia where they will be randomly allocated into two equal groups:-

• Group F (40 Patients): Patients in this group will receive spinal anesthesia with 10 mg hyperbaric bupivacaine (2 ml) plus 25 ug of fentanyl (0.5 ml).
• Group FN (40 patients): Patients in this group will receive spinal anesthesia with 10 mg hyperbaric bupivacaine (2 ml) plus 25 ug of fentanyl (0.5 ml) plus 20 ug naloxone.

The study aim is to evaluate the effect of adding an ultra-low dose of naloxone (20 ug) to hyperbaric bupivacaine (10 mg0 and fentanyl (25 ug) in spinal anesthesia for C.S.

Primary outcome: The incidence of pruritis Secondary outcome: The onset, the duration, the site, and the severity of pruritis.

This prospective randomized double-blind study will be carried out on 80 female patients who will be presented for elective C.S in the Obstetric department in Tanta university hospitals.

Full-term pregnant female aged 21- 30 years presented for elective cesarean section under spinal anesthesia will be included in the study.

The patients will be randomly allocated into two groups by the aid of computer-generated software of randomization. All the local anesthetic mixtures will be prepared under complete aseptic precautions by an anesthesia resident who will not participate in the study and will be blinded to its groups in to: - Group F (40 Patients): Patients in this group will receive spinal anesthesia with 10 mg hyperbaric bupivacaine (2 ml) plus 25 ug of fentanyl (0.5 ml).

Group FN (40 patients): Patients in this group will receive spinal anesthesia with 10 mg hyperbaric bupivacaine (2 ml) plus 25 ug of fentanyl (0.5 ml) plus 20 ugs naloxone.

Once the patient will be admitted to the operating theatre, all monitors will be applied with introduction of 18-gauge peripheral venous cannula and starting fluid preload in the form of lactated ringer solution 7 ml/kg over 30 minutes. While the patient in a sitting position and under complete aseptic precautions, patients will receive spinal block at lumbar 3-4 or 4-5 intervertebral space with an injection of the pre-prepared local anesthetic mixture according to the group of patient. After giving anesthesia and positioning for surgery with a left lateral tilt of 15 degrees, supplemental oxygen at a rate of 4 liters/minute will be applied.

Inclusion Criteria:

• Full-term pregnant female aged 21- 30 years presented for elective cesarean section under spinal anesthesia.

Exclusion Criteria:

• Patients with pregnancy less than 36 weeks or more than 40 weeks
• Patients with hypertension, pre-eclampsia, or eclampsia.
• Patients with diabetes
• Patients with cardiovascular disease and /or arrhythmia.
• Patients with placenta previa, accreta, percreta.
• Obese patients with BMI >36 Kg/m2
• Patients with height less than 160 Cm
• Multigravida
• Polyhydramnious patients

Full-term pregnant females undergoing elective C.S

The data of primary outcome will be available with the corresponding author till 6 months after approval of the publication of the trial.

6 months after approval of the publication of the trial.

Contact the principle investigator

• The patients will be blinded to their groups.
• An anesthesia resident who will not participate in the study and have no subsequent rule in it will help in the preparation of local anesthetic mixtures under strict aseptic precautions.
• The anesthetist who will perform the spinal anesthesia will be blinded to the local anesthetic mixtures he will inject intrathecally.
• An assistant nurse who will be blinded to the study groups and will have no subsequent rule in it will help in collection of the data of measurments.