The purpose of this study is to investigate the analgesic effect of low-dose intravenous ketamine in pregnant mothers undergoing cesarean section under Bupivacaine spinal anesthesia.

• No premedication will be given, and patients will be monitored by electrocardiogram, non-invasive arterial blood pressure, and pulse oximetry when they entered the operating room.
• 18 gauge IV cannula will be inserted and all patients will be preloaded with 10 ml/kg of lactate ringer over 20 min period.
• All participants will have spinal anesthesia using bupivacaine. The dose of the drug, as well as the method of injection will be identical for all individuals; 10 mg (2 cc 0.5%), in the L4-L5 space using needle 25 G, midline, with the patient in a sitting position.
• After administering bupivacaine, and prior to surgery the height of the sensory block will be assessed bilaterally (complete loss of sensation to ice) in a ascending fashion starting from T12 dermatome.
• Once adequate anesthesia to at least T6 dermatome will be achieved, the operation will be allowed to begin. When systolic blood pressure decrease to < 90 mmHg, or 30% of the pre-anesthetic blood pressure, it will be corrected by administering 5 mg ephedrine.
• Patients will be asked to report any intraoperative pain using visual pain score(VPS)of 0(no pain) 10(worst pain).

Inclusion Criteria:

• Eligible women ASA class 1 and 2, are at term (≥37 week gestation), Scheduled for elective cesarean section whose anesthetic plan is for spinal anesthesia with Bupivacaine and intravenous pethidine and paracetamol for post operative analgesia.

Exclusion Criteria:

• • Body mass index ≥40 kg/m2,

  • Known allergy to any of the study medications,
  • Contraindication to the spinal anesthesia,
  • History of substance abuse,
  • History of hallucinations,
  • Chronic opioid therapy,
  • Chronic pain.