Intrathecal Nalbuphine is a Comparable Safer Alternative to Fentanyl for Intraoperative Pain Management During Uterine Exteriorization

"All patients will be put in the sitting position and lean forward. After sterilization, Dural puncture will be performed at L4-L5 interspace or L3-L4 with a 25 gauge Quincke spinal needle.~The patients will be divided equally into 3 groups according to the additive (fentanyl, nalbuphine or placebo), and all patients will receive the local anesthetic dose of 0.5% heavy bupivacaine according to weight and height"