The objective of this study was to compare four different doses of oxytocin to determine its minimal effective dose during elective cesarean section. A prospective, double-blind, randomized study was undertaken in 40 healthy term parturients presenting for elective cesarean section under regional anesthesia. Subjects were assigned to one of four groups. Group I received 5 IU, Group II 10 IU, Group III 15 IU, and Group IV 20 IU of oxytocin after clamping of the umbilical cord. Uterine tone was assessed by palpation on a linear analog scale (LAS) of 0 to 10 (0 = completely atonic, 10 = fully contracted) at 5, 10, 15 and 20 min after the start of oxytocin infusion. Estimated blood loss (EBL) and the difference in pre- and postoperative hematocrit (delta Hct) were also recorded. At alpha = 0.05, the study design had a power of 95% to detect a 25% difference in the LAS between the four groups. There were no differences in the uterine tone in the four groups at any of the four intervals. EBL and delta Hct were similar in all four groups. There appears to be no benefit in terms of degree of uterine contraction and amount of blood loss to administering more than 5 IU of intravenous oxytocin to term parturients undergoing elective cesarean section with a neuraxial block.

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This is a retrospective observational study demonstrating an association between labor pain and cesarean delivery. Our results provide an alternative explanation of why epidural analgesia is associated with cesarean delivery.

Nulliparity, heavier fetal weight, and epidural catheter placement at an early cervical dilation are predictors of breakthrough pain during epidural labor analgesia. The combined spinal/epidural technique may be associated with a decreased incidence of breakthrough pain.