The Effects of Different Puncture Points on Labor Analgesia Onset: Study Protocol for a Randomized Controlled Trial

Parturients suffer severe pain during the stages of labor, especially the first and second. Epidural anesthesia is an effective method to alleviate labor pain. L2-3, L3-4 and L4-5 spaces have been reported to be the recommendable puncture points owing to the adequate analgesia effect and high safety. However, the speed of pain alleviation via the three points has hardly been determined, which is of great importance to parturients. Thus, the aim of this study is to compare the onset time of parturients' painless uterine contraction after epidural labor analgesia through different puncture points.

It is a prospective, randomized, controlled, and subject- and assessor-blinded study. Totally, 150 subjects scheduled for vaginal delivery are going to be randomly assigned into the L2-3 and L3-4 group. Puncture point in L2-3 group is lumbar 2-3 space, while in L3-4 group it is lumbar 3-4 space. Analgesia initiation and maintenance are the same between the two groups. Primary outcome will be percentage of painless uterine contraction 15 min after epidural labor analgesia initiation. Secondary outcomes will be the sensory blocking level, motor blocking score, adverse effects of parturients, drug liquid consumption in unit interval, apgar score and degree of satisfaction of the parturients.

This study estimates the onset time of parturients' painless uterine contraction after epidural labor analgesia through L2-3 or L3-4 space. The results may provide a better choice to relieve labor pain as soon as possible.