The rationale behind the dural puncture epidural (DPE) technique lies in the fact that a dural perforation with a spinal needle purportedly creates a conduit for accelerated translocation of local anesthetics from the epidural to the subarachnoid space. When compared with conventional epidural block, it provides improved sacral block and onset of analgesia.

Despite the benefits associated, the supportive literature remains scarce. No trial has determined if similar results could be obtained with a smaller needle.

In this trial, DPE using 25- and 27-gauge (G) spinal needles are compared. The main outcome will be the time required to obtain a pain score ≤ 1 using a 0-10 numeric rating scale (NRS). The hypothesis is that that both needle sizes will result in similar onset times and therefore designing the current study as an equivalence trial.

Inclusion Criteria:

• healthy pregnant woman
• singleton and vertex presentation
• 37-42 weeks of gestational age
• active labor with cervical dilation < 5cm
• body mass index between 20 and 35 kg/m2
• desired labor epidural analgesia

Exclusion Criteria:

• adults who are unable to give their own consent
• presence of any pregnancy-related disease (e.g., gestational hypertension, preeclampsia, gestational diabetes)
• known fetal anomalies
• increased risk of cesarean delivery (e.g., previous uterine rupture, previous cesarean delivery)
• coagulopathy (assessed by history and physical examination and, if deemed clinically necessary, by blood work up i.e. platelets ≤ 100, International Normalized Ratio ≥ 1.4 or partial prothrombin time ≥ 50)
• renal failure (assessed by history and physical examination and, if deemed clinically necessary, by blood work up i.e. creatinine ≥ 100)
• hepatic failure (assessed by history and physical examination and, if deemed clinically necessary, by blood work up i.e. transaminases ≥ 100)
• allergy to LA
• prior sacral or lumbar spine surgery