Low current electrical stimulation test, also called the Tsui test, has been used successfully to confirm the catheter location in the epidural space in various patient populations. The results of this study will show whether or not doing a Tsui test can predict inadequate epidural analgesia early in the course of placing the epidural, so that the appropriate measures could be applied immediately upon gathering unfavorable results.

Despite its very high success rate, the epidural technique remains a rather blind technique, and failures continue to occur. The incidence and reasons for failure are not well understood. The Tsui test is not routinely performed with each epidural catheter insertion, but rather it is used when there is suspicion about the catheter location.

In this study, the Tsui test will be performed twice during the epidural procedure, and bupivacaine consumption will be recorded for the first 2 hours.

Information gained from this study could have great impact in clinical practice, since the incidence of inadequate labor analgesia is still relatively high (10-20%), leading to maternal distress and disappointing labor experience.

Inclusion Criteria:

• Women over 18 years of age requesting an epidural for labor and delivery
• Cervix dilated 0-5 cm and pain VAS>6
• Able to communicate in English
• Informed consent

Exclusion Criteria:

• Refusal to provide written informed consent
• Patients unable to communicate in English
• Contraindication to regional anesthesia
• Allergy or hypersensitivity to lidocaine, bupivacaine or fentanyl
• Sedatives or opioids received prior to insertion of epidural catheter
• Abnormal vertebral anatomy, such as previous spine surgery and scoliosis
• Coexisting neurological disorders
• Patients with implanted electronic devices