The failure in indwelling epidural catheter for a parturient might cause an anesthetic difficulty. Furthermore, no one can predict the accuracy of needle placement prior to skin puncture with any of landmark-based technique. This may result in multiple trying attempts at needle puncture, pain and discomforts of patients and poor patient satisfaction. The aim of this study was to explore the difference of epidural space between parturient and non-pregnant women by assessing ultrasound image.

We will enroll 30 non-pregnant female volunteers and 30 parturients(ASA I-III) underwent epidural blocks. A low frequency ultrasound (2-5 MHz) with a curved array transducer is used to obtain spinal sonography for each subject. The paramedian axis was used to obtain optimal ultrasound image for spinal sonography. Outcome was evaluated by the diameter and depth of epidural space at three lumbar interspaces. Paired T-test was carried out to evaluate the statistical significance of epidual diameter and depth.

Inclusion Criteria:

• parturients scheduled to receive lumbar epidurals for elective cesaeran delivery labor analgesia

Exclusion Criteria:

• Pregancy induced hypertension gestational Diabetes patients who refuse

from Kaohsiung Medical University Hospiral ward parturients