Park et al. reported the results of a randomized study of the use of ultrasound and the use of C-arm in caudal epidural block. However, it is difficult to determine the overall epidural space contrast agent spread with ultrasound alone, and intravascular injection can be avoided with ultrasound. It was said that the evidence for the efficacy of exclusion of intravascular infusion was not as good as that of the C-arm. Therefore, it was suggested that ultrasound in caudal epidural block should be considered only when it is difficult to use the C-arm as an auxiliary means to guide the needle when the sacral hiatus is less than 2 mm and has a complex anatomical structure. The purpose of this study is to determine the difference between intravascular injection and epidural spread according to the type of needle during caudal block under ultrasound guidance.

Inclusion Criteria:

1. A patient who visited the pain clinic complaining of lower back pain due to lumbar disc/stenosis
2. When NRS of back and/or radiating pain is 4 or more
3. Patients over 19 years of age

Exclusion Criteria:

1. Malignancy
2. Systemic infection
3. Bleeding tendency
4. Contrast Allergy
5. Pregnant women
6. If you cannot read or agree to the consent form
7. If you cannot sign the consent form yourself

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