Immediately after these procedures, the marked site was prepped again using alcohol swab, then the principal investigator left and the interventionist entered the intervention section. And the interventionist inserted a prepared 20-gauge spinal needle into the marked site and pointed the needle toward the sacral hiatus under ultrasonography (Xario, Toshiba, Otawara, Japan) guided. When neither tissue resistance nor subcutaneous injection was noticed after injecting saline, 15 ml of 0.5% lidocaine and 10 mg of dexamethasone were injected.