Yoon JS et al. (2005) The feasibility of color Doppler ultrasonography for caudal epidural steroid injection. Pain 118: 210–214

Caudal epidural steroid injection (ESI) is an established treatment for spine-related problems, although reported success rates vary, largely as a result of incorrect placement of the needle. Use of fluoroscopy improves the accuracy of needle placement, but poses a radiation hazard to the patient. A recent study suggests that ultrasound might offer a safer alternative to fluoroscopy in ESI.

In this study of patients with low back pain and sciatica, Yoon and colleagues used color Doppler ultrasonography guidance to position the needle during ESI and to visualize any vascular intake of the medication. Needle position was then verified using injection of a contrast dye and fluoroscopy. Under ultrasound guidance, medication was successfully injected (defined as unidirectional flow on color Doppler) into the caudal space on first placement in 47 out of 53 patients. Of the 6 failures, the needle was successfully reset in 5, giving an overall success rate of 52 out of 53 patients. Correct placement of the needle was confirmed by fluoroscopy in 50 of the 52 successfully injected patients.

The accuracy of steroid injection into the caudal space using ultrasound guidance was comparable with that obtained using fluoroscopic guidance. The authors conclude that ultrasound is preferable to fluoroscopy for needle guidance during ESI as it is more convenient and does not cause a radiation hazard.