Caudal Epidural Block: An Updated Review of Anatomy and Techniques

Figure 6

Color Doppler ultrasonography in longitudinal view of sacral hiatus. A predominantly one-color spectrum is observed in the sacral hiatus during caudal epidural injection. The inset shows the position of the ultrasound transducer. BS: base of sacrum; SCL: sacrococcygeal ligament; SH: sacral hiatus.