Caudal Epidural Steroid Injection

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Pre-Procedure0/2

Perform time-out: verify patient identity, procedure, allergies, and anticoagulation status.

Caudal approach avoids direct needle contact with thecal sac but has higher infection risk due to proximity to the sacral hiatus.

The caudal approach enters the epidural space through the sacral hiatus. It is useful for bilateral lower lumbar and sacral pathology, and in patients with prior lumbar surgery.

Review imaging. Palpate the sacral hiatus to assess anatomy. Note any pilonidal cyst or skin abnormalities.

Avoid the procedure if there is active skin infection near the sacral hiatus or pilonidal disease.

The sacral hiatus is formed by the unfused S5 (and sometimes S4) laminae. The sacral cornua are palpable landmarks flanking the hiatus.

Setup0/2

Position patient prone with pillow under the pelvis to flex the hips and expose the sacral hiatus.

Ensure sterile prep extends widely around the gluteal cleft. This area has higher bacterial colonization.

Hip flexion tilts the pelvis and makes the sacral hiatus more prominent. The hiatus is located approximately at the level of the posterior superior iliac spines.

Obtain lateral fluoroscopic view to visualize the sacral canal and hiatus. Identify the sacral cornua.

Lateral view is the primary working view for caudal epidurals. Confirm the needle trajectory is within the sacral canal.

On lateral fluoroscopy, the sacral canal appears as a lucent line between the dorsal and ventral sacral plates. The sacrococcygeal membrane covers the hiatus.

Procedure0/4

Select a 22-gauge spinal needle or 20-gauge short-bevel needle. Insert through the sacrococcygeal membrane at ~45-degree angle, then flatten to advance into the sacral canal.

Initial steep angle penetrates the membrane, then flatten to avoid penetrating the ventral sacral plate. Advance only 1-2 cm past the membrane.

The sacrococcygeal membrane gives a characteristic 'pop' or 'give' upon puncture. Over-advancement risks anterior dural puncture or penetration into the presacral space.

Confirm needle position on AP view (midline within the sacral canal) and lateral view (within the sacral canal, below the S3 level).

The thecal sac typically ends at S2. Do not advance the needle above the S3 level to avoid dural puncture.

In adults, the thecal sac ends at approximately the S2 level. In some individuals, it may extend to S3. Keeping the needle below S3 provides a safety margin.

Inject 2-3 mL of contrast under live fluoroscopy. Confirm epidural spread pattern ascending the sacral canal.

Absence of epidural spread suggests subcutaneous or presacral placement. If contrast outlines individual nerve roots (myelogram pattern), needle is intrathecal.

Caudal epidural contrast typically shows a linear, smooth pattern ascending the sacral canal, often with a 'railroad track' appearance on AP view.

Inject injectate: 6-10 mL total volume including steroid (triamcinolone 80 mg or dexamethasone 10 mg) and preservative-free normal saline.

Larger volumes are needed for caudal to reach the lower lumbar epidural space. Inject slowly to avoid excessive pressure.

The caudal approach requires larger volumes (6-10 mL) compared to interlaminar (2-3 mL) or transforaminal (1.5-2 mL) because the injectate must traverse the sacral canal to reach the target level.

Post-Procedure0/2

Remove needle and apply sterile bandage. Monitor for 20-30 minutes.

Assess lower extremity strength and sensation. Larger injectate volumes may cause temporary motor block.

Transient lower extremity weakness or numbness is more common after caudal injections due to the larger volumes bathing the sacral nerve roots.

Document procedure details: needle type, fluoroscopic confirmation, contrast pattern, injectate volume and composition.

Document the level of contrast spread (which vertebral levels were covered) to guide future treatment decisions.

If contrast does not reach the target level, the procedure may have reduced efficacy. Documentation helps guide repeat procedure planning.