What are the next steps for a patient experiencing ongoing pain and swelling in the legs after a spinal injection for back pain?

Urgent Evaluation for Post-Spinal Injection Complications

This patient requires immediate assessment for serious complications of spinal injection, specifically epidural hematoma, epidural abscess, or deep vein thrombosis, as these are life-threatening conditions that can cause permanent neurological damage if not recognized and treated urgently. 1

Immediate Red Flag Assessment

The following symptoms mandate urgent evaluation within hours, not days:

• New-onset severe back or leg pain following spinal injection 1
• Lower limb motor weakness or sensory disturbance 1
• Urinary or fecal incontinence 1
• Urinary retention 1
• Perineal sensory disturbance (saddle anesthesia) 1
• Fever (suggesting epidural abscess) 1
• Progressive leg swelling (suggesting DVT from immobilization or compartment syndrome) 1

Critical Time-Sensitive Actions

Step 1: Neurological Examination (Perform Immediately)

• Motor strength testing in all lower extremity muscle groups bilaterally 1
• Sensory examination including light touch, pinprick, and proprioception in dermatomal distribution 1
• Rectal examination for sphincter tone and perianal sensation 1
• Straight leg raise test to assess for worsening radiculopathy 1

Step 2: Vascular Assessment

• Measure bilateral leg circumferences at multiple levels to quantify asymmetry 2, 3
• Assess for Homan's sign, calf tenderness, warmth, and erythema suggesting DVT 2, 3
• Check distal pulses and capillary refill 3

Step 3: Urgent Imaging Based on Findings

If ANY neurological deficits are present:

• Emergency MRI of the spine with and without contrast to evaluate for epidural hematoma or abscess 1, 4
• This must be obtained within 2-4 hours, as surgical decompression within 24-48 hours of symptom onset significantly improves neurological outcomes 4

If leg swelling without neurological deficits:

• Doppler ultrasound of lower extremities to rule out DVT 2, 3
• Consider MRI if ultrasound is negative but clinical suspicion remains high 2

Thromboprophylaxis Consideration

Patients are at increased risk for DVT following spinal procedures due to:

• Recommended bed rest of 2-24 hours post-procedure 1
• Advised immobilization for 1-3 days after epidural blood patch 1
• Thromboprophylaxis should have been considered during immobilization according to institutional VTE policy 1

Common Pitfall to Avoid

Do not attribute post-injection leg pain and swelling to "normal post-procedure inflammation" without ruling out serious complications. While some discomfort is expected, progressive or severe symptoms warrant immediate investigation 1. The guideline explicitly states patients should seek urgent medical attention for new-onset severe back or leg pain 1.

Disposition Algorithm

If neurological deficits present:

• Emergency neurosurgical consultation 1, 4
• Admit for urgent surgical decompression if epidural hematoma/abscess confirmed 1, 4

If DVT confirmed:

• Initiate anticoagulation per institutional protocol 3
• Admit if hemodynamically unstable or high clot burden 3

If workup negative but symptoms persist:

• Refer to specialist pain management within 2 weeks for severe radicular symptoms 1
• Consider alternative diagnoses including worsening radiculopathy, facet-mediated pain, or sacroiliac joint pathology 5

Follow-Up Requirements

Patients should have been contacted the day following their spinal injection to exclude concerning features 1. If this did not occur and symptoms developed, this represents a systems failure requiring immediate correction 1.