What imaging modalities are indicated for acute low back pain in the Emergency Department (ED)?

From the Guidelines

Imaging is generally not recommended for acute low back pain in the emergency department unless specific red flags are present, as stated in the most recent guideline from the American College of Radiology 1. These red flags include signs of cauda equina syndrome (such as saddle anesthesia, bowel/bladder dysfunction), suspected infection (fever, immunosuppression, IV drug use), history of cancer, significant trauma, or neurological deficits. For most patients with acute low back pain, conservative management should be initiated first, including:

• NSAIDs like ibuprofen 400-600mg every 6-8 hours or naproxen 500mg twice daily for pain relief
• Encouragement to maintain normal activities as tolerated
• Muscle relaxants such as cyclobenzaprine 5-10mg three times daily may be added for severe muscle spasm Imaging should be deferred because most acute low back pain is self-limiting and resolves within 4-6 weeks regardless of imaging findings. Additionally, incidental findings on imaging that are not clinically relevant can lead to unnecessary interventions, increased patient anxiety, and higher healthcare costs. If pain persists beyond 4-6 weeks without improvement despite conservative management, follow-up with primary care and possible imaging at that time may be appropriate, as suggested by the American College of Physicians and the American Pain Society 1. The American College of Radiology also recommends that imaging be considered in patients who have had up to 6 weeks of medical management and physical therapy that resulted in little or no improvement in their back pain, or in those presenting with red flags, raising suspicion for a serious underlying condition 1.

From the Research

Acute Low Back Pain Imaging in ED

• The management of acute non-specific low back pain in the emergency department (ED) is a topic of interest, with studies suggesting that ED physicians may not always follow guidelines 2.
• A systematic review found that the prevalence of serious spinal pathologies in patients presenting to the ED with low back pain is higher than in primary care settings, highlighting the importance of accurate diagnosis and imaging 3.
• Red flags, such as suspicion or history of cancer, intravenous drug use, and other infection sites, can increase the likelihood of a serious condition and may warrant imaging studies 3.
• Current guidelines recommend avoiding imaging studies or invasive treatments for acute non-specific low back pain, unless red flags are present or there is a neuromuscular deficit 4, 2.
• However, a study found that a substantial proportion of ED physicians considered imaging studies, such as MRI, and treatments with questionable benefit, such as oral steroids and muscle relaxants 2.

Diagnostic Studies and Red Flags

• The diagnostic accuracy of red flags, such as suspicion or history of cancer, is reported to be high, but further validation in high-quality prospective studies is needed 3.
• A systematic strategy for history and physical examination can help reduce unnecessary imaging and inform safe and effective pain management recommendations 5.
• Red flags, such as vertebral fractures, spinal cancer, infectious disorders, and pathologies with spinal cord/cauda equina compression, can indicate serious spinal pathologies and may require immediate or urgent treatment 3.

Treatment and Disposition Strategies

• Current guidelines recommend non-pharmacologic treatment, such as counseling, exercise therapy, and physical therapy, as first-line management for acute low back pain 4.
• Pharmacologic interventions, such as non-steroidal anti-inflammatory drugs, may be used as second-line treatment, but evidence is inconclusive for the use of other medications, such as benzodiazepines and opioids 4, 2.
• ED physicians should consider the potential for chronic low back pain and take steps to prevent progression, such as recommending activity and exercise 4, 2.