What is the initial workup for a patient presenting with low back pain?

Workup for Low Back Pain

For acute low back pain without red flags, do not order imaging—conduct a focused history and physical examination to identify red flags, then initiate conservative management with activity modification and simple analgesics. 1

Initial Clinical Assessment

History and Physical Examination

Screen immediately for red flags that require urgent imaging or specialist referral: 1

• Cauda equina syndrome: urinary retention, fecal incontinence, bilateral leg weakness, or saddle anesthesia (90% sensitivity) 2
• Malignancy indicators: history of cancer, unexplained weight loss, age >50 years, failure to improve after 1 month 1
• Infection: fever, recent bacterial infection, IV drug use, immunosuppression 1
• Fracture risk: significant trauma, osteoporosis, chronic steroid use, age >65 years, midline tenderness 1, 2
• Severe neurologic deficits: progressive weakness, ascending sensory loss, or spinal cord compression signs 2

Perform neurological examination including: 1

• Straight leg raise test for radiculopathy (91% sensitivity for herniated disc) 3
• Motor strength testing in lower extremities
• Sensory examination for dermatomal patterns
• Reflexes (patellar and Achilles)

Assess psychosocial risk factors using the STarT Back tool at 2 weeks: 1

• Depression, anxiety, catastrophizing
• Fear-avoidance beliefs
• Job dissatisfaction, disputed compensation claims
• Passive coping strategies

These factors strongly predict progression to chronic disabling pain and guide treatment intensity. 1

Diagnostic Imaging Strategy

When NOT to Image

Do not order imaging for acute uncomplicated low back pain (<4 weeks) without red flags, even with midline tenderness. 4, 1 Routine imaging provides no clinical benefit, exposes patients to unnecessary radiation, and disc abnormalities are common in asymptomatic patients (29-43% prevalence depending on age). 4

When to Image

Order immediate MRI or CT if: 1, 2

• Any red flags are present (cauda equina, severe neurologic deficits, suspected malignancy/infection)
• Progressive neurologic deficits develop
• MRI is superior because it avoids radiation and better visualizes soft tissue, vertebral marrow, and spinal canal 1

Consider plain radiography only if: 1

• Risk factors for vertebral compression fracture exist (osteoporosis, steroid use, age >65)
• Symptoms persist beyond 4-6 weeks despite conservative management
• Patient has not improved with conservative therapy

Order MRI for radiculopathy if: 3

• 4-6 weeks of conservative management with little improvement
• Severe symptoms or significant neurological findings at initial presentation
• Patient is a potential candidate for surgery or epidural steroid injection

Laboratory Testing

No routine laboratory tests are indicated for uncomplicated low back pain. 1 Consider labs only when red flags suggest specific conditions:

• ESR/CRP if infection or inflammatory condition suspected
• Complete blood count if malignancy suspected
• Bone density testing if fracture risk factors present

Risk Stratification and Management Algorithm

Low-Risk Patients (STarT Back tool)

Minimal psychosocial barriers to recovery: 1

• Provide self-care education and reassurance
• Advise to stay active and avoid bed rest
• Apply superficial heat using heating pads
• Acetaminophen (up to 4g daily) for mild-moderate pain
• NSAIDs if acetaminophen insufficient

Medium-Risk Patients

Refer to physiotherapy at 2 weeks and develop patient-centered management plan: 1

• Consider nonpharmacologic treatments: massage, acupuncture, or spinal manipulation
• NSAIDs or skeletal muscle relaxants if pharmacologic treatment desired 1

High-Risk Patients

Refer for comprehensive biopsychosocial assessment by physiotherapy and review no later than 12 weeks: 1

• Consider psychological interventions if psychosocial factors prominent
• Intensive interdisciplinary rehabilitation for subacute pain (4-8 weeks) 1

Follow-Up and Reassessment

Reevaluate at 1 month if symptoms persist without improvement. 1 Consider earlier reassessment for:

• Patients over 65 years
• Signs of radiculopathy or spinal stenosis
• Worsening symptoms

If symptoms persist beyond 4-6 weeks without improvement: 1

• Consider plain radiography if not previously performed
• Refer for physical therapy or intensive rehabilitation
• Reassess for red flags that may have developed

Common Pitfalls to Avoid

Do not order routine imaging for uncomplicated acute low back pain—this exposes patients to unnecessary radiation without clinical benefit and may lead to overtreatment of incidental findings. 4, 1

Do not prescribe prolonged bed rest—maintaining activity reduces disability and improves outcomes. 1

Do not rely on opioids for initial management—they have abuse potential and lack superior efficacy compared to NSAIDs. 1

Do not fail to assess psychosocial factors—depression, anxiety, catastrophizing, and fear-avoidance beliefs are strong predictors of chronicity and require early identification and intervention. 1