What are the possible causes of right‑sided back pain inferior to the ribs along the erector spinae muscles?

Right-Sided Back Pain Below Ribs Along Erector Spinae: Differential Diagnosis

Most cases of right-sided back pain along the erector spinae muscles below the ribs represent nonspecific musculoskeletal pain that resolves with conservative management, but you must systematically exclude serious underlying pathology including renal disease, compression fracture, malignancy, and infection before attributing symptoms to mechanical causes. 1

Primary Diagnostic Categories

The pain you describe falls within the thoracic spine region (lower thoracic vertebrae T9-T12) and can originate from multiple sources:

Musculoskeletal Causes (Most Common)

• Nonspecific mechanical pain accounts for >85% of back pain presentations and involves the erector spinae muscle, fascia, facet joints, or intervertebral discs without identifiable structural pathology 1
• Erector spinae muscle strain or enthesopathy at the iliac crest attachment can cause localized pain, particularly if there has been recent physical activity or repetitive strain 2
• Thoracic facet joint arthropathy may contribute, though morphologic imaging changes do not reliably correlate with pain 1
• Rib-related pain from costovertebral or costotransverse joint dysfunction can present as paraspinal pain in this region 1

Visceral Referred Pain (Critical to Exclude)

• Renal pathology including nephrolithiasis, pyelonephritis, or renal infarction commonly presents as right flank/back pain below the ribs and must be excluded with urinalysis and imaging if clinically suspected 1
• Hepatobiliary disease can refer pain to the right upper back region 1
• Gastrointestinal causes including pancreatitis (though typically left-sided or midline) should be considered 1

Red Flag Conditions Requiring Immediate Evaluation

You must actively screen for these serious conditions:

• Vertebral compression fracture (4% prevalence) - particularly if age >65, history of osteoporosis, or chronic steroid use 1
• Malignancy (0.7% prevalence overall, but 9% if prior cancer history) - suspect with unexplained weight loss, age >50, failure to improve after 1 month, or known cancer history 1
• Spinal infection (0.01% prevalence) - consider with fever, IV drug use, recent infection, or immunosuppression 1, 3
• Inflammatory spondyloarthropathy (0.3-5% prevalence) - suspect in younger patients with morning stiffness, improvement with exercise, and alternating symptoms 1

Clinical Assessment Algorithm

History Elements to Obtain

• Duration and onset: Acute (<4 weeks), subacute (4-12 weeks), or chronic (>12 weeks) 1
• Pain characteristics: Constant vs. intermittent, relationship to activity, positional changes 1
• Associated symptoms: Fever, weight loss, urinary symptoms, neurologic deficits 1
• Red flag screening: Prior cancer, trauma, osteoporosis risk factors, steroid use, IV drug use 1
• Functional impact: Ability to perform daily activities, sleep disturbance 1

Physical Examination Priorities

• Palpation for point tenderness over vertebral bodies (suggests fracture or infection) vs. paraspinal muscles (suggests muscular origin) 1
• Neurologic examination including motor strength, reflexes, and sensory testing to exclude radiculopathy or myelopathy 1
• Costovertebral angle tenderness to assess for renal pathology 1
• Range of motion assessment noting pain reproduction with specific movements 1

Imaging Strategy

Do not order imaging initially for uncomplicated acute thoracic back pain without red flags, as this provides no clinical benefit and may lead to unnecessary interventions. 1, 4

When Imaging Is Appropriate

• After 4-6 weeks of conservative management without improvement 1, 4
• Presence of any red flags at initial presentation 1
• Age >65 with acute onset (consider compression fracture) 1
• Known osteoporosis or chronic steroid use (early imaging warranted) 1

Imaging Modality Selection

• Plain radiographs: Appropriate initial test for suspected compression fracture in high-risk patients 4
• MRI without contrast: Preferred modality for soft tissue evaluation, disc pathology, and infection/malignancy when imaging is indicated 4
• CT without contrast: Alternative if MRI contraindicated, superior for cortical bone detail 1
• Renal ultrasound or CT: If clinical suspicion for renal pathology based on urinalysis or symptoms 1

Initial Management Approach

For uncomplicated mechanical pain without red flags:

• Continue normal activities within pain tolerance - bed rest is contraindicated 4
• NSAIDs or acetaminophen as first-line pharmacologic management 4
• Reassess at 4-6 weeks if symptoms persist, then consider imaging 4

Critical Pitfalls to Avoid

• Ordering routine imaging for acute uncomplicated pain exposes patients to unnecessary radiation and leads to overtreatment of incidental findings 4
• Missing renal pathology by failing to obtain urinalysis when right-sided location suggests possible kidney involvement 1
• Overlooking compression fracture in elderly patients or those on chronic steroids who may have minimal trauma history 1, 4
• Dismissing persistent pain that fails to improve after 4-6 weeks without reconsidering serious pathology including infection or malignancy 3
• Failing to recognize inflammatory causes in younger patients (<45 years) with chronic symptoms and morning stiffness 4