What is the diagnosis and treatment for a patient of unknown age and gender with acute stomach/side and back pain for 1 day?

Acute Stomach/Side and Back Pain: Diagnostic Approach and Management

Immediate Diagnostic Priority

The combination of stomach/side pain with back pain lasting 1 day requires urgent evaluation to exclude life-threatening abdominal pathology—specifically pancreatitis, nephrolithiasis (kidney stones), or aortic aneurysm—before attributing symptoms to musculoskeletal back pain. 1

Critical Red Flags to Assess Immediately

Evaluate for the following emergent conditions that can present as combined abdominal and back pain:

• Cardiovascular: Abdominal aortic aneurysm (pulsatile abdominal mass, hypotension, syncope) 1
• Renal: Nephrolithiasis/kidney stones (colicky flank pain radiating to groin, hematuria) 1
• Pancreatic: Pancreatitis (epigastric pain radiating to back, nausea, vomiting, history of alcohol use or gallstones) 1
• Infectious: Endocarditis or systemic infection (fever, recent infection, IV drug use) 1
• Neurologic: Cauda equina syndrome (urinary retention [90% sensitivity], fecal incontinence, saddle anesthesia, bilateral leg weakness) 1

Focused History Elements

Obtain specific details about:

• Pain location: Distinguish between true flank/side pain (suggests renal/abdominal pathology) versus paraspinal pain (suggests musculoskeletal) 1, 2
• Pain radiation: Back pain radiating to groin suggests kidney stones; epigastric pain radiating straight through to back suggests pancreatitis 1, 2
• Associated symptoms: Nausea, vomiting, fever, urinary symptoms, or bowel/bladder dysfunction 1, 3
• Risk factors: Age >50 years, history of cancer, unexplained weight loss, fever, IV drug use, recent infection, history of osteoporosis/steroid use 1

Physical Examination Priorities

Perform targeted examination to differentiate abdominal from spinal pathology:

• Abdominal examination: Palpate for tenderness, masses, pulsatile mass, peritoneal signs, costovertebral angle tenderness 4, 2
• Neurologic examination: Test for motor deficits at multiple levels, reflexes (knee, ankle), sensory distribution, straight-leg raise test 1
• Bladder assessment: Check for urinary retention if cauda equina syndrome suspected 1

Diagnostic Algorithm

Step 1: If any red flags present (fever, hemodynamic instability, pulsatile mass, severe abdominal tenderness, urinary retention, progressive neurologic deficits) → immediate emergency department referral for imaging (CT abdomen/pelvis, ultrasound for AAA) and laboratory testing (CBC, lipase, urinalysis, renal function) 3, 2

Step 2: If abdominal pain is prominent or costovertebral angle tenderness present → obtain urinalysis to evaluate for nephrolithiasis and consider renal ultrasound or CT 1, 2

Step 3: If pain is primarily paraspinal without abdominal findings and no red flags → classify as nonspecific acute low back pain and proceed with conservative management 1, 5

Treatment for Nonspecific Acute Low Back Pain (Only After Excluding Abdominal Pathology)

If evaluation excludes serious abdominal or spinal pathology:

• First-line: NSAIDs (ibuprofen 400-600 mg every 6-8 hours or naproxen 500 mg twice daily) at lowest effective dose for shortest period, after assessing cardiovascular and GI risk 5
• Activity: Advise patient to remain active and avoid bed rest, as activity restriction prolongs recovery 5, 6
• Second-line (if severe pain persists after 2-4 days): Add skeletal muscle relaxant for short-term use (≤1-2 weeks), with cyclobenzaprine 5-10 mg three times daily as preferred agent 5

Critical Pitfalls to Avoid

• Do not assume musculoskeletal etiology without excluding abdominal pathology when stomach/side pain is present—abdominal conditions can mimic or coexist with back pain 1, 4
• Do not order spinal imaging initially unless red flags present, as degenerative changes correlate poorly with symptoms 5
• Do not prescribe systemic corticosteroids, as they are ineffective for low back pain with or without sciatica 5, 6
• Do not use muscle relaxants chronically beyond 2 weeks, as no evidence supports longer efficacy 5

Follow-Up and Reassessment

• Reassess in 2-4 days if treated conservatively to ensure symptom improvement 5
• Immediate re-evaluation required if new symptoms develop: fever, progressive neurologic deficits, worsening abdominal pain, urinary retention, or failure to improve 1, 5
• Most acute nonspecific back pain improves within 4-6 weeks with conservative management 7