Skip to main content
WardSpace
Presentations

Approach to back pain with red flags

The same eight steps, every presentation: threats first, then the history and exam that discriminate, one honest sentence, a mechanism-grouped differential, and the tests read in order.

  1. Immediate threats

    • Cauda equina: saddle anesthesia, retention with overflow, bilateral leg symptoms: MRI within hours, not days
    • Fever with focal spinal tenderness (especially with IV drug use or recent bacteremia): epidural abscess
    • Known or suspected cancer with new back pain: cord compression, dexamethasone on suspicion
    • Tearing pain radiating to the back with pulse or pressure asymmetry: aortic dissection wearing a back-pain costume

  2. History that discriminates

    • Age over 50, cancer history, weight loss, night pain unrelieved by rest: the malignancy cluster
    • Fever, immunosuppression, IV drug use, recent instrumentation: the infection cluster
    • Bladder and bowel function asked directly; numbness where they wipe
    • Trauma proportionate to age and bone (a fall from standing is trauma in osteoporosis)
    • Morning stiffness over an hour in the young: the inflammatory pattern

  3. Examination

    • Focal bony tenderness to percussion (infection, fracture) versus paraspinal muscle tenderness
    • Straight leg raise; power, reflexes, and sensation by root
    • Perianal sensation and anal tone, with a post-void bladder scan, whenever cauda equina is even on the table
    • Pulses and pressures both arms for the dissection story

  4. Problem representation

    A 68-year-old with prostate cancer and two weeks of thoracic night pain, now with band-like numbness and brisk knee reflexes (points at cord compression) versus a 28-year-old with acute lumbar pain after lifting, normal neurology, no flags (points at mechanical strain).

  5. Differential, by mechanism

    Compressive

    • Cord compression
    • Cauda equina
    • Disc herniation with radiculopathy

    Destructive

    • Metastasis and myeloma
    • Vertebral osteomyelitis and discitis
    • Epidural abscess
    • Osteoporotic fracture

    Inflammatory

    • Axial spondyloarthritis

    Referred / visceral

    • Aortic pathology
    • Pancreatitis
    • Pyelonephritis and renal colic

  6. Investigations

    • MRI is the answer to a spinal red flag; plain films answer almost nothing except fracture
    • CBC, CRP or ESR, calcium; myeloma screen and PSA where the destructive cluster is in play
    • Blood cultures before antibiotics when infection is credible
    • Bladder scan: a painless full bladder is the retention that patients do not report

  7. Interpretation

    • Mechanical pain without flags needs no imaging in the first weeks; imaging it anyway breeds incidentalomas and fear
    • Inflammatory markers near-normal make discitis unlikely but do not exclude it with a matching story
    • Neurology that progresses between two exams outranks any single finding

  8. Next steps

    • Suspicion of cord compression: dexamethasone immediately, urgent MRI, oncology and surgical referral in parallel
    • Mechanical pain: stay active, adequate analgesia, no bed rest, review with written flag advice
    • The inflammatory pattern goes to rheumatology with an MRI of sacroiliac joints, not to repeat lumbar films

Connected

ApproachThe joint version of red flagsFluidThe hot joint tapTopicBuilding the differential

Take it further

Copy this page as study notes, then paste them into QSpace for practice questions or AnkiGen for flashcards.

Open QSpace Open AnkiGen