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What are red flags? A comprehensive guide for the major signs and symptoms

Red flags should be the first point of assessment in any condition. Regardless if it is neck pain, shoulder painlower back pain or even foot pain. Red flags are important as they can indicate to the health professional of any serious underlying pathology or anything that would need to be sent to the emergency department for immediate investigations. Across each of the joints, there are some specific red flag signs and symptoms we need to be aware of.

These signs and symptoms should never be interpreted as a direct causation or diagnosis of the conditions that may be associated with them. Instead, a cluster of symptoms are what is commonly used in order to diagnose and correctly identify the condition (Sizer Jr et al., 2007). Therefore, when analysing these red flags, contact with your local doctor is usually the recommended course of action. As in these situations, if an allied health practitioner (e.g. physiotherapist, occupational therapist etc.) identifies any red flags, the usual procedure is to refer onto a doctor for immediate review or referral.

From a clinicians point of view, there are several factors that we need to be aware of (Sizer Jr et al., 2007):

  1. Patient history
    • Physical changes (e.g. changes in bowel and bladder function, blood in sputum, bilateral or unilateral radiculopathy pain)
    • Unresponsive to conservative treatment
  2. Report of present fluctuations in signs and symptoms. Presence of serious pathology is indicated by:
    • Pain that is worse during rest vs activity
    • Worsened at night or not relieved in any position
    • Poor response to conservative care including a lack of pain relief with prescribed bed rest
    • Poor success with comparable treatment
  3. Physical examination and laboratory findings
    • E.g. Abnormal reflexes, gait (movement) changes, strength disturbances / differences, changes to sensation (i.e. numbness, tingling)

The Three Category System

A three categorical classification system has been developed and proposed by Sizer Jr et al. (2007). In this paper Medical Screening for Red Flags in the Diagnosis and Management of Musculoskeletal Spine Pain, he outlines this three step categorical system for each part of the spine. Namely, the cervical, thoracic and lumbar.

The classification system that he uses is as follows:

  • Category 1: Factors that require immediate medical attention
  • Category 2: Factors that require subjective questioning and precautionary examination and treatment  procedures
  • Category 3: Factors that require further physical testing and differentiation analysis
Category 1 Category 2 Category 3
Blood in sputum
Loss of consciousness or altered mental status
Neurological deficit not explained by monoradiculopathy
Numbness or paresthesia in the perianal region
Pathological changes in bowel and bladder
Patterns of symptoms not compatible with mechanical pain (on physical examination)
Progressive neurological deficit
Pulsatile abdominal mass
Age >50
Elevated sedimentation rate
Gait deficits
History of a disorder with predilection for infection or hemorrhage
History of a metabolic bone disorder
History of cancer
Impairment precipitated by recent trauma
Long-term corticosteroid use
Long-term worker’s compensation
Nonhealing sores or wounds
Recent history of unexplained weight loss
Writhing pain
Abnormal reflexes
Bilateral or unilateral radiculopathy or paresthesia
Unexplained referral pain
Unexplained significant upper or lower limb weakness
Sizer Jr et al. (2007)

Cervical Region

Category 1 Findings:

These examinations are usually performed as a result of a trip to the emergency department as a result of motor vehicle accident or fall. Major injuries to this area include fracture or dislocation.

  • Canadian C-Spine Rules (CCR)
  • National Emergency X-Radiography Utilisation Group (NEXUS)

These two decision-making criteria can be used as a screening device to rule out the need for radiography of the cervical spine.

Category 2 Findings:

Mechanical conditions of the cervical spine that require special attention in category 2 are upper cervical instability (atlantoaxial laxity) and vertebrobasilar insufficiency (VBI).

Atlantoaxial laxity

Suspicion of ligament laxity in the upper cervical spine may be tested through two specific physiotherapy ligament tests – The Sharp Purser test and TLA laxity test. Further radiographic evaluation must be undertaken to confirm any upper cervical instability.

Vertebrobasilar insufficiency (VBI)

VBI circulation is important as it can lead to transient ischemic attacks and cerebrovascular accidents. However, difficulties arise as the signs and symptoms of VBI overlap with more common diagnosis, especially vertigo. The red flags that are relevant to this diagnosis are:

  • Visual disturbances (diplopia) – Blurry or double vision
  • Auditory phenomena (sudden sensorineural hearing loss) – Hearing loss
  • Facial numbness or paresthesias – Numbness, tingling or pins and needles especially around the lips or tongue
  • Dysphagia – Difficulty swallowing
  • Dysarthria – Difficulty speaking
  • Syncope (drop attacks) – Sudden syncope episodes

Category 3 Findings:

Finally, the cervical spine should be screened for radiculopathies (pinched nerves) and myelopathies (compression of the spinal cord).

Radiculopathy can be screened through inspection for muscle atrophy (wastage / loss of muscle), sensory changes (numbness, tingling, pins and needles), tendon reflex testing and a positive Spurlings test.

Cervical spine myelopathies can include symptoms such as: loss of dexterity (e.g. difficulty writing or handling small objects), nonspecific weakness (e.g. unable to grip) and abnormal sensations. Lower cervical myelopathies can also include weakness and stiffness in the legs, as well as changes to their walking. The most common cause for myelopathies is a traumatic injury or incident, usually from a stabbing / gunshot wounds, motor vehicle accident or falls.

Thoracic Spine

Category 1 Findings:

There are numerous category 1 red flags that can be found within the thoracic region. Primarily because the same signals that arise from the organs often coincides with a selected region of the musculoskeletal system. Essentially what this means is that the pain felt in a muscle, bone or general upper back area can be caused by pathology involving the organs.

A common example of this relates to acute myocardial infarction (i.e. heart attack). Pain can often be felt in the left pectoral region (i.e. around the left nipple of the chest) and the upper arms or sternum. This is often associated with pallor (pale color of skin), sweating and nausea.

Tumours, metastatic disease, metabolic diseases and fractures can also create pain signals around the area. These conditions can often be marked by severe thoracic pain, decreased range of movement of the thoracic region and potential intercostal neuralgia (i.e. stabbing, burning pain between the ribs).

Category 2 Findings:

Of particular concerns are osteoporotic changes to the thoracic vertebrae, which can lead to severe changes of postural deviations, vertebral fractures or spinal cord injury. A red flags can be evaluated to identify the potential likelihood, including:

  • Age over 50
  • Long-term corticosteroid use
  • Presence of menopause

Category 3 Findings:

As discussed previously, category symptoms require further physical testing and differential analysis. Within the category 3 classification for thoracic level related pathology, many of these symptoms must be clustered together to provide any meaningful reasoning. These symptoms include:

  • Referral pain to the front and side of the rib cage
  • Parathesia or dysthesia (e.g. numbness, tingling, pins and needles, abnormal changes to touch and feeling)
  • Sensory loss (e.g. absence of feeling)
  • Bowel and bladder changes
  • Hyper-reflexia (associated with reflex testing)
  • Coordination loss

Lumbar Spine

Lower back pain is extremely common and these red flags are important, as they can indicate more serious diagnosis such as: malignancy, spinal fracture, infection or cauda equina syndrome (Downie et al., 2013).

Category 1 Findings:

The category 1 symptoms as mentioned in Table 1 outline many of the symptoms that are evaluated in lumbar spine pain for red flags, particularly of which include:

  • Numbness or paresthesia in the perianal region
  • Pathological changes in bowel and bladder
  • Patterns of symptoms not compatible with mechanical pain (on physical examination)
  • Progressive neurological deficit

Category 2 Findings:

Similar to the thoracic spine, lumbar vertebrae are also at risk of compression fractures. The risk factors relative to the lumbar spine remain the same as the thoracic region. Infections can also arise in the lumbosacral region, which produce symptoms such as:

  • Fever
  • Malaise
  • Potential bowel and bladder symptoms
  • Severe lower back pain
  • History of drug use
  • Prior spinal implementation or surgery
  • Severe lower back pain radiating into both buttock and thighs

Category 3 Findings:

Lower back pathology can sometimes be associated with altered or changes in sensory, motor and reflexes. These can be tested through physiotherapy sensation tests, muscle tests and reflex testing. Two common tests we also use to assess nerve involvement is the straight leg raise test or slump sitting test.

Other serious pathology

Signs and symptoms unrelated to the spine can also manifest in other serious conditions. These include infections, malignancy (cancer) or a more serious pathology called ankylosing spondylitis.

Chou et al. (2007) briefly outlines some of the symptoms that are associated with a more severe diagnosis:

  • Cancer:
    • History of cancer
    • Unexplained weight loss
    • Failure to improve after 1 month
    • Age >50 years old
  • Infection:
    • Fever
    • Previous drug use
    • Recent infection
  • Ankylosing Spondylitis
    • Younger age
    • Morning stiffness
    • Improvements with exercise
    • Alternating buttock pain
    • Awakening due to back pain during the second part of the night only


As you can probably tell, there is a lot of overlap between symptoms for each region as well as other pathologies. Many of the findings in category 3 also present in category 1. Which is why a cluster of testing is required in order to rule in or out any certain pathologies.

The world of diagnosis through the use of signs and symptoms is still evolving, and there is certainty more ongoing research require to create established clinical guidelines for clinicians (Chou et al., 2007; Downie et al., 2013; Verhagen et al., 2016).

So if you do have any of these red flags, the important thing to remember is to take a deep breath, relax and go seek a professional opinion from a healthcare professional. Ideally in these situations, a doctor would be first point of call, as they can directly refer or treat many underlying pathologies not related to the musculoskeletal system.


  • Chou, R., Qaseem, A., Snow, V., Casey, D., Cross, J. T., Jr, Shekelle, P., Owens, D. K., Clinical Efficacy Assessment Subcommittee of the American College of Physicians, American College of Physicians, & American Pain Society Low Back Pain Guidelines Panel (2007). Diagnosis and treatment of low back pain: a joint clinical practice guideline from the American College of Physicians and the American Pain Society. Annals of internal medicine, 147(7), 478–491.
  • Downie, A., Williams, C. M., Henschke, N., Hancock, M. J., Ostelo, R. W., de Vet, H. C., Macaskill, P., Irwig, L., van Tulder, M. W., Koes, B. W., & Maher, C. G. (2013). Red flags to screen for malignancy and fracture in patients with low back pain: systematic review. BMJ (Clinical research ed.), 347, f7095. https://doi.org/10.1136/bmj.f7095
  • Sizer Jr, P. S., Brismée, J., & Cook, C. (2007). Medical screening for red flags in the diagnosis and management of musculoskeletal spine pain. Pain Practice, 7(1), 53 – 71.
  • Verhagen, A. P., Downie, A., Maher, C., & Koes, B. W. (2016). Red flags presented in current low back pain guidelines: a review. European Spine Journal, 25, 2788 – 2802

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