Lower back pain (also known as lumbago) is very common and is often referred for imaging. However, the vast majority of cases are due to benign self-limiting causes which do not require imaging and resolve with conservative measures. Numerous authors have described various methods for supporting appropriate imaging for the investigation of lumbar back pain. One such system utilizes the idea of red flags and yellow flags.

Red flags

Red flags are patient signs, symptoms or history that indicate possible serious pathology and hence support the decision to image the lower back. If no red flags are present, there is a negligible risk of serious pathology and the patient can be reassured that imaging is not indicated and treated with conservative measures.

Red flags include:

• recent significant trauma

• (prolonged or systemic) glucocorticoid use

• osteoporosis

• age <20 or >55 years

• radiculopathy (radiating pain with a dermatomal distribution pattern)

• bladder or bowel dysfunction

• severe or progressive sensory or motor disturbance

• history of malignancy

• unexplained weight loss

• pain worse at night or at rest

• fever/chills/fatigue

• immune compromise

• intravenous drug use (IVDU)

• history of inflammatory arthritis, enthesitis or uveitis

• morning stiffness or improvement with movement

• thoracic pain

A useful mnemonic can be found here.

Yellow flags

Yellow flags are psychosocial patient factors that although not associated with serious organic pathology nonetheless indicate an increased likelihood of chronic back pain and resultant long term disability and potential loss of work.

Yellow flags include:

• a belief that pain and activity is harmful or severely disabling

• fear-avoidance behavior

• sickness behaviors

• low mood

• social withdrawal

• the expectation that passive treatment rather than active participation will help

• issues with the compensation system

• poor job satisfaction

• difficulty at work

• overprotective family

• lack of social support

• financial problems

• somaticizing tendency