Red flags in the context of a clinical signal usually relate to a clinical symptom or sign that should make you suspect a more serious diagnosis. Problematically many of the commonly taught red flags can lack sensitivity or specificity, although some have been very well studied from this point of view, and clinicians will face negligence cases if they miss them.
Symptoms, which if present, raise the possibility of serious or treatable disease.
For instance, bladder dysfunction in back pain with bilateral sciaticia should prompt urgent exclusion of cauda equina syndrome by examination for saddle analgesia and onwards urgent imaging. Similarly, some symptoms such as a change in bowel habit or abdominal bloating can non-specifically suggest cancer and may warrant further assessment, even with such low specificity, as they can precede other more specific symptoms by many months. Abdominal pain in the context of hyponatraemia and hypertension suggests screening for acute intermittent porphyria.
Some red flags are:
- Sudden onset never before so severe
- Occipital - consider posterior fossa lesion or if posterior neck tenderness cranial arteritis
- Diurnal pattern
- Scalp tenderness -cranial arteritis
- Young obese female - check for signs of idiopathic intracranial hypertension
Signs, which if present, raise the possibility of serious disease.
For instance, dry axilla as a sign for dehydration in the elderly, carphology (picking at bed clothes) as a sign of delirium, the silent chest in the asthmatic. The erythematous, swollen, warm foot of acute neuropathic arthropathy (ie Charcot foot) in the diabetic.
Investigation results, which if present, raise the possibility of serious or treatable disease.
- Long QT interval
- Interventricular conduction delay (prolonged QRS) and refractory heart failure - consider cardiac resynchronisation therapy
- High total protein and confusion/renal failure- consider electrophoretic strip plasma and urine and calcium