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Red flag waves in the wind

Red flags

The term ‘red flag’ was historically associated with symptoms of back pain [1]. In modern healthcare the term can be applied to any sign or symptom that might indicate more serious pathology, within any body system. Red flags are useful in general practice as practitioners are expected to have a broad knowledge base and hence indicators of serious underlying illness can help minimize the risk of missing something more serious.

This approach to medicine is not without its critics, with some saying that red flags have limited practical value in detecting serious pathology [2]. Additionally, there is sometimes confusion with regards to red flags, as different guidelines may refer to different sets of red flags for the same presentation. Guidelines generally provide no information on the diagnostic accuracy of a particular red flag, which can limit their value in clinical decision-making [3].

Despite this, red flags can be useful when deciding the urgency and or priority with which we treat a patient. Some red flags like weight loss and reduced appetite, are general in nature and could be due to many pathologies. Other red flags such as hematemesis and melena for example, are specific red flags which indicate bleeding in the gastro-intestinal tract [4]. As a general rule, red flags can help us to decide whether a referral needs to be made immediately, urgently (within 2 weeks) or routinely (beyond 2 weeks).

Red flags are often picked up during the history taking and/or physical examination of the patient. In the context of remote consultations, taking a thorough history becomes even more important, as opportunities for physical examination are limited.


In this step we will focus on the red flags ONLY associated with COVID-19, as an example of how red flags can be used to decide the urgency of treatment. Follow the link below to access a guide to remote consultations for COVID-19 produced by the British Medical Journal:

https://www.bmj.com/content/bmj/suppl/2020/03/24/bmj.m1182.DC1/gret055914.fi.pdf [5].

Please note that whilst this infographic (as with many resources related to the pandemic) is not clinically validated, it does illustrate some useful information.

Look through the stages 1-6 and pay close attention to the clinical characteristics and red flags down the right-hand side.

You may have noticed that within stage 6, it advises clinicians to arrange follow-up for patients who may have pneumonia. This is of course sound advice. You will notice that the urgency with which patients are referred, depends on their clinical observations (vital signs) where available. This information aligns with the Centre for Evidence Based Medicine’s ‘Rapid diagnosis of community-acquired pneumonia for clinicians’ guidance:


Observations (vital signs) such as:

  • Temperature > 38°C
  • Respiratory rate > 20 breaths per minute
  • Heart rate > 100 beats per minute, with new confusion
  • Oxygen saturation ≤ 94%

could indicate severe pneumonia and even sepsis. In the next step we will look in more detail at sepsis, a potentially life-threatening complication of infection.

[1] Welch, E., 2011. Red flags in medical practice. Clinical medicine, 11(3), p.251.

[2] Henschke, N et al. 2009. Prevalence of and screening for serious spinal pathology in patients presenting to primary care settings with acute low back pain. Arthritis & Rheumatism: Official Journal of the American College of Rheumatology, 60(10), pp.3072-3080.

[3] Koes, B.W et al, 2010. An updated overview of clinical guidelines for the management of non-specific low back pain in primary care. European Spine Journal, 19(12), pp.2075-2094.

[4] Ramanayake, R.P.J.C. and Basnayake, B.M.T.K., 2018. Evaluation of red flags minimizes missing serious diseases in primary care. Journal of family medicine and primary care, 7(2), p.315.

[5 BMJ. Covid-19: remote consultations A quick guide to assessing patients by video or voice call [online]. 2020 [cited July 2020]

[6]CEBM. Rapid diagnosis of community-acquired pneumonia for clinicians’ guidance [online]. 2020 [cited July 2020].

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Conducting Remote Consultations and Triage

UCL (University College London)