Our mantra – CCMM

As GP educators and authors of Complete CSA, we would like to share with you our experience as clinicians and guide you towards best practice to enable you to thrive and fulfil your full potential as a future Specialist Generalist.

Those who have read Complete CSA will know that our motto is:

“Common things are common but what mustn’t I miss? ” (CCMM)

Let us explain why.

There are many resources listing differential diagnoses, investigations and red flags. There is, however, a real risk that the uncommon conditions at the bottom of the differential list may be forgotten. They may not be emergencies or life limiting illnesses, which are detected by red flags or examination findings, yet remain important diagnoses. Furthermore, if you haven’t taken a thorough history to filter the spectrum of differentials, then starting with first line investigations may delay diagnosis.

We suggest you use these resources to challenge your clinical decision making. As part of your revision, when considering each presenting symptom, ask yourself the following 7 questions:

1) What mustn’t I miss?

2) What misdiagnoses are possible?

3) How might each of these conditions present?

4) What are the risks of missing each condition?

5) What other symptoms/signs do I need to rule out for each differential?

6) What tests do I need to do and what is an appropriate timescale?

7) What must I document?

GPs may well start at the top of each list of differentials and investigate what is common and probable. This is often pragmatic – it prevents over-investigation and many conditions are not urgent. Mild symptoms may justify a stepwise approach and of course time is an important diagnostic tool.

It is therefore good practice to regularly remind yourself of the conditions that may one day quietly creep, perhaps unnoticed, through your consulting room door.

Reasons the busy generalist may be at risk of missing an uncommon diagnosis

– Not considering it in the first place.

– Dependence on red flags. Red flag lists are not complete and are aimed at life threatening disease only.

– Low probability of uncommon and rare disease.

– Time pressures.

– Belief the patient should have initial tests and will come back if necessary.

– Belief that rare diagnoses are for specialists.

– Pressures not to waste NHS resources and over investigate.

– More experienced GPs may encourage trainees to shake off their trainee diligence and thoroughness, to ‘get on with the job.’

– Longstanding familiarity with a patient may miss what fresh eyes would notice.

– Patients may struggle to articulate their symptoms. (Which is why learning good consultation skills is so important!)

– New symptoms may be hidden within the depths of comorbidity or concealed by the web of all the patient’s myriad symptoms.

– There is a wellness bias in general practice. Our access to diagnostic tests is limited or slow and we usually “make the call” based on experience and judgment, not tests. For example, a patient who walks into a hospital with chest pain will inevitably get a troponin test. GPs cannot do this and know it is not always appropriate – though we carry the risk of being wrong.

– A single consultation is a snapshot in time. Diseases evolve. You may see a patient in the early stage of their disease before symptoms or signs have declared themselves. This is why we use safety nets and bring patients back.

All of these factors are real, however none are excuses to not consider the spectrum of possibilities from the outset.

It is impossible to know everything….

….therefore, all we can do is try to balance the challenges of our work with life. We suggest looking at some low-down differentials and ask yourself, would I miss it? If the answer is ‘possibly’, use the CCMM model for your personal development.

It is not appropriate to consider the whole differential diagnosis list in every consultation. Our point is that it is your duty not to let this become a faded memory so that when the day arrives, you are prepared for it and, even in the first consultation, you may be able to take a more direct route to the diagnosis.


GPs use knowledge, experience and judgement to avoid over-investigation so that NHS resources can be optimally used. In doing this, we carry risk and GPs can feel overwhelmed with this responsibility. We are all aware that we may trip during our career path and that both we and our patients may suffer the consequences.

Trainees or NQGPs do not yet have the wisdom of experience, gained by seeing patients over 40 years. Times are also changing… New GPs document more than their predecessors; important positive and negative findings, thoughts and advice including safety netting. Spiralling Indemnity cover, increasingly frequent medicolegal challenges and the recognition that diseases evolve, are all good reasons to justify “defensive practice”. If you have been wise enough to uncover clues that lead you through the diagnostic process, then for the benefit of the patient, the next doctor and to protect yourself, document this! Can you type fast? If not, learn to do so! Diligence ensures that at the time of the consultation, both the patient and GP are reassured that a thorough assessment has been under taken and recorded.

Be prepared for the day the uncommon walks through the door! Remember – CCMM.