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The stories told in this book demand that general practitioners have an incisive, detective-like approach to our discipline, which is arguably the most difficult, complex and challenging of the healing arts. Our field of endeavour is at the very front line of medicine and, as practitioners of first contact, we shoulder the responsibility of the early diagnosis of very serious, perhaps life-threatening, illness in addition to the recognition of anxiety traits in our patients.

Over and over again the old medicine adage ‘More things are missed by not looking than by not knowing’ has been stressed. However, our area is characterised by a wide kaleidoscope of presenting problems, often foreign to the classic textbook presentation and sometimes embellished by a ‘shopping list’ of seemingly unconnected problems—the so-called undifferentiated illness syndrome. It is important, especially in a busy practice, to adopt a fail-safe strategy to analyse such presenting problems. Such an approach is even more important in a world of increasing medical litigation and specialisation.

It has been estimated that the diagnostic error rate in a general practice setting is 10–15 per cent. Fortunately most of these errors do not cause harm to patients, but some do. Indeed, diagnostic error is the underlying cause of approximately half of the medical negligence claims involving Australian GPs.

For the individual GP, building knowledge and knowledge organisation are important means of reducing diagnostic error. Some of the ways in which to reduce diagnostic errors include:

  • building and strengthening the repository of illness scripts

    • – knowledge of atypical presentation of diseases

    • – symptom-based and case report reading

  • ‘thinking about your thinking’

    • – what else could this be?

    • – what finding doesn’t fit with my diagnosis?

    • – is there any reason to slow down?

  • acknowledge emotions

    • – external demands

    • – internal stresses

    • – emotions stemming from patient interactions

  • reducing reliance on memory

    • – use of checklists, clinical references and/or clinical decision support tools.

To help bring order to the jungle of general practice problems, the author has developed a simple model to facilitate diagnosis and reduce the margin of error.


The use of the diagnostic model requires a disciplined approach to the problem, with the medical practitioner having to quickly answer five self-posed questions. The questions, for a particular patient, are as shown in the box on the next page.

This approach, based on considerable experience, requires the learning of a predetermined plan, which naturally would vary in different parts of the world but would have a certain universal application in the so-called developed world.

The diagnosis model for a presenting problem

  1. What is the probability diagnosis?

  2. What serious disorder(s) must not be missed?

  3. What conditions are often missed (the pitfalls)?

  4. Could this patient have one of the ‘masquerades’?

  5. Is this patient trying to ...

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