Chapter 9: A safe diagnostic model

INTRODUCTION

The discipline of general practice is probably the most difficult, complex and challenging of all the healing arts. Our field of endeavour is at the very front line of medicine and as practitioners 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.

The teaching of our craft is also an exciting challenge and presupposes that we have a profound comprehension of our discipline.

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 or vague symptoms—the so-called undifferentiated illness syndrome.¹ Common undifferentiated symptoms include tiredness or fatigue, sleeping problems, anxiety and stress, dizziness, headache, indigestion, anorexia and nausea, sexual dysfunction, weight loss, loss of interest, flatulence, abdominal discomfort and chest discomfort.² 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.

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

THE CONCEPT OF DIAGNOSTIC TRIADS

A most useful guide to learning or memorising diagnoses, especially of elusive and uncommon conditions, is to remember three key points to the condition. The cognitive process of learning these so-called ‘triads’ and even ‘tetrads’ provides a useful template for the diagnostic methodology required in general practice. Some simple examples are shown in the following box.

Examples such as these are interspersed throughout the text, especially in this chapter, and are prefixed by the symbol DxT.

THE BASIC MODEL

The use of the diagnostic model requires a disciplined approach to the problem with the medical practitioner quickly answering five self-posed questions. The questions are shown in TABLE 9.1.