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 17.1.
Table 17.1The diagnostic model for a presenting problem |Favorite Table|Download (.pdf) Table 17.1 The diagnostic model for a presenting problem
|1 ||What is the probability diagnosis? |
|2 ||What serious disorders must not be missed? |
|3 ||What conditions are often missed (the pitfalls)? |
|4 ||Could this patient have one of the ‘masquerades’ in medical practice? |
|5 ||Is this patient trying to tell me something else? |
This approach, which is 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.
Each of the above five questions will be expanded.
An excellent acronym on this theme, ‘PROMPT’, was devised by a reader, Dr Kelly Teagle:
R Red flag
O Often missed
P Patient wants to
T Tell me something
Another contribution is by Flinders University medical student, Judah:
Things are not always cut and dried:
C Connective tissue disorders
U UTIs, particularly in very old and very young
T Thyroid disease
R remember to Rule out serious and Rare causes
I Iatrogenic causes
E Emotional needs
1 The probability diagnosis
The probability diagnosis is based on the doctor's perspective and experience with regard to prevalence, incidence and the natural history of disease. GPs acquire first-hand epidemiological knowledge about the patterns of illness apparent in individuals and in the community, which enables them to view illness from a perspective that is not available to doctors in any other disciplines. Thus, during the medical interview, the doctor not only is gathering information, allocating priorities and making hypotheses, but also is developing a probability diagnosis based on acquired epidemiological knowledge.
2 What serious disorders must not be missed?
While epidemiological knowledge is a great asset to the GP, it can be a disadvantage in that he or she is so familiar with what is common that the all-important rare cause of a presenting symptom may be overlooked. On the other hand, the doctor in the specialist clinic, where a different spectrum of disease is encountered, is more likely to focus on the rare at the expense of the common cause. However, it is vital, especially working in the modern framework of a litigation-conscious society, not to miss serious, life-threatening disorders.
To achieve early recognition of serious illness, the GP needs to develop a ‘high index of suspicion’. This is generally regarded as largely intuitive, but this is probably not the case, and it would be more accurate to say that it comes with experience.
The serious disorders that should always be considered ‘until proven otherwise’ include malignant disease, acquired immunodeficiency syndrome (AIDS), coronary disease and life-threatening infections such as meningitis, meningococcal infection (see FIG. 17.1), Haemophilus influenza b infections, septicaemia and infective endocarditis (see TABLE 17.2).
Meningococcal infection: complications of infarction (DIC) including gangrene from meningococcaemia
Table 17.2Serious ‘not to be missed’ conditions |Favorite Table|Download (.pdf) Table 17.2 Serious ‘not to be missed’ conditions
|Neoplasia, especially malignancy |
|HIV infection/AIDS |
|Severe infections, especially: |
meningococcal infection (see Fig. 17.1)
clostridia infections, e.g. tetanus, botulism, gas gangrene
|Coronary artery disease |
|Imminent or potential suicide |
|Intracerebral lesions (e.g. subarachnoid haemorrhage) |
|Ectopic pregnancy |
Myocardial infarction or ischaemia is extremely important to consider because it is so potentially lethal and at times can be overlooked by the busy practitioner. It does not always manifest as the classic presentation of crushing central pain but can present as pain of varying severity and quality in a wide variety of sites. These sites include the jaw, neck, ear, arm, epigastrium and interscapular region. Coronary artery disease may manifest as life-threatening arrhythmias that may present as palpitations and/or dizziness. A high index of suspicion is necessary to diagnose arrhythmias.
Diagnostic triads for life-threatening conditions (examples)
DxT fever + rigors + hypotension ➜ septicaemia
DxT fever + vomiting + headache ➜ meningitis
DxT fatigue + dizziness ± syncope ➜ cardiac arrhythmia
DxT fever + drooling + stridor (child) ➜ epiglottitis
DxT headache + vomiting + altered consciousness ➜ subarachnoid haemorrhage (SAH)
DxT abdominal pain + amenorrhoea + abnormal vaginal bleeding ➜ ectopic pregnancy
DxT fatigue + dyspnoea on exertion + dizziness ➜ cardiomyopathy
A traditional way of classifying serious diseases is the pathology aide-mémoire:
Red flags (alarm bells) are symptoms or signs that alert us to the likelihood of significant harm. Such underlying disease must not be missed and demands careful investigation. Examples include weight loss, vomiting, altered cognition, fever >38°C, dizziness, and/or syncope at the toilet and pallor. Red flags will be outlined under presenting symptoms throughout the text.
3 What conditions are often missed?
This question refers to the common ‘pitfalls’ so often encountered in general practice. This area is definitely related to the experience factor and includes rather simple, non-life-threatening problems that can be so easily overlooked unless doctors are prepared to include them in their diagnostic framework.
Classic examples include smoking or dental caries as a cause of abdominal pain, allergies to a whole variety of unsuspected everyday contacts, foreign bodies, occupational or environmental hazards as a cause of headache, respiratory discomfort or malaise, and faecal impaction as a cause of diarrhoea. We have all experienced the ‘red face syndrome’ from a urinary tract infection, whether it is the cause of fever in a child, lumbar pain in a pregnant woman or malaise in an older person. The dermatomal pain pattern caused by herpes zoster prior to the eruption of the rash (or if only a few sparse vesicles erupt) is a real trap.
A typical pitfall is Addison disease, where some patients can wait up to 15 years before being diagnosed. The absence of subdued classic pigmentation (see FIG. 17.2) can mask the early diagnosis.
Woman with Addison disease showing facial pigmentation
Haemochromatosis can be a surprise diagnosis, often discovered by serendipity following a screening blood test for unexplained fatigue. Coeliac disease is a classic master of disguise in both children and adults. It now ranks as one of the most common, widespread and undiagnosed illnesses affecting humans. In Australia, 1.5% of the population are affected but 80% remain undiagnosed.4 Research by dermatologists5 has highlighted that it can present in a number of ways that can affect the skin and hair. Apart from typical gastrointestinal symptoms, such as chronic diarrhoea, steatorrhoea, weight loss, anorexia and abdominal distension, the following atypical symptoms have been described:
nutritional presentations, including folate, zinc or iron (in particular) deficiency
grouped blisters around the knees, elbows and buttocks (dermatitis herpetiformis)
hair loss and mouth ulcers
Menopausal symptoms can also be overlooked as we focus on a particular symptom. Some important pitfalls are given in TABLE 17.3.
Table 17.3Classic pitfalls |Favorite Table|Download (.pdf) Table 17.3 Classic pitfalls
|Abscess (hidden) |
|Addison disease |
|Candida infection |
|Chronic fatigue syndrome |
|Coeliac disease |
|Domestic abuse, including child abuse |
|Drugs (see TABLE 17.4) |
|Faecal impaction |
|Foreign bodies |
|Herpes zoster |
|Lead poisoning |
|Malnutrition (unsuspected) |
|Menopause syndrome |
|Migraine (atypical variants) |
|Paget disease |
|Pregnancy (early) |
|Seizure disorders |
|Tourette syndrome |
|Urinary infection |
Diagnostic triads for some ‘pitfalls’
DxT fatigue + weight loss + diarrhoea ➜ coeliac disease
DxT anorexia/nausea + faecal leaking + abdominal bloating ➜ faecal impaction
DxT abdominal cramps + flatulence + profuse diarrhoea ➜ giardiasis
DxT lethargy + tiredness + arthralgia ➜ haemochromatosis
DxT lethargy + abdominal pains + irritability (in child) ➜ lead poisoning
DxT aching bones + waddling gait + deafness ➜ Paget disease
DxT malaise + cough + fever (± erythema nodosum) ➜ sarcoidosis
DxT (male child) snorting, blinking + oral noises (e.g. grunts) ± loud expletives ➜ Tourette syndrome
4 The masquerades (‘chameleons’)
It is important to utilise a type of fail-safe mechanism to avoid missing the diagnosis of these disorders. Some practitioners refer to consultations that make their ‘head spin’ in confusion and bewilderment, with patients presenting with a ‘shopping list’ of problems. It is in these patients that a checklist is useful. Consider the apparently neurotic patient who presents with headache, lethargy, tiredness, constipation, anorexia, indigestion, shortness of breath on exertion, pruritus, flatulence, sore tongue and backache. In such a patient we must consider a diagnosis that links all these symptoms, especially if the physical examination is inconclusive; this includes iron deficiency anaemia, depression, diabetes mellitus, hypothyroidism (see FIG. 17.3) and drug abuse.
Hypothyroidism in a 60-year-old woman, a classic masquerade, with a slow subtle onset of facial changes
A century ago it was important to consider diseases such as syphilis and tuberculosis as the great common masquerades, but these infections have been replaced by iatrogenesis, malignant disease, alcoholism, endocrine disorders and the various manifestations of atherosclerosis, particularly coronary insufficiency and cerebrovascular insufficiency.
If the patient has pain anywhere it is possible that it could originate from the spine, so the possibility of spinal pain (radicular or referred) should be considered as the cause for various pain syndromes, such as headache, arm pain, leg pain, chest pain, pelvic pain and even abdominal pain. The author's experience is that spondylogenic pain is one of the most underdiagnosed problems in general practice.
A checklist that has been divided into two groups of seven disorders is presented in TABLES 17.4 and 17.5. The first list, ‘the seven primary masquerades’, represents the more common disorders encountered in general practice; the second list includes less common masquerades—although some, such as Epstein–Barr mononucleosis, can be very common masquerades in general practice.
Table 17.4The seven primary masquerades |Favorite Table|Download (.pdf) Table 17.4 The seven primary masquerades
|1 ||Depression |
|2 ||Diabetes mellitus |
|3 ||Drugs |
|4 ||Anaemia |
|5 || |
Thyroid and other endocrine or metabolic disorders
|6 ||Spinal dysfunction |
|7 ||Urinary tract infection (UTI) |
Table 17.5The seven other masquerades |Favorite Table|Download (.pdf) Table 17.5 The seven other masquerades
|1 ||Chronic kidney failure |
|2 ||Malignant disease |
|3 ||HIV infection/AIDS |
|4 ||Baffling bacterial infections |
|5 ||Baffling viral (and protozoal) infections |
TORCH organisms (e.g. cytomegalovirus)
hepatitis A, B, C, D, E
– Ross River fever
– dengue fever
|6 ||Neurological dilemmas |
|7 ||Connective tissue disorders and the vasculitides |
Neoplasia, especially malignancy of the so-called ‘silent areas’, can be an elusive diagnostic problem. Typical examples are carcinoma of the nasopharynx and sinuses, ovary, caecum, kidney and lymphoietic tissue. Sarcoidosis is another disease that can be a real masquerade (see CHAPTER 49).
Systemic lupus erythematosus (SLE) has been described as ‘the great pretender’.6 The two most common symptoms are joint pain and fatigue but it is a multisystem disease that may present with involvement of any of these organ systems and may not initially be recognised as such.
As a practical diagnostic ploy, the author has both lists strategically placed on the surgery wall immediately behind the patient. The lists are rapidly perused for inspiration should the diagnosis for a particular patient prove elusive.
5 Is the patient trying to tell me something?
The doctor has to consider, especially in the case of undifferentiated illness, whether the patient has a ‘hidden agenda’ for the presentation.7 Of course, the patient may be depressed (overt or masked) or may have a true anxiety state. However, a presenting symptom such as tiredness may represent a ‘ticket of entry’ to the consulting room.3 It may represent a plea for help in a stressed or anxious patient. We should be sensitive to patients’ needs and feelings, and, as listening, caring, empathetic practitioners, provide the right opportunity for the patient to communicate freely.
Deep sexual anxieties and problems, poor self-esteem, and fear of malignancy or some other medical catastrophe are just some of the reasons patients present to doctors.
The patient with a self-induced bruising (see FIG. 17.4) was a health professional who was deeply attracted to an inpatient haematologist (Munchausen syndrome).
Artefactual purpura showing an unusually symmetrical distribution in sites that can be reached by the patient (a ‘ticket of entry’)—Munchausen syndrome
The author has another checklist (see TABLE 17.6) to help identify the psychosocial reasons for a patient's malaise.
Table 17.6Underlying fears or image problems that cause stress and anxiety |Favorite Table|Download (.pdf) Table 17.6 Underlying fears or image problems that cause stress and anxiety
|1 ||Interpersonal conflict in the family |
|2 ||Identification with sick or deceased friends |
|3 ||Fear of malignancy |
|4 ||STIs, especially AIDS |
|5 ||Impending ‘coronary’ or ‘stroke’ |
|6 ||Sexual problem |
|7 ||Drug-related problem |
|8 ||Crippling arthritis |
|9 ||Financial woes |
|10 ||Other abnormal stresses |
Diagnostic triads for some ‘masquerades’
DxT malaise + fever + cough (± erythema nodosa) ➜ TB or sarcoidosis
DxT fever + sore throat + cervical lymphadenopathy ➜ EB mononucleosis
DxT fatigue + a/n/v + sallow skin ➜ chronic kidney failure
DxT polyuria + polydipsia + skin/orifice infections ➜ diabetes mellitus
DxT FUO + cardiac murmur + embolic phenomena ➜ infective endocarditis
DxT fatigue + polyarthritis + fever or skin lesions ➜ SLE
DxT loin pain + haematuria + palpable loin mass ➜ kidney carcinoma
DxT malaise + weight loss + cough ➜ lung carcinoma
DxT fever + myalgia/headache + non-productive cough ➜ atypical pneumonia
DxT malaise + night sweats + painless lymphadenopathy ➜ non-Hodgkin lymphoma
DxT arthralgia + Raynaud phenomenon + GORD (± skin changes) ➜ systemic sclerosis
DxT fatigue + headache + jaw claudication ➜ temporal arteritis
DxT weakness + back pain + weight loss ➜ multiple myeloma
DxT lethargy + physical/mental slowing + constipation ➜ hypothyroidism
Note: Diagnostic triads for neurological dilemmas are included in CHAPTER 33.
In the author's experience of counselling patients and families, the number of problems caused by interpersonal conflict is quite amazing and makes it worthwhile to specifically explore the quality of close relationships, such as those of husband–wife, mother–daughter and father–son.
Another common yet overlooked stressor is bullying,8 whether it is in the workplace, school, university, home, internet or elsewhere. It is a significant public health issue. The current fashion for tough, dynamic, ‘macho’ management styles has created a culture in which bullying can thrive. As GPs we should be more aware of the possibility that workplace bullying may be contributing to the stresses with which many patients present. A simple, direct, routine question such as ‘How are things at work?’ can create an opportunity to raise the issue.
Identification and transference of illness, symptoms and death, in particular, are important areas of anxiety to consider. Patients often identify their problems with relatives, friends or public personalities who have malignant disease. Other somatoform disorders and the factitious disorders, including the fascinating Munchausen syndrome, may be obvious or extremely complex and difficult to recognise. Consider also ‘Munchausen by proxy’ where carers intentionally produce or feign symptoms in the person (child or elderly patient) in their care. These subtle psychosocial issues are usually termed ‘yellow flags’.
Yellow flags are signs or behaviours that flag or indicate a psychosocial barrier to recovery. They have been described originally within the framework of chronic pain and disability, especially chronic back pain, and require a shift in our focus of care. Conditions to consider are anxiety, depression, adjustment disorder and personality disorder. Typical yellow flags are presented in TABLE 17.7.
Table 17.7Yellow flags: examples |Favorite Table|Download (.pdf) Table 17.7 Yellow flags: examples
|Abnormal illness behaviour |
|Devious behaviour |
|Cancelling appointments |
|Treatment non-compliance/refusal |
|Absenteeism from work |
|Poor work performance |
|Personal neglect |
|Relationship breakdown |
|Law and order incidents |
A survey by researchers at Melbourne's Centre for Behavioural Research9 revealed that the three most feared diseases are cancer (81%), heart disease (32%) and HIV/AIDS (21%).
The bottom line is that patients are often desperately searching for security and we have an important role to play in helping them.