specific problems also decrease the risk of pattern‐based tunnel vision and confirmation bias.
How likely is a diagnosis?
Priority is also influenced by the relative likelihood of a diagnosis. Common things occur commonly. Therefore, although you shouldn’t dismiss the possibility of an unusual diagnosis by any means, the priority for the assessment is usually to consider the most likely diagnoses first, provided they are consistent with the data available.
The problem‐based approach
Problem‐based approach means different things to different people, and you may have already read about or been to courses where it was discussed. Some regard the problem‐based approach as meaning ‘write a problem list, then list every differential possible for every problem.’ Not a feasible task unless you have an amazing factual memory and endless time! Others view the problem‐based approach as meaning ‘write a problem list, then list your differentials.’ This is really just a form of pattern recognition, but at least it makes a good start by formulating a problem list.
The basis of this book is the concept of logical clinical problem‐solving (LCPS). This approach provides steps to bridge the gap between the problem list and the list of differential diagnoses via a structured format. The problems should be investigated by rigorous use of the following questions as illustrated in Figure 2.2:
What is the problem? (Define +/‐ refine the problem – some problems do not need to be refined, others do.)
What system is involved, and how is it involved? (Define and refine the system.)
Where within the system is the problem located? (Define the location.)
What is the lesion? (Define the lesion – the differential list.)
The answers to these questions or the pursuit of the answers will determine the appropriate questions to ask in the history. They may alert you to pay particular attention to aspects of the physical examination, and/or they may indicate the most appropriate diagnostic test to use to find the answers as well as prepare you intellectually to assess the results of diagnostic procedures.
Figure 2.3 Clinical reasoning step‐by‐step: define and refine the problem.
Example: the owner reports that the dog is vomiting. Is the animal really vomiting or regurgitating – or perhaps even coughing or experiencing reflux?
When considering the important clinical signs the patient is exhibiting, it is essential to try to define the problem as accurately as possible. A problem well defined is a problem half solved is a good maxim to work from.
The first question to ask is, Is there another clinical sign that this problem could be confused with? This is a vital step, and failure to define the problem correctly has often derailed a clinical investigation that might otherwise have been relatively straightforward.
Other examples include the following:
The owner says the dog is having fits – is it having seizures, episodes of syncope or vestibular attacks or other strange episodes? (Chapter 8)
The owner says the dog has red urine – is it blood, haemoglobin or myoglobin? (Chapter 12)
Refine the problem
Some (but not all) problems require further refining to clarify the best diagnostic approach.
Examples include the following:
Weight loss – is this because of inappetence or despite a normal appetite? (Chapter 5)
Collapse – with or without loss of consciousness? (Chapters 7 and 8)
Why is it so important to define and refine the problem?
The range of diagnoses to consider, diagnostic tools used and potential treatment or management options for clinical problems that may be perceived by the owner to be the same and present similarly to the veterinarian can be very different. Or the owner might perceive the presenting signs to be attributable to one problem, but in reality, the signs indicate another problem to the veterinarian.
Failure to appropriately define and/or refine the problem can often lead to wasted time and money, as the wrong problem is investigated or treated.
This may:
Delay reaching a feasible diagnosis
Delay treatment
Prolong the disease
Prolong the patient’s suffering
Sometimes potentially endanger the life of the patient
Unnecessarily increase the costs to the client
Frustrate the veterinarian and client
Potentially impair the client–veterinarian relationship.
Figure 2.4 Clinical reasoning step‐by‐step: define and refine the system.
Once the problem is defined, the next step is usually to consider the system involved (Figure 2.4). For every clinical sign, there is a system(s) that must be involved, that is it ‘creates’ the clinical sign – this is what is meant by defining the system. However, the really important question is, How is it involved? This is refining the system. The key questions in this case are What system is involved in causing this clinical sign? (define the system), and Do I have a primary, that is, structural problem of a body system, or a secondary problem, that is, functional problem where the system involved is affected by other factors? (refine the system).
| Key concept | |
|---|---|
| Define the system | For every clinical sign, identify the system that must be involved. |
| Refine the system |
For every defined system, determine how the system is affected – primary (structural) or secondary (functional) or, for some problems, local vs systemic.
|