10 axioms to aid your diagnostic skills - DVM
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10 axioms to aid your diagnostic skills


AXIOM 6: Just because two or more events occur in consecutive order do not prove a cause-and-effect relationship.

Unrelated and unforeseen coincidences commonly occur in the lives of all living beings. Therefore, extreme caution must be used in the interpretation of uncontrolled observations. The ability to recognize true cause-and-effect relationships is not an innate characteristic, it must be learned.

The key point is that just because two or more events occur in consecutive order does not prove a cause-and-effect relationship. Consider this example:

In the late 1970s and early 1980s, vesicourachal diverticula were cited as playing an etiologic role in some cats with lower urinary-tract disease (LUTD). Treatment by surgical extirpation was recommended in most veterinary textbooks at that time. The observation that clinical signs subsided coincidentally with diverticulectomy, and lack of studies of the biologic behavior of macrosopic diverticula without surgery, reinforced the interpretation that this anatomic abnormality was a cause of LUTD.

However, subsequent studies of the biological behavior of vesicourachal diverticula revealed that they were a sequela, rather than a cause of LUTDs. Most of them spontaneously resolved with appropriate medical therapy of the underlying problem. Surgery was unnecessary. This example highlights the fact that favorable outcomes associated with our treatments do not prove that our diagnoses were correct, or that our treatments were beneficial.

AXIOM 7: There is a conceptual difference between possibilities and probabilities.

The need to discern that difference is another key medical axiom. In general, numerous diagnostic possibilities are reduced to a few or one diagnostic probability on the basis of proper collection and interpretation of clinical data. However, even after collection of a large quantity of relevant data, many diagnostic probabilities still represent a matter of educated opinion rather than a matter of fact. Absence of clinical evidence of suspected diseases is not always synonymous with evidence of absence of these diseases. It follows that we as veterinarians should convey to our clients that our diagnoses, prognoses and treatment recommendations are not infallible. The practice of veterinary medicine often requires judgment in the absence of certainty.

AXIOM 8: Just as no two individuals are exactly alike in health, so neither are any two in disease.

The concept of a key pathogno- monic finding that will unlock the door to a specific diagnosis is misleading. Rarely will a single historical event, physical exam finding, laboratory test result or radiograph/ultrasound finding provide information of sufficient specificity to warrant a specific diagnosis.

Likewise, memorization of textbook descriptions of characteristic clinical findings of specific diseases is not consistently effective. Why? The same disease typically induces a variety of manifestations of different degrees of severity in different patients. Most textbook descriptions are abstracts of prototypical disease features, all of which often do not coexist in the same patient. Just as no two individuals are exactly alike in health, so neither are any two in disease.

AXIOM 9: Diseases often are self-limiting.

The severity of many diseases subsides in a day or two. In this situation, any treatment may appear to be bene- ficial as long as it is not harmful.

AXIOM 10: There are some patients we cannot help, but there are none we cannot harm.

Especially when we are overconfident, and when saving face is more important than saving lives. We all can extinguish life. However, who among us can create life?

Not all diagnoses created equal

Are their conceptually different levels of diagnoses? Not all diagnoses are equal in terms of their prognostic and therapeutic implications.

Based on results obtained from a variety of sources, including: 1) the patient's history, 2) the physical examination, 3) various laboratory tests, 4) radiography and other methods of diagnostic imaging, 5) endoscopy, 6) biopsy, and/or 7) exploratory surgery, we recommend that clinical problems be classified into one of four progressive levels of refinement. Listed from the lowest to the highest level of refinement, problems may be diagnosed as:

1. An unquantified (subjective) symptom or clinical finding (e.g., depression, polydipsia, polyuria, or vomiting). If the problem(s) is mild and transient, treatment my not be warranted. However, if clinical signs are severe, persistent or progressive, further information is often warranted to identify its source/cause, and to formulate a prognosis and treatment plan.


Source: DVM360 MAGAZINE,
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