“The Requesting Pyramid”

In many laboratories, clinical details on request forms can be structured into a pyramid shape as below.

Let’s take the example of otitis externa.

A good proportion of request forms will be at the bottom of the pyramid, where there are no clinical details present to suggest that otitis externa is the clinical suspicion (as opposed to otitis media, cellulitis of the pinna, or some other condition). Also included in this category are cases where clinical details have been included but are unrelated to sample type, e.g. an ear swab sent with clinical details of “sore throat”. This scenario happens in all sample types with disturbing frequency… (e.g. mid-stream urine sent for a patient with clinical details of chest pain!)

The next level up in the pyramid is where clinical details are present but are insufficient to justify the sample being sent to the laboratory. For example the clinical details might state “Otitis externa“. However most patients with straightforward otitis externa do not need an ear swab sent to the laboratory. Laboratory culture of an ear swab in clinically suspected otitis externa should be the exception as opposed to the rule…

The top level of the pyramid is where clinical details are not only present, but they also give a sound rationale as to why the laboratory is receiving a sample. e.g. “Recalcitrant otitis externa not responding to topical treatment.” or “Diabetic with painful inner ear and fever, clinical suspicion of malignant otitis externa“.

This requesting pyramid applies to most different sample types and clinical scenarios.

At my laboratory, we are doing our utmost to turn this pyramid on it’s head. We have made significant progress to date. In fact our pyramid is starting to look more like a rectangle.

By the end of the year we hope to have removed the base of the pyramid altogether by adopting a policy of having accompanying clinical details pre-requisite for all microbiology tests. I.e. No clinical details, no test.

And that is the way it should be…


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