Tag Archives: focused requesting

“I told you I was sick”

The Science of Microbiology, , ,

Patient: “I have just come back from Bali and I have a fever and joint pains.”

Doctor: “Not to worry, I think you might have Dengue. I will do a blood test now, and another one in a month’s time to see if I am right.”

Patient: “Just a month, oh, it can’t be too serious then…”

Doctor: “No, it’s just Dengue, and what’s more I have some good news for you, I have just got some results back from the laboratory, that other illness you had 6 weeks ago turned out to be Legionella after all.”

Patient: “I told you I was sick…”

Even in the molecular age, it is surprising how often acute and convalescent serological testing is still utilised in clinical practice. Acute and convalescent serology is still frequently used for Legionella diagnosis, Dengue and other arboviruses, Lyme disease, Leptospirosis, the list goes on…

There are several potential reasons for this:

  • Requestor is used to ordering acute and convalescent serology-This is what the requestor has been doing for the past 30 years. Why change now?
  • Requestor is not aware that other options are available.- The requesting clinician may not be aware of the other options that are available for that particular condition, e.g PCR, antigen testing, etc.
  • Requestor scared/unaware they are allowed to order more “exotic” tests.- I find this a particular challenge when dealing with requests from the community setting. “I didn’t realise we were allowed to request a PCR test for this condition.”
  • Alternatives perceived to be more expensive.- And they are to a certain extent, particularly for arboviruses, but less so for Legionella. But don’t forget that 2 sets of serology along with the time for labour, interpretation and reporting is not an insignificant cost by any means.
  • Laboratory continues to offer acute and convalescent serology.- The laboratory can be guilty too, of not placing appropriate restrictions on acute and convalescent serology. The lab managers and clinical microbiologists of today are often  from an era where acute and convalescent serology was a mainstay of “diagnosis”.

If you were building a microbiology laboratory from scratch, and compiling a schedule or menu of tests, I would like to think acute and convalescent serology would be very low on the priority list.

There may be Public Health reasons why you might want to (retrospectively) confirm the diagnosis with acute and convalescent serology, but if this is the case, then it should be requested (or approved by) by Public Health doctors.

However for the purposes of acutely diagnosing the patient, by the time you get the result, the patient has either recovered, or not recovered…

Better to carefully restrict access to acute and convalescent serology, and “push” requestors into trying to make a real time diagnosis with more modern tests. The patient will thank you for it…

Michael

 

“The Shopping List”

Confessions of a Microbiologist, ,

shopping list

Take the following hypothetical list of laboratory tests:

  • FBC
  • U&Es
  • LFTs
  • Thyroid Function tests
  • Hepatitis A, B & C screen
  • HIV
  • Treponemal screen
  • ANA
  • Coagulation screen
  • Complement
  • Autoantibody screen
  • EBV serology
  • CMV serology
  • Urine culture
  • MRSA screen
  • Serum lipids

In laboratories across the world, this kind of “shopping list” request form coming into the laboratory is seen all too frequently, and often without any clinical justification or rationale included.

Add up the costs of these tests and you have a total of several hundred dollars, maybe even over a thousand. A CT scan would be roughly an equivalent cost, and you would be hard pushed to get one of those without justifying exactly why you wanted it….

There may of course be a very valid reason for ordering all the tests above, although it is difficult to think of a clinical syndrome which would justify everything in the list above.

Such a list may be done as a “wellness screen”, but whether you believe in wellness screening or not, there are tests in here (EBV, CMV, urine culture for starters) which should never be part of any wellness screen laboratory testing.

Such a list may be done as a “fishing expedition” when the patient presents to the clinician with vague or ill defined symptoms. The problem is that the prevalence rates for most of these tests in such patient populations are going to be very low with the consequent problems of low positive predictive value and false positive results.

Personally I don’t believe that shopping list requests such as the above that are sent into the lab by clinicians should be permitted unless there is a clear rationale on the request form detailing why so many tests have been requested in the first place…..

Courtesy, respect, and common sense.

Michael

Of course if your laboratory is on a fee for service funding arrangement you might welcome “shopping lists” or at least turn a blind eye to them…. Personally however I have never been a great fan of shopping!