I have always found the diagnosis of trichomoniasis a difficult one to deal with.

Not personally of course! I am more thinking about the best approach to this issue in the laboratory…

Up until now we have been looking for Trichomonas vaginalis in every single one of the 50,000+ vaginal swabs we get into our laboratory per year.

The vaginal swabs more often than not land on our doorstep with no (clinical) indication as to why they have been sent to us. 

To me this is old style medical/laboratory practice… We need to move away from diagnosing the swab per se, just as clinicians need to move away from treating the lab result on its own , without thinking about the patient.

There are essentially three main ways to diagnose Trichomonas vaginalis:

• Wet film or other related direct microscopy method: Cheap but very insensitive
• Culture: usually in micro-titre plates: More sensitive but still not great. Still cheap though
• Nucleic acid amplification, e.g. PCR: Very sensitive, but also expensive.

More and more laboratories are moving towards the molecular methods, but we (and others) simply cannot afford to test 50,000 vaginal swabs for Trichomonas vaginalis by PCR. 

Nor would it be a good use of financial resources…

So, out of necessity, the laboratory needs to move towards targeted testing; e.g. high risk age groups, sexual health clinics, on specific request, appropriate clinical details, etc.

And therein lies the dilemma – You will pick up more cases because you are using a more sensitive test, but the overall number of diagnoses might be similar because you are testing less patients.

But my gut instinct tells me that the latter approach of targeted testing (based on patient symptoms and risk factors) using the optimal test is the way of the future. Not to mention it also allows the capability to test men as well! (Trying to diagnose trichomoniasis in men using traditional microscopy and culture is virtually impossible.)

Sometimes you just have to throw the old rule book out the window and start again…

Michael

Picture courtesy of GiantMicrobes.com !