Rules and Algorithms
Just the other day a question of how to alert physicians of laboratory reflex rules came up. After all, everyone's rules are slightly different.
Examples: if the dipstick is positive for blood or leukocyte esterase, perform a microscopic examination of urine sediment; if the triglycerides are elevated, perform a direct LDL cholesterol measurement; if a screen for unexpected antibodies is positive, perform an antibody identification. These "if-then" rules are simple enough.
But many are more complex. A culture reflex based on a microscopic is subjective and variable if based on the number of white cells seen. There may be rejection criteria based on the number of squamous epithelial cells. While this may meet a physician's general expectation to "Culture if indicated," it's a broad net that will capture a lot of contamination and miss a few true positives.
Physician expectations and laboratory rules may collide. Catheterized specimens are often thought better – are they? An indwelling catheter can result in treating the catheter, and a straight catheter scoops up everything in its path. OB/GYN docs may order cultures on asymptomatic patients, resulting in "more" contamination.
Our rules, which are designed for symptomatic patients with a florid response who are able to collect a clean catch specimen, often don't fit. Instead of focusing on exceptional presentations – a hallmark of other healthcare professions – we try to standardize collection with expensive kits, complex instructions, and harder to read signs. What many patients hear, often enough, is "Pee in a cup."
If all patients are different, why should a "one fits all" approach to reflexive testing work? Perhaps, diagnostic algorithms that take into account the total testing process, including patient presentation and symptoms preceding the order, is the answer. Rules would account for age, gender, symptoms, medications, comorbidities, etc. This information could also guide the workup. It might even reduce unnecessary testing.
All of which still needs to be told to the physicians, somehow, to get "medical necessity." Don't get me started on billing.