#ThingsWeDoForNoReason: You're admitting a pt with no medical hx & a CC of watery stools & abdominal pain for 2 days. The ED has given fluids, and you wonder what admission tests you should order to figure out the etiology of the diarrhea. Which of these tests should you NOT get?

The test to avoid here is a Stool O&P! Though this is commonly included in our admission orders for a pt with suspected infectious diarrhea, most cases of acute diarrhea (24 hrs-14 days) are not due to parasitic infections - they're due to viral illness

The stool O&P also has a low sensitivity for Giardia and cryptosporidium, which are the most common parasitic causes of diarrhea in the US.

This isn't to say never order this test, especially if something in the history or labs leads you towards a parasitic etiology like a high eosinophil count, recent travel to an endemic area, or if your patient is immunocompromised.

This thread was inspired by an article in April's issue of The Journal of Hospital Medicine by Golfeyz et al: https://pubmed.ncbi.nlm.nih.gov/33734981/