In medical school you learn that you should keep a weather eye for horses, not zebras (unless you live in Africa, possibly). The question is: How do you catch a zebra when one unexpectedly but inevitably shows up?
Zebra trying to hide, pretending to be a urinary tract infection.
Luckily, you do exactly what you usually do. When on the savannah, you shoot everything. What kind of wall trophies you get depends on whether you bring a gun or a camera. If there was a zebra there, even if it tried to hide, you'll have a zebra on the wall when you get home. When in the coal mine that is the ER, or the peat bog of general practice, you exclude the dangerous and the common and then you start excluding the less common (or refer for that purpose). The trick is to not fall for the obvious, common and dangerous diagnosis, and to remember to ask yourself how you account for the unexpected finding that doesn't fit.
So, why this sudden elaboration? Well, we just spotted a zebra, and not just any zebra, but a purple spotted zebra.
Wish us luck.