I asked my girlfriend to sit on my lap. When she took a shit on my lap I wasn't mad though, since yes, it's two words, but they're pretty similar so confusion is inevitable.
It costs nothing to say "lab testing" instead of "in vitro". Literally the same number of syllables, zero loss of precision, and immediately understandable to a wider audience.
In vitro is a consice term, useful to me in my profession.