Periodic colonoscopy. With nuisance complications.
Three days of prep, nothing but clear liquids since Sunday, a gallon of slime over 12 hours, and "Nope, not clean enough." I got a standby slot late in the day, bought another gallon of slime powder, mixed it in a drinking fountain, chugged it from a bummed Starbucks cup, and camped in a public restroom.
So, 2 gallons of slime in 24 hours, and I was deemed marginal but they'd try.
Nothing found. Come back in 5 years.