When I was in my late-40's, I woke up one morning with a bad stomach/abdominal ache. I thought it was something I ate, but the ache got worse and worse, to the point of excruciating pain. My wife had left for the morning, so I said that's it and drove myself to the ER. Well, they admitted me, the doc checked me over and over and then resigned himself to saying all he could think it was was a had stomach flu, or such.
Then, he say's wait a second and had me lie flat on my back with my feet dangling over the table. Oddly, he then began to smack the bottom of my heels with his fist. At that point he said, "we're admitting you." It was determined that I had a perforated appendix and had surgery right then and there. It was the strangest experience. Glad he caught it. Otherwise, obviously, would have been life-threatening.
https://en.wikipedia.org/wiki/Heel_tap_sign