Check the Other Side
I’m a biomedical scientist, and my officemate was a medical doctor working on his PhD. He once did an appendectomy and cut into this person’s abdomen—only to find no appendix. He started freaking out. The support nurses in the room, however, started snickering at him because they knew right away what the problem really was.
Occasionally, they see someone with a rare genetic disorder where all their left-right asymmetries are reversed. This patient’s appendix was on the other side. Story credit: Reddit/SatanScotty