300% Mortality Rate

Gordon describes what he calls Liston's most famous case in his book, as quoted verbatim below.

Amputated the leg in under $2\frac{1}{2}$ minutes (the patient died afterwards in the ward from hospital gangrene; they usually did in those pre-Listerian days). He amputated in addition the fingers of his young assistant (who died afterwards in the ward from hospital gangrene). He also slashed through the coat tails of a distinguished surgical spectator, who was so terrified that the knife had pierced his vitals he fainted from fright (and was later discovered to have died from shock).

— Richard Gordon(https://en.wikipedia.org/wiki/Robert_Liston#cite_note-RichardGordon15-32)

This episode has since been dubbed as the only known surgery in history with a 300 percent mortality rate.