Bomb experts raced to a hospital after a patient arrived with an artillery shell in his bottom.
The explosives team were scrambled to Gloucestershire Royal Hospital as doctors feared that the anti-tank round could be about to blow.
The unnamed patient told medics that he "slipped and fell" on the projectile taken from his private collection of military items.
It was later identified as a World War II shell that had been fired from anti-tank guns.
A source told The Sun newspaper: "The guy said he found the shell when he was having a clear out of his stuff.
"He said he put it on the floor then he slipped and fell on it — and it went up his a***.
"He was in a considerable amount of pain. I think he collected military memorabilia."