I was very careful and very lucky to have never been involved in a foreign body case. There was a case in which a sponge was left behind and the matter was quickly hushed up. The patient was told that a second surgery was necessary to tidy things up. Back in the day patients asked few questions.
The site really shows some eye-popping scenarios. The account of a nurse getting a TPN line mixed up could have had a really bad outcome. Luckily, the error was caught before serious damage ensued.