When you go for an operation, the biggest worry is probably waking up from the anaesthetic. But what if you got more than you bargained for? An average of two operations a week in Britain end with surgical instruments being sewn inside patients' bodies. In 2008, more than 700 NHS users were left harbouring forceps, scissors, swabs and pliers, according to one newspaper. Last June, ex-soldier Maureen Deeley finally had removed a swab left inside her during a 1996 operation. She had been, she said, "in agony for 14 years".

Probably not as much agony as 37-year-old Li Fu, who complained to his doctor about severe headaches. The cause of the pain was a 10cm-long blade which, following an armed robbery, had not been spotted by doctors and had remained embedded in his brain for the past four years. "The knife was almost intact when we removed it," said Luo Zhiwei, one of the surgeons who performed the operation last week.

Almost contemporaneously, French surgeons were removing a pair of 4in-long forceps from the stomach of a woman who had gone to hospital for a tummy tuck – and subsequently experienced terrible stomach pains. It was only after a piece of metal could be seen sticking through her skin that doctors realised something more serious was afoot.