The health watchdog has been forced to take action against a hospital trust in East Anglia which performed a surgery on the wrong patient.
Monitor says that within a month, Cambridge University Hospitals NHS Foundation Trust performed four botched surgeries at Addenbrooke's Hospital.
They included leaving instruments inside two patients and performing surgery on the wrong person.
Surgeons also operated on the wrong part of the body of another patient. The trust says it's determined to improve.