Researchers investigating the frequency of medical errors during surgical operations discovered that surgery tools are left inside about 1,500 patients every year. The study, conducted by examiners at Boston's Brigham and Women's Hospital and Harvard School of Public Health, analyzed insurance records from 800,000 operations performed in Massachusetts from 1985 to 2001. During that period, 61 pieces of surgical equipment were left in 54 patients.

From that data, researchers determined the national yearly estimate to be 1,500 cases. Most of the lost objects were sponges, but several cases included metal clamps and electrodes. One patient died from complications. Published in Thursday's edition of The New England Journal of Medicine, the study suggests that surgeons perform X-ray checks after operations are completed to ensure tools are not left inside the patient.