The research team suggested that more X-ray checks should be performed right after those operations where such errors are most likely to occur in order to ensure that no tool is left lodged inside the patient’s body.

Wands similar to supermarket bar-code readers might be developed eventually to detect missing equipment in patients’ bodies.

Dr. Sidney Wolfe, Health Research Director of the public-interest lobby group Public Citizen, said the real number of lost instruments may be even higher because hospitals are not obliged to report such mistakes to public agencies.

Wolfe said he felt these mistakes should be reported for the sake of protecting patients.

“If something is done to a patient that seriously risks his health, then the patient has a right to take legal action against the doctor,” he said. “It’s a malpractice on part of the doctor.”

Others said the mistake of leaving surgical tools inside patients is so rare—occurring about once in every 20,000 operations—that figuring out how to prevent them could be difficult.

Lori Bartholomew, research director at the Physician Insurers Association of America, said it could be hard to curb the number of such occurrences due to the nature of surgical operations.  

“It’s going to be difficult to make much more improvement, because some of the risk factors are things that are hard to control,” she said.