Health insurers are planning on refusing to pay -- or let their patients be billed -- for hospital errors. They claim that this is an effort to improve patient safety and reduce health-care costs.

Aetna, WellPoint, and other big insurers are moving to ban payments for any care resulting from serious errors, such as operating on the wrong limb or giving a patient incompatible blood. This follows the lead of the federal Medicare program, which soon will no longer pay the extra cost of treating bed sores, falls and several other preventable injuries and infections that occur while a patient is in a hospital.

Private insurers will first ban reimbursements for only the gravest mistakes. But it is likely only a matter of time before they also stop paying for some of the more common and less clear-cut problems, such as hospital-acquired catheter infections or blood poisoning.

Some hospitals are concerned that the new strategy could drive up medical costs as hospitals absorb or pass on the expense of introducing the safety and screening procedures needed to help avoid mistakes.