Mercy Medical Center was cited for a lab mix-up that resulted in an incorrect diagnosis of breast cancer for a woman in her 30s, The New York Times reported Monday. The woman opted for a double mastectomy because of her family history and died of complications the day after her surgery last May.

The Health Department concluded that the hospital had taken proper corrective action after the mix-up but said it is investigating Mercy over the deaths of three other patients.

That probe, the Times said, was prompted by the complaints of one of its doctors that a physician's assistant had improperly inserted catheters, chest tubes and pacemakers into patients.

A spokeswoman for the department said it is unclear when the investigation will end.

The National Academy of Sciences estimates that as many as 98,000 people die each year as a result of medical errors.