RALEIGH, N.C. — A state report obtained by WRAL reveals new information on a major medical mix-up that involves two Duke University Health System-affiliated hospitals, used hydraulic fluid and nearly 4,000 patients.

The report from the North Carolina Department of Health and Human Services' Division of Facility Services said that Duke Health Raleigh Hospital let an elevator repair company put used hydraulic fluid in old detergent containers. When they were left in the parking lot last September, the hospital ordered them removed.

Employees called the company on the container labels, Cardinal Health. When the barrels were redistributed, the state report said the hospitals accepted them, even though they were not properly sealed.

According to the report, the hospitals, Durham Regional Hospital and Duke Health Raleigh Hospital, cleaned surgical tools in the hydraulic fluid for weeks, even though staff members repeatedly complained that the tools came out oily.

Wake Forest University Baptist Medical Center in Winston-Salem received the same contaminated batch from Cardinal Health, but on Dec. 13, employees realized that something was wrong with its detergent when surgical equipment came out of a washer feeling greasy.

Workers halted the cleaning and checked the barrels, which were supposed to contain a clear, amber liquid. Instead, they contained a darker liquid with a greasy texture. The hospital then notified Cardinal Health.

According to the state report, it is not clear, what, if any, action Cardinal Health took because the hospitals in Durham did not discover a problem for two more weeks.

A spokesman for Wake Forest said workers caught the mistake immediately, so no patients underwent surgery with instruments washed in hydraulic fluid.

Cardinal Health told WRAL Thursday that it did not have anything to investigate at Wake Forest University Baptist Medical Center in Winston-Salem because the hospital threw out the liquid thinking it had expired.

Jeff Molter, a spokesman for Duke University Health System, said Duke's cleaning fluid is a very dark color, closer to that of the hydraulic fluid, than the cleanser that Wake Forest uses, and that is why it was not detected earlier.

Cardinal Health also said it had no idea the liquid was hydraulic fluid until Duke Health called the company on Dec. 30.