PITTSBURGH (AP) _ The University of Pittsburgh Medical Center’s lung transplant program has been put on probation by the United Network for Organ Sharing, a nonprofit that oversees American transplants.

The group says UPMC too frequently took lungs intended for one donor and gave them to another after the first intended transplant patient was determined to not be suitable or able to receive it.

UPMC says the practice of using back up patients is approved by regional organ procurement groups and is meant to ensure the organs _ which are in high demand _ don’t go to waste.

But UNOS says the 14 times that occurred in 2013 and 2014 was “unusually high” and calls into question whether the lungs might have gone to needier patients.

UPMC can still conduct lung transplants but must notify patients of the probation.