A new barcode system replacing the program that led to a Nova Scotia woman receiving an unnecessary mastectomy will cost the province about $450,000.

The Capital District Health Authority confessed on Monday it made mistakes in two separate instances, both involving cancer patients.

A woman in her 60s had a breast removed when the process was unnecessary and the other patient, who needed surgery, was not scheduled for the procedure until after the mistake was caught.

In a second separate case, tissue samples were switched before the pathology analysis. One patient had an unnecessary diagnostic biopsy and the other patient never got the followup they needed.

The mistakes were later detected in laboratories.

Chris Power, the president and CEO of the Capital District Health Authority, said it was a combination of human and system error that led to the mistakes.

The Halifax-area health authority uses an oversight system that compares processed tissue from before and after a surgery to ensure they are the same.

There is a barcode system in place for their blood labs, but not for testing breast tissue.

Power said they are already in the process of bringing in a new barcode system, expected to be up and running by the end of this year, to track surgical samples.

It will cost $450,000, including the cost of implementation and training.

Canadian Blood Services has been using bar coding to track its donations from donor to recipient since 2009. They said it's as simple as scanning the identification number given to each donation.

Atlantic Canada director Michelle Rogerson said it gives her organization peace of mind.

"A manual process is very arduous. It’s more susceptible to human error," she said.

The president of the Canadian Association of Pathologists agrees.

Dr. Martin Trotter said his organization strongly supports the use of tracking systems, including bar code systems, as a quality assurance measure to reduce errors.

With files from the Canadian Press