Investigators probing unnecessary mastectomies at a Windsor hospital said Wednesday they have "significant concerns" about the work of a pathologist whose diagnostic reports preceded the operations.

A three-person investigative team, led by former Ontario chief coroner Dr. Barry McLellan, reviewed surgical and pathology practices at three Windsor-area hospitals, including Hotel-Dieu Grace Hospital, where two women had mastectomies despite the fact they did not have cancer.

After a review of more than 6,200 pathology cases of Dr. Olive Williams, the investigators said they "expressed concerns about potential adverse clinical consequences of certain diagnoses made by Dr. Williams and had significant concerns with the quality of a subset of her reports."

Specifically, investigators had moderate or major disagreement with the original diagnoses in 221 of the cases. A further probe determined the disagreement over 45 of those cases "may have clinical significance that might need further investigation, treatment or patient follow-up." The team worked with the three hospitals to determine the appropriate responses to these cases, and determined that eight of the 45 needed additional investigation and/or treatment.

Despite the disagreements, the report deemed Williams' error rate to be within an acceptable range.

The investigators recommended that Williams, who has been under suspension from the hospital since January, undergo a "clinical competency assessment" by the College of Physicians and Surgeons of Ontario should she wish to return to work in the province.

During a press conference in Windsor on Wednesday, McLellan could not say what may have led to Williams' errors. An internal report written by health authorities suggested cataracts may have played a role in possible errors.

"We certainly did not find any evidence to support any physical or medical condition contributing to any increase in rate because we didn't see that increase in rate over time," McLellan said.

The team also largely cleared Dr. Barbara Heartwell, the surgeon who performed the operations, saying that after reviewing 128 of her surgical cases, she "generally performed safe surgery and provided safe care."

The report expressed concern that Heartwell may not be keeping up-to-date on new patient management and surgical techniques, but said that has likely not had a significant impact on the quality of her work.

The team recommended that the hospital reconsider the restrictions it placed on her practice when it reinstated her surgical privileges earlier this year. It also recommended she participate in quality and professional development initiatives.

The probe was ordered in March by Ontario Health Minister Deb Matthews after two women said they had unnecessary mastectomies.

Laurie Johnston has filed a $2.2 million lawsuit against Heartwell, Williams and both the Hotel-Dieu Grace and Leamington District Memorial Hospital after having a mastectomy last November before learning she did not have cancer.

Janice Laporte had a breast mistakenly removed by Heartwell in September 2001. She sued in 2002 but a confidentiality clause prevents Laporte from discussing the outcome.

The investigation also included Windsor Regional Hospital and Leamington District Memorial Hospital, but the team said it found the "major issues of public concern" centred around the surgery and pathology practices at Hotel-Dieu Grace.

The report makes 19 recommendations in total, including that the province's health ministry develop a provincial quality assurance system for pathology and that it implements that system by March 31, 2011.

It also recommended the Hotel-Dieu Grace improve its pathology reporting processes and its professional development systems for pathologists, and that hospital staff be trained in reporting errors.

The team also found a "concerning lack of respect" between the Hotel-Dieu Grace's top doctors, senior management and the board of directors and called on them to work together to foster a more supportive work environment.

The team also made a number of quality and safety recommendations for all three hospitals.

Following the report's release, Matthews appointed Malcolm Maxwell, CEO of Grand River Hospital in Kitchener, as a facilitator to oversee the implementation of the recommendations.

"I know this process has been difficult for some patients and their families and I hope that Dr. McLellan's report will provide them with the answers they have been looking for," Matthews said in a statement Wednesday.

"Today, the investigators have said that Windsor and Essex County residents can have confidence in the quality of care their hospitals are providing. I share that confidence."

With files from The Canadian Press