WINNIPEG—Documents obtained by the Winnipeg Free Press show one Manitoba woman’s mastectomy may have been unnecessary and several other patients received incomplete diagnoses after their biopsies went missing.
The incidents occurred months before pathology officials said diagnostic errors were “extremely unlikely.”

Documents obtained through a Freedom of Information request reveal that health officials launched seven critical incident investigations into diagnostic errors between July, 2007 and March, 2008, including the probe into errors made by a veteran St. Boniface Hospital pathologist.
Critical incidents are defined as serious, unintended events suffered by a patient in a health care facility, and are investigated by an internal review committee.
In March, Diagnostic Services Manitoba CEO Jim Dalton denied there were any problems with the province’s pathology program and told the Free Press that diagnostic errors or botched tests were “extremely unlikely.”
Documents refute that—and show that multiple investigations into pathology errors were underway at the time.
In two separate incidents in July and November, 2007, groups of samples and specimens were lost, which prompted exhaustive searches of a pathology lab and various other health facilities.
As a result, several patients did not receive a complete diagnosis while others had to be retested.
Several other patients had to have a second biopsy after a piece of lab equipment malfunctioned in September, 2007. Some patients did not receive a complete evaluation as a result.
A mistake interpreting a breast tumour sample in July, 2007 led to one woman being misdiagnosed with aggressive breast cancer.
Subsequent reviews of the woman’s case by an Ontario laboratory and second pathologist found there was “no evidence of invasive cancer,” and that the woman’s mastectomy may have been unneeded.
The woman isn’t identified in the documents because of privacy concerns, but documents say the case will be reviewed by her physician.
Another patient did not receive appropriate antibiotics after a follow-up pathology report wasn’t sent to that patient’s physician last February. The mistake led to an extended hospital stay.
“If we found through one of these investigations that we thought there was an unusual event or unusual risk, we would make it public,” Dalton said last week. “But certainly the rate of these incidents is well within the norm I’d put that up against any laboratory in North America.”
Dalton said the pathology program is in excellent shape, and that these incidents involve a small number of specimens out of the millions that are processed each year.
Dalton couldn’t say how many patients may have received an incomplete diagnosis due to lost specimens, but said human error was responsible in the case of the woman who had a mastectomy.
“No errors are good, and we’re not trying to gloss these over and say they’re OK,” he said. “Most reports are timely, accurate, and I think the system works very well and people should have confidence in it.”