MONTREAL - A surgeon blamed this week for 684 questionable colon scans at a west-end hospital has a history of professional infractions dating back several years.

Health officials announced Wednesday that the Lakeshore General Hospital patients must return for re-tests because their initial colonoscopies were "incomplete."

Officials refused to identify the doctor in question, but multiple media reports say his name is Gilles Bourdon, who has since resigned from the hospital.

The Quebec College of Physicians suspended Bourdon for two months in 2009 for other irregularities and he’s also being sued for $400,000 by the daughter of a patient who died under his care.

The colonoscopy scans, conducted between 2009 and this year, involve the insertion of a camera into the colon to detect lesions, inflammation, bleeding or cancer.

Officials say parts of patients'’ colons weren't scanned the first time around and that tests initially showed no abnormalities when in fact their colons did have problems. Authorities admit the errors could have fatal consequences.

"Colon cancer is the second deadliest cancer, which is why we are worried and do not want to take any chances," gastroenterologist Dr. Nadeem Ahmed told reporters this week.

The Quebec College of Physicians had previously reprimanded Bourdon for negligence.

One of his patients, Ivan Todorov, 83, died in February 2010.

A published report last year said Bourdon operated on a colon tumour but that Todorov's cancer continued to spread to other parts of his body.

It was only after Todorov died that his family learned of blood tests that indicated the continued presence of cancer. His daughter has filed a lawsuit.

In 2009, the college cited Bourdon for the 2003 death of a patient who had had a kidney removed. The college said Bourdon failed to take proper notes of the operation.

The college said the lax note-taking "poses unnecessary risks to patients" given that other health-care professionals are unable to track patients' medical history.

Bourdon was also found to have improperly logged the case of a patient whose gall bladder he removed in May 2004.

He misinterpreted test results and didn't read nurses' notes, leading to serious complications for the patient, including an irregular heartbeat.

Bourdon has been cited over the years for a total of 494 neglected patient files, including 409 related to operations he has performed.