About 70 per cent of blood agency Héma-Québec's stock is in quarantine, due to concerns about small cracks found in the bags used to collect blood.
Despite the quarantine, the agency said there is no shortage of blood.
Laurent-Paul Ménard, director of external communications for Héma-Québec, said there was a problem with the equipment used to collect the blood.
Small leaks, or microcracks, were found in some bags.
The agency said the cracks could be from a manufacturing defect.
Ménard said the blood, some of which has already been distributed to hospitals, risks being exposed to the air. Air exposure could create favourable conditions for bacterial growth.
In a statement released by Héma-Québec on Thursday, the agency said tests are currently being carried out on the quarantined blood. Depending on the outcome of those tests, blood found to be safe will be recirculated.
The temporary quarantine was a preventive measure and Ménard said the agency is still able to respond to urgent needs.
At least five hospitals in Montreal have been affected by the quarantine. Some surgeries have been delayed at:
The Centre Hospitalier at the University of Montreal.
The McGill University Health Centre.
The Montreal Heart Insitute.
St. Mary's Hospital.
Santa Cabrini Hospital.
Emergency surgeries will still be performed and trauma centres will be able to respond to demands.
Radio-Canada reported that the situation has forced the cancellation of surgeries at the Chicoutimi Hospital and the Alma Hospital, both in the Saguenay-Lac-Saint-Jean region.
Ménard did not say how many other hospitals in Quebec could be affected.
Blood products currently available for transfusion are safe, according to Héma-Québec.
The agency also assured there is no risk to anyone who recently received a blood transfusion.