The chief of pediatric surgery at McMaster Children's Hospital says the deaths of two children following tonsil and adenoid surgeries at his hospital are "tragic" and "very rare."

"We are deeply saddened by their deaths and offer our sincere condolences to their families," Dr. Devin Peterson said in a video posted online Friday — two days after the Hamilton hospital announced the children's deaths and plans for an external review.

One child died the day after their surgery and the other died nine days after having the procedure, a statement on Hamilton Health Sciences' website said, noting the hospital had paused all but emergency pediatric tonsil and adenoid surgeries as of Tuesday.

The surgeries will not resume until the external review is completed, Peterson said.

"McMaster Children's Hospital is a leading pediatric centre and we take this responsibility very seriously," he said.

According to the Canadian Society of Otolaryngology, about five per cent of patients bleed after surgery and may need to return to hospital as a result.

"Tonsillectomy is considered major surgery. The main risk is bleeding, which can be serious," the society's website says.

"Most bleeds occur seven to 10 days after surgery, but rarely, a bleed can occur as late as 17 days after surgery."

McMaster Children's Hospital performed 584 pediatric tonsil and/or adenoid surgeries last year and 5.8 per cent of patients returned to the emergency department after being discharged, Hamilton Health Sciences' website said.

On Friday, the Hamilton Spectator reported that another child who had tonsil and adenoid surgery at the hospital in May began vomiting blood the morning after the procedure.

The paper said the eight-year-old girl was released with hours of having the surgery. She became critically ill and ended up in the intensive care unit, her grandfather Dr. Stephen List told the Spectator. She survived but has not yet fully recovered, List said.

In an emailed response to The Canadian Press, a spokesperson for Hamilton Health Sciences said patient care decisions such as when they can be discharged after surgery "are based on the clinical expertise of their care team, standard clinical guidelines, patient appropriateness and safety, and with the consent of the family."

Clinical practice guidelines recommend that patients younger than three years or those with severe obstructive sleep apnea be kept overnight for monitoring after having tonsil and/or adenoid surgery, Lillian Badzioch, manager of issues management and risk communications, said in the email.

But for most other children, it's a day procedure, she said.

"Most children, three years of age and older that have tonsil and adenoid surgery are discharged home the same day as per clinical practice guidelines and after they’ve met the criteria for safe discharge," Badzioch said.

This report by The Canadian Press was first published June 7, 2024.