TORONTO - A veteran surgeon testified Tuesday that he never acted upon a patient's complaint of being sexually assaulted during an operation because he thought it would be impossible for such an incident to happen.

Dr. Robert Michael Brock, an orthopedic surgeon, said the elderly woman complained to him that she was fondled and kissed by anesthesiologist Dr. George Doodnaught.

Brock performed her knee replacement surgery while Doodnaught was the anesthesiologist at North York General Hospital in January 2010.

Brock said he was "completely taken aback" when the woman, 66, disclosed her allegation.

"I was trying to console the patient. It was such a bizarre statement," Brock told Crown attorney David Wright.

Brock said he never relayed her complaint to anyone "because I had no belief in the original event. I just didn't think it was possible.

"I believed it was purely as a result of the narcotics and there were many reasons but that is the major one," he told Justice David McCombs.

The woman is one of 21 patients alleging Doodnaught sexually assaulted them while they were consciously sedated during operations between February 2006 and 2010.

The women's identities are protected by a publication ban.

Doodnaught, 64, has pleaded not guilty to all charges.

With 35 years of experience performing inside the small crowded operating rooms at North York, Brock said he suggested to her that she was either hallucinating on the drugs or misinterpreting a doctor's legitimate touch.

Brock said that she might be mistaking the doctor's manipulation of her breasts in order to reapply or replace the monitoring ECG devices as fondling.

ECG "leads" are placed on the patient's chest and torso so that person's heart rate can be monitored during surgery, said Brock.

"It would not be uncommon for an anesthetist to move the breasts to replace or remove the leads during surgery," said Brock, who performs 150 knee replacements and other procedures each year.

In 2010, Brock reported the allegation to Dr. Stan Feinberg, the hospital's chief of surgery, after the hospital administration told personnel to co-operate with the police investigation.

The trial resumes Wednesday.