The peak body for emergency room doctors said the Clarence Street attack could have been avoided if governments had heeded their calls to fix the crisis in hospital emergency departments.

Simon Judkins, president of the Australian College of Emergency Medicine, said he was not surprised to learn that the man accused of the murderous rampage had spent hours waiting in an emergency room at Blacktown Hospital before absconding the health system.

Dr Simon Judkins said the Sydney stabbing "highlights to us the failures that we're seeing in the system". Credit:Jason South

He said doctors in ERs across the nation were having to make decisions every day about which patients were the "least risky" to release to the public, as state hospitals heaved under the demand for psychiatric services and seriously unwell patients "fall through the cracks".

"We're seeing patients across the system, and it's not just NSW, spending three, four or five days in emergency departments," he said.