The Royal Children's Hospital Melbourne is advising families to seek alternative care on Monday night as it faces "unprecedented demand" in its emergency department.
In a statement shortly after 5pm, the hospital said there were 90 patients in the ED and it anticipated some children with less serious conditions could be waiting more than 12 hours on Monday evening.
The hospital said it was experiencing "unprecedented demand with a high number of presentations of extremely unwell children", with both the volume of patients and the severity of their conditions contributing to the delays.
"We will always treat the most seriously ill children first which unfortunately means some patients with less serious conditions may experience longer wait times," a spokesperson said in a statement.
The Royal Children's is Australia's leading paediatric hospital and Victoria's designated major trauma centre for paediatrics.
The hospital said it was trying to get more staff on.
"Staff have volunteered to work extra shifts and we have put a call out to unrostered clinical staff to assist," the statement said.
"With extremely high levels of acuity of our already admitted inpatients, it is not safe to discharge patients to free up beds.
"We have flexed our inpatient wards where it is safe to do so."
It advised families to try Nurse on Call on 1300 60 60 24, the Victorian Virtual Emergency Department or online telehealth options.
Triple-0 should always be called during the event of a emergency.
'Nothing unique' about 'surge' in patients
The hospital's chief of medicine, Tom Connell, said the hospital was doing everything it could.
"We aren't understaffed — we're staffing as best as we can, recognising that there have been challenges like any health service throughout COVID," he said.
"People are staying back and doing a little bit extra to try to cope with this demand over the next few hours."
He said Monday's demand reflected a trend.
"I think we have seen increasing numbers throughout November and into early December presenting for care to our emergency department," he said.
"We know our figures over even pre-COVID are increased compared to similar time periods pre-pandemic — so we're definitely seeing more patients.
"There's nothing unique about today, but we just seem to have gotten a real surge in the number of patients presenting this afternoon."
Hospital CEO Bernadette McDonald said it could take days to reduce waiting times in the emergency department.
"We will be experiencing these challenges probably all through this week," she said.
She said some elective surgeries were delayed on Monday, and expected more to be postponed as increased demand continued.
"We're trying really hard not to do that because we do have patients who have been delayed previously due to COVID," she said.
"But we do need to meet our emergency demands — both surgery and medical."
Ambulance Victoria activated a code red for a few hours on Saturday morning when it was experiencing extreme demand, saying 140 staff had been furloughed due to COVID.
