The latest snapshot of NSW hospitals reveals that Wollongong Hospital ED saw 18,588 patients from July to September 2019 - up six per cent on the same quarter last year.

Just over half (53.4 per cent) of patients left the ED within the state government's four-hour benchmark during the quarter according to the Bureau of Health Information figures, released on Wednesday.

That's down 6.3 percentage points on the figures for the same period in 2018 - and it is far lower than the current state average of 68.1 per cent.

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The figures also showed that four out of 10 patients suffering from a critical illness or in severe pain didn't start their treatment within the clinically recommended 10 minutes from July to September.

'Emergency' or T2 patients include those with severe chest pains, severe fractures or difficulty breathing.

Meantime over a third of 'urgent' or T3 patients - such as those bleeding heavily from cuts or with major fractures - did not begin treatment within the recommended 30 minutes.

Of all patients, just 70 per cent started treatment on time.

It took patients an average of three hours and 18 minutes to be treated and discharged from Wollongong Hospital; and an average of six-and-a-half hours to be treated and admitted to the hospital.

Executive Director Clinical Operations Margaret Martin said there'd been a continued surge in numbers of patients at Wollongong Hospital during the period.

A significant increase in T1 or resuscitation cases, as well as emergency and urgent presentations, had also meant more complex assessment and treatment has been required.

The increased demand had been felt across all Illawarra Shoalhaven Local Health District hospitals, which saw almost 3000 more patients than during the same period in 2018.

This was largely due to the longest flu season since the 2009 pandemic, she said.

"ED presentations were higher across the district than for the same period last year, with 42,225 presentations in the quarter, a 7.4 per cent increase," she said.

"In addition, there was an 8.8 per cent increase in the number of people who arrived at our hospital EDs by ambulance - 12,268, up from 11,275 for the same period last year."

Ms Martin said there was a number of initiatives underway to improve the delivery and timeliness of emergency department care.

These included a clinician-led review of patient access and flow within the ED and the recruitment of additional ED senior staff specialists to enable increased early assessment of patients.