Phillip Hughes remained in a critical condition in hospital on Wednesday afternoon, nearly 24 hours after being struck in the head by a bouncer during a Sheffield Shield match at the SCG.

At 2.05pm, Australia's team doctor Peter Brukner spoke to the media outside St Vincent's Hospital in Sydney, where Hughes had undergone surgery on Tuesday to relieve pressure on his brain.

"Phillip's condition is unchanged and he remains critical," Brukner said. "If there are any further developments we will let you know immediately."

Earlier on Wednesday, Cricket Australia had elected to abandon the full round of Sheffield Shield matches following the injury suffered by Hughes on day one of the match between New South Wales and South Australia.

That game was abandoned as soon as Hughes was taken to St Vincent's Hospital, and after deliberations between CA and the Australian Cricketers Association, it was decided that it would not be fair or appropriate to continue the matches between Victoria and Western Australia in Melbourne or Tasmania and Queensland in Brisbane.

"We've spoken to players and the ACA, and given how players across the country are feeling right now, it's just not the day to be playing cricket and we understand that," CA's team performance manager Pat Howard said. "We are continuing to offer all players and match officials counselling and support at this difficult time.

Road and air ambulances arrive at the SCG Getty Images

"Phillip Hughes continues to receive the best possible medical care. The thoughts of his teammates and the wider cricket community are with Phillip and his family and friends."

One point will be given to each team for the abandoned matches, under the terms of CA's revised playing conditions for the Shield this summer. ACA chief executive Alistair Nicholson supported the decision.

"The ACA supports Cricket Australia's decision to abandon the remaining matches in this round of the Sheffield Shield," he said. "We note that the advice of experts and the thoughts of the players were given strong consideration in this decision.

"We agree that given the unique and very serious nature of this situation, players and officials are best placed surrounded by family and friends, supporting one another and sending their best wishes Phillip's way.

"The ACA is continuing to provide counselling support for players and their families, and extends this support to any former players who may be affected by the events in Sydney."

The NSW Ambulance service released a statement on Wednesday describing the timeline of events according to their records. Hughes was struck about 2.23pm and was taken to hospital just under an hour later.

"The initial triple zero call was received by NSW Ambulance at 2.37pm, arriving at the patient at 2.44pm where two paramedics provided support to the doctor on site treating the patient'" a NSW ambulance spokesperson said. "Another four paramedics in two other ambulance vehicles arrived at 3.02pm.

"The NSW Ambulance helicopter, with a specialist doctor and paramedic medical crew on board, was tasked to respond at 2.50pm, landing on the SCG at 3.05pm. The patient was assessed and stabilised by the medical team before it was decided that road transfer to St Vincent's hospital was the most appropriate course of action given the patient's injuries.

"The thoughts of staff and paramedics from NSW Ambulance are with the patient and their family at this time."