Patients could battle to get free scans and other diagnostic tests as public health services are forced to prioritise even more to stay within budget, Otago's chief medical officer says.

Richard Bunton says it is "crunch time" across the country - and in fact around the world - as costs balloon and health services scramble to find ways to relieve the pressure.

Public health services will be forced to take the next step in rationing, moving on from prioritising surgery to procedures used to diagnose patients' non-life- threatening conditions.

Mr Bunton, who is with the Otago District Health Board, predicted yesterday that within five to 10 years specialists would be allocating people points to show how urgently they needed scans and other procedures to diagnose their conditions , just as specialists allocated points now for surgery.

That would create an official waiting list for the diagnostic procedures which health services could actually afford to provide.

Many people would have to seek diagnostic procedures for non-life-threatening conditions in the private sector to actually get them done.

Mr Bunton, a heart surgeon who helped to create the nationwide surgery points system introduced in the mid-1990s, also works in the private sector. He said procedures to help to diagnose patients' conditions were increasingly high-tech and high-cost, making them a very important factor in the overall cost of health care.

MRI scan machines, for example, were expensive to buy and operate. Angiography, the injecting of an opaque substance into arteries to check for narrowing, was not cheap either.

Mr Bunton said increasing costs had forced New Zealand to acknowledge it could not afford to provide all health care to everyone, and health boards were no longer being topped up with money when they ran out of funding.

At the same time, modern technology was ramping up medical-sector inflation to two or three times the standard rate of inflation.

But the private health sector did not have capped funding and its income increased with patient numbers. The private sector also did not have the overheads public services needed to cater for emergencies at any time, he said.

His comments come amid debate about whether public health services should treat only emergency and urgent cases.

Beehive staff say Health Minister Pete Hodgson will deliver a frank speech on the Government's policy on surgery waiting lists at Victoria University today.