Consumers are often told to "shop around" to save money, but for privately insured patients, calculating and comparing the out-of-pocket costs for surgeries can be "perplexing and sometimes impossible".
Ahead of a Senate committee delivering a report this week on the value of private health insurance, consumer group Choice is calling on surgeons and health funds to increase transparency and publish the average prices for common surgeries.
It conducted a mystery shop of 60 surgeons' offices around Australia and found more than a third - 22 - refused to provide information about fees, not even a ballpark figure.
Ease of access to information has become critical, with a report released earlier this year on the huge variations in surgeon fees triggering calls for patients to "shop around".
"With the average gap payment for knee surgery varying from $397 for South Australian patients to a staggering $2600 for ACT patients, consumers deserve to know how much they will have to fork out," Choice's Erin Turner said.
In its mystery shop, Choice researchers informed the 60 receptionists that they had private health insurance and were fully covered for the procedure. They inquired about a knee replacement, a cataract surgery and a tonsil removal.
While it was easy to get a quote for a consultation, 22 wouldn't provide further help, with a small fraction even declining to make an appointment without a fax from a GP.
The rest - 38 of them - said there would either be a gap or no extra cost. Of this group, eight provided a rough, ballpark figure, and 30 gave more detailed answers.
In relation to surgeons, higher fees do not necessarily mean better outcomes and quality of services. Often, the reverse is true.
"Patients in need of surgery are vulnerable and might be in pain, it's difficult for them to shop around and bargain with a doctor who soon holds their life in their hands," Ms Turner said.
"That's why we need a better system that protects patients getting surgery in the private system."
Earlier this year, a joint Medibank and Royal Australian College of Surgeons (RACS) report revealed the huge variations in fees and out-of-pocket costs for common operations - out-of-pocket costs for a radical prostatectomy ranged from $2800 to $10,700.
RACS president John Batten agreed the vast disparity was an issue, but said Choice's methodology of speaking to receptionists was problematic.
"The results don't surprise me because patients often ring up with misguided information and the receptionists are not geared or knowledgeable enough to know what is going on," he said.
He advised patients to speak to their health fund, which should be able to provide a list of surgeons with whom they have gap-related agreements.
"The college is in favour of transparency and fees being available to patients and GPs," he said.
"The college is not in favour of excessive fees at all; manifestly excessive fees are unethical and inappropriate and the patient shouldn't be exploited."
Rachel David, chief executive of peak body Private Healthcare Australia, said its research showed out-of-pocket costs for medical specialist services was becoming a significant consumer issue.
She said that, for services that attract a gap, charges were rising at 4 per cent a year, well above inflation.
"The issue of consumer transparency of medical out-of-pocket costs must be addressed as this sector is out of step with the level of disclosure required in the rest of the economy, including financial services," she said.
"It is a key factor reducing consumer confidence in the private health sector."
Ms David said the industry supported the use of online medical directory services to provide information to consumers and their GPs about the location and qualifications of medical specialists as well as the likely cost of treatment.
"We believe this should be done on a national basis, to give patients the option of travelling to find more cost-effective options," she said.
"We also believe the federal government and its agencies like the ACCC, in conjunction with the medical specialist colleges, need to explore sanctions against health professionals who fail to provide patients with a reasonable quote for treatment in advance, and who are found to be charging excessive fees."