By 5pm on Wednesday, more than 40,000 people had signed a petition urging the federal government to abandon its changes to the way it pays pathology providers under the Medicare Benefits Schedule.

But pathologists and medical researchers have cast doubt on claims the changes will result in a $30 cost for pap smears, pointing out the government is only proposing to cut payments to pathologists by $3.20 per pap smear – even if pathologists passed on the cuts in full.

A spokesman for Health Minister Sussan Ley said the government was not proposing to cut rebates, but rather wanted to cut "an inefficient payment – worth between $1.40 and $3.40 – that is paid direct to pathology corporations separate to the Medicare rebate".

On December 15, in its mid-year budget update, the federal government announced plans to cut bulk-billing incentive payments for pathology services, including pap smears, blood tests and urine tests, from July 1, 2016.

It says these changes - and changes to bulk billing for MRI scans and other imaging services – will save $650 million over four years.

The Royal College of Pathologists of Australasia has said the move would force patients to pay at least $30 for pap smears, as well as higher costs for urine and blood tests, because previous government cuts made it "very unlikely" laboratories would be able to absorb the added costs.

While the government disputes those figures, a social media backlash rapidly gathered pace from Tuesday night, after an article was published on women's site Mamamia about the three-week old pap smear announcement.

The government has said it will only cut payments to pathology providers, and not to GPs or to rebates for the services.

A Sydney pathologist, who asked not to be named, said: "There shouldn't be any outrage - the pathology companies will absorb it. And I'm a pathologist!"

But the Australian Medical Association said the changes would lead to pathology services passing increased medical costs to consumers.

"When they [the government] make these announcements, just like the co-payments, they don't talk to anyone," AMA president Brian Owler said. "They don't talk to pathologists, they don't talk to doctors, they just make these announcements and then they wonder why everyone gets upset."

Labor's health spokeswoman Catherine King said the cuts would have "a devastating impact on women's health".

"Labor is deeply concerned by reports these cuts could force women to pay more for crucial preventive health checks like pap smears that are essential for detecting life-threatening conditions like cervical cancer," she said.

"Every year, over 800 Australian women are diagnosed with cervical cancer, and around a third of those women are likely to die from the disease."

The government has previously announced it will phase out pap smears from 2017, in favour of human papillomavirus (HPV) testing.

The changes follow recommendations from the Medical Services Advisory Committee, which said the changes - together with the HPV vaccination program - would reduce the rate of cervical cancers by 15 per cent.

Under the renewed National Cervical Screening Program, women aged 25 to 74 years, both HPV vaccinated and unvaccinated, will be invited to undertake a test for HPV, the virus that can cause pre-cancerous abnormalities, every five years.

The process for testing for HPV is the same as for the pap smear, and the procedure will be covered by the Medicare Benefits Schedule.

- with AAP