Articles / Cervical screening: Is self-collection reliable?
Cervical cancer incidence and mortality rates have halved since the national screening program was introduced in 1991 — but about one quarter of eligible women are still not being screened.
To help rectify this, the option to self-collect a vaginal sample was extended to all women in July 2022 and has been widely taken up: 27% of all screening tests were done this way in the fourth quarter of 2023, compared to just 1% before the expansion. Increased uptake has been highest in the Northern Territory, very remote areas, women aged 70 to 74, and in those who are most disadvantaged.
The federal government says self-collected samples are equally accurate for detecting HPV as those collected from the cervix by a clinician.
However, 61% of more than 1800 GPs who participated in a Healthed survey in April said they believe self-collection is less reliable for detecting clinically significant abnormalities than a sample collected by a nurse or doctor
Furthermore, many GPs are choosy with self-collection, with the survey finding 27% only offered it to patients who are reluctant or refuse collection by a nurse or doctor, 15% only to patients who ask for it, and 6% not at all.
Experts say several misconceptions have persisted. Here are some facts they say it’s important to know as the government aims to eliminate cervical cancer by 2035.
The misconception that self-collected tests are less reliable may stem from the time the cervical screening test was first introduced when processing technologies were less sensitive than what we use today, says Professor Marion Saville, AM, Executive Director at the Australian Centre for the Prevention of Cervical Cancer.
Now, though, a large body of evidence demonstrates that self-collection is just as sensitive for detecting HPV and pre-cancerous abnormalities, provided a PCR based assay is used – which is a regulatory requirement for all tests performed under the National Cervical Screening Program, Professor Saville says.
There is one caveat, however.
The patient must collect the sample well for it to be as reliable as a physician-collected sample, says Professor Annabelle Farnsworth, AM – a specialist gynaecological histopathologist and cytopathologist and the Medical Director at Douglass Hanly Moir Pathology, who has been involved in a significant amount of research examining cervical screening.
At approximately 1.5%, the rate of unsatisfactory tests is significantly higher in self-collected samples, compared to approximately 0.4% for those collected by a doctor, Professor Farnsworth says.
“And that’s just because people don’t know how to do it. And it’s probably always going to stay relatively high.”
Her ultimate opinion?
“A good physician-collected sample into liquid is the perfect test. If people don’t want to have that, then [self-collection] is a really good alternative.”
However the team at the Australian Centre for the Prevention of Cervical Cancer say “the guidelines are clear that self-collection is just as accurate, and should be offered as a choice to all people,” not just those who aren’t keen on a physician-collected sample.
It’s also important that patients who self-collect are aware that they’ll need to return for liquid-based cytology if some types of HPV are detected, they add, noting that this occurs in about 6% of samples overall.
Getting a good sample
Professor Saville says patients need to insert the swab into their vagina and rotate it for at least 10 seconds.
She recommends explaining the process and assisting patients to collect the sample if needed, noting a vaginal sample taken with a self-collection swab would still be called a self-collected test on the pathology request form.
It’s also helpful to give patients printed instructions like those from the pathology labs or the Department of Health and Aged Care, says women’s health GP Dr Rebecca South, the clinical lead at Inner West Women’s Health in Sydney.
She suggests using a mirror to help patients better understand their anatomy if needed.
“I often encourage the person to watch where I’m taking the sample from or for them to collect the sample while I show them where to take it from.”
Patients should take the sample at the clinic rather than at home, and Professor Farnsworth stresses it must be collected using the red-topped FLOQ swab.
You can reassure patients that the swab doesn’t need to reach the cervix, Professor Saville says.
“Whether it is taken as a low, mid or high vaginal swab, it will still be an accurate test,” she says.
“This is because an active HPV infection doesn’t just sit on the cervix, it sheds into the vagina, meaning that using highly sensitive PCR technology, we can pick up the presence of viral DNA just as well from a vaginal sample as from a cervical sample.”
She adds that safety controls on HPV lab tests ensure that samples taken incorrectly, or affected by contaminants, are reported as ‘unsatisfactory’ rather than negative.
“Contaminants can include things like microbial infection, or lubricant, and may inhibit the PCR reaction and therefore the ability of an assay to detect HPV,” she explains.
“Therefore, if HPV is not detected, you can be confident that this is a true result from a representative sample, and if a patient has not taken the sample at all and returned the swab, this will simply give an invalid result.”
About one in four GPs who commented in Healthed’s survey were concerned about missing the opportunity to conduct a comprehensive pelvic examination.
However, this is no longer recommended in asymptomatic patients, according to Professor Saville and Dr South.
“Whilst this has previously been considered best practice, the reality is that there is no evidence to support the use of this in the context of routine cervical screening in an asymptomatic patient,” Professor Saville says.
Dr South agrees. “A pelvic examination on an asymptomatic person would be considered unnecessary and invasive and may in fact deter people from presenting for STI screening or cervical screening,” she says.
She does, however, stress the need to ask if the patient has any symptoms that could indicate the need for an internal exam, such as pain, abnormal bleeding, dyspareunia, or changes in discharge.
Vulvas are often neglected, she adds, and it’s important to assess them if indicated.
“I see so many people with advanced vulval pathology and they are literally in tears with gratitude when somebody looks at their vulva. I definitely do diagnose lichen sclerosis and even vulval cancer or vulval dysplasia in women who’ve had long-standing symptoms and haven’t been examined.”
Professor Farnsworth believes self-collection is a great option for reluctant screeners, noting this was the primary reason for introducing it.
“I hear a lot of stories from GPs and gynaecologists of someone who just didn’t want to test, but when you say you can have a self-collect, they’re quite happy to have it. That’s really what we want, because otherwise those people wouldn’t be having a test at all.”
Dr South says most people want to be involved in health screening but apprehension about an invasive test can seem to outweigh the benefits, and it’s “incredibly satisfying” to offer under-screened people an alternative that may be more acceptable. You can even offer this option during an unrelated consultation, she adds.
To explain the choice to patients, Dr South keeps a red-top swab, a plastic speculum and a cervix sampler brush in a drawer and shows patients the different collection options on a simple diagram of female cross-sectional anatomy.
Removing the need for a speculum examination, which remains the largest barrier to cervical screening participation, opens the program to many patients who may not have previously participated or have been putting off their test – which is particularly important given over 70% of cervical cancer cases in Australia occur in people who have never been screened or are overdue, Professor Saville says.
“We have lots of evidence demonstrating just how acceptable self-collection is for patients, particularly those who are under-screened,” she says.
Professor Farnsworth says patients should be reassured that they won’t be disadvantaged by self-collection.
Patients should also be informed that a practitioner-collected sample will be necessary if the test was unsatisfactory or positive for oncogenic HPV other than types 16 or 18, or a colposcopy if oncogenic HPV types 16 or 18 are detected.
Professor Saville says all people eligible for cervical screening should be given the choice of self-collection. Dr South agrees, noting some patients – such as those used to speculum examinations – may prefer you to collect a cervical sample.
Dr South also recommends checking patients’ screening status using the National Cancer Screening Register. This is now much more accessible, eliminates the need to rely on self-reporting, and helps stop patients from slipping under the radar.
“I think it is really good practice to prompt yourself to check the screening register before you call the patient in for their consult. It literally takes a second if the portals are open.”
You could also have someone in the practice run an audit and pop recall reminders in patient files, she says.
Importantly, self-collection is not suitable in patients who are symptomatic, although labs still sometimes get samples taken under these circumstances, Professor Farnsworth says.
“If someone’s symptomatic, then they do need a proper sample,” she says. “And the person needs to know they’re now no longer in the screening program. They’re being investigated for something.”
Nor is it appropriate for patients who require a co-test for any other reason, such as following a total hysterectomy with a history of high-grade squamous intraepithelial lesion.[1]
While self-collection is currently not recommended for Test of Cure surveillance, that’s set to change in updated clinical guidelines due out later this year, according to the Australian Centre for the Prevention of Cervical Cancer.
A national Government-funded campaign promoting cervical screening and the self-collection option is commencing in September, which will likely drive increased patient demand for self-collection.
Professor Saville suggests GPs who haven’t done so already contact their laboratories to ensure they have the correct swabs and handling instructions for self-collected samples and to review the latest evidence and clinical guidelines.
Encouragingly, a subsequent Healthed survey held on 28 May found a dramatic change in GPs perceptions of self-collection following this lecture by clinical microbiologist and infectious diseases physician Dr Nomvuyo Mothobi. After hearing Dr Mothobi’s talk, only 22% of GPs believed self-collected tests were less reliable, compared to 61% six weeks earlier. Significantly more GPs planned to offer self-collection to all their patients or all those who they think are capable of doing it properly. The results bode well for Australia’s goals to eliminate cervical cancer over the next decade.
The Australian Centre for the Prevention of Cervical Cancer has more information on self-collection, plus CPD modules, printable resources, and webinars.
The NCSP website has information for health providers, including cervical screening education modules.
Editor’s note: This is a slightly amended version of the article first published on 30 May 2024.
Reference:
1. ACPCC | Self-collection
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