A third of self-collected vaginal swabs for HPV DNA have not been processed, largely because the woman wasn’t eligible or the wrong kind of swab was used, cervical screening specialists say.

Of the 6234 self-collected swabs received over more than three years by the VCS Pathology — the first lab approved to process self-collected samples — some 2166 were rejected, they say.

More than half of these were refused because the person had not been overdue for screening, a key eligibility criterion for self-collection, according to a letter published on Monday in the Medical Journal of Australia.

The second most common reason for rejection (17%) was because the swab was either inappropriate or mishandled, say Associate Professor Julia Brotherton, Professor Marion Saville and Professor David Hawkes from the Australian Centre for the Prevention of Cervical Cancer (formerly the VCS Foundation).