HPV triage and HPV primary screening both involve testing the sample of cells collected during the cervical screening test for high-risk HPV as well as examining the cells under a microscope (cytology). The order in which the HPV testing and cytology is done is where they differ.
With HPV triage, cytology is done first. Then HPV testing is done on any samples that come back with a cytology result of borderline or low grade cell changes (dyskaryosis). If no high-risk HPV infection is found during this test, the risk of the abnormalities turning into cancer is very low so the women will be returned to normal screening routine.
With HPV primary screening, the high-risk HPV test is done first and only if a high-risk HPV infection is found will cytology be done. If the results of the cytology are abnormal, at that point the woman will be referred to colposcopy, if they are normal she will be retested in 12 months.
HPV triage is currently used in both England and Northern Ireland in addition to cytology as part of the NHS screening programme. HPV primary screening will now replace the current cervical screening test across England.