Cervical screening is a preventive health test designed to identify high-risk human papillomavirus, or HPV, and associated cervical-cell abnormalities that could eventually develop into cervical cancer. It is sometimes still called a "smear test", although modern programmes use HPV testing as the primary screening method. The key conceptual point is that cervical screening is not primarily a test for established cancer. Instead, it identifies people at increased risk and, where necessary, detects cellular changes early enough for them to be monitored or treated before invasive cancer develops.
In England, people with a cervix are routinely offered cervical screening between the ages of 25 and 64, with invitations generally issued every five years under the current programme, although the interval and follow-up pathway can vary according to HPV results and individual circumstances. Current NHS England guidance describes a more personalised programme in which HPV-negative results indicate very low future cervical-cancer risk and allow longer screening intervals for many participants, while HPV-positive results can lead to closer surveillance. Eligibility is based on having a cervix rather than simply on sex or gender identity, so trans men and non-binary people with a cervix can also require screening.
During a routine screening appointment, a healthcare professional uses a speculum to gently visualise the cervix and obtains a small sample of cervical cells with a soft brush. The sample is sent to a laboratory where it is tested for high-risk HPV types. If high-risk HPV is not detected, the risk of developing cervical cancer is very low and no further cellular examination of that sample is generally necessary. If high-risk HPV is detected, the sample can be examined for abnormal cell changes. This sequence makes HPV testing the primary screening step while cytological assessment provides additional information when HPV is present.
Screening results can broadly indicate that no high-risk HPV was detected, that high-risk HPV was detected without abnormal cell changes, or that high-risk HPV was detected together with abnormal cell changes. An HPV-positive result does not mean that someone has cervical cancer. HPV is common, and the immune system often clears it. Depending on the result and screening history, the person may be invited for repeat screening after an interval or referred for colposcopy, which allows a specialist to examine the cervix more closely and, when necessary, take a biopsy. The purpose of this pathway is to distinguish transient infection from persistent HPV-associated cellular abnormalities that warrant further investigation.
Cervical screening is different from a diagnostic examination for symptoms. Someone experiencing unusual vaginal bleeding, bleeding after sex, unusual discharge, pelvic pain or other concerning symptoms should contact a healthcare professional rather than waiting for their next routine screening appointment. Screening is performed on people without symptoms to identify increased future risk, whereas diagnostic assessment investigates an existing symptom or clinical abnormality. Screening also does not test for every gynaecological cancer; it is specifically designed around cervical disease and should not be regarded as a general examination for ovarian, uterine, vaginal or vulval cancer.
Cervical screening has limitations. No screening test is perfect, so high-risk HPV or abnormal cells can occasionally be missed, producing a false-negative result, while a small proportion of people can receive an abnormal result when clinically significant disease is absent. There is also a small possibility that abnormal changes develop between screening appointments. Screening can therefore reduce risk substantially without eliminating it completely. An abnormal screening result also does not automatically mean cancer, because many abnormal cellular changes are precancerous or transient and can be monitored or treated before invasive malignancy occurs.
The terminology surrounding cervical screening has evolved with improvements in understanding HPV and cervical carcinogenesis. Earlier screening programmes relied principally on cytological examination of cells, commonly known as the Pap smear or smear test. Modern primary HPV screening reflects evidence that persistent high-risk HPV is the fundamental cause of almost all cervical cancers and that identifying the virus can stratify future risk effectively. Cytology remains important when HPV is detected because the laboratory can examine the same sample for abnormal cells. This approach shifts screening from simply identifying abnormal cells towards identifying the underlying infection that creates the principal risk.
The practical purpose of cervical screening is therefore prevention through risk identification, surveillance and timely treatment rather than simply finding existing cancer. If persistent high-risk HPV produces precancerous cellular changes, treatment can remove or destroy those abnormal areas before they become invasive. The programme works alongside HPV vaccination rather than replacing it: vaccination reduces the probability of infection with important oncogenic HPV types, while screening provides ongoing protection because vaccines do not cover every cancer-causing type. Regular participation remains relevant even for people who have been vaccinated or who consider themselves at low risk.
