What is the difference between a smear test and an HPV test?
Smear test versus HPV DNA test: what each one measures, from what age and how often screening is done, and what an abnormal or positive result means.
A smear test examines cells taken from the cervix and detects a cellular change that is present now. An HPV DNA test looks for the high-risk types of human papillomavirus that can lead to cancer, whether or not any change has yet appeared in the cells. That is the practical difference between them: one answers how do the cells look at this moment?, the other answers is a virus that carries risk present?
What the smear (Pap) test measures
A small brush is used to take a sample of cells from the cervix. In the laboratory these cells are examined under a microscope for structurally abnormal (dysplastic) cells. Because it shows the cellular picture at that moment, a smear can be thought of as a snapshot.
What the HPV DNA test measures
The HPV DNA test looks in the same sample for the genetic material of high-risk HPV types. It is not concerned with how the cells look, but with whether a virus capable of causing cancer is present. Persistent high-risk HPV infection is the central risk factor in the development of cervical cancer.
The core differences
What it measures
- Smear: the structural change present in the cells now.
- HPV DNA: the presence of a high-risk HPV type.
Sensitivity
- Smear: varies, roughly between 30% and 78%.
- HPV DNA: around 96%.
Long-term reassurance
- Smear: more limited.
- HPV DNA: a negative result gives stronger and longer-lasting reassurance.
How it is used
- Smear: alone, or together with the HPV test (co-testing).
- HPV DNA: alone as primary screening, or as co-testing.
These figures come from current international screening guidelines (USPSTF, ASCCP, ACS) and can vary from person to person.
From what age, and how often
- 21-29 years: a smear (cytology) alone every 3 years. In this age group most HPV infections clear on their own, so HPV testing is not used in routine screening.
- 30-65 years: one of three options — an HPV DNA test alone every 5 years, co-testing (HPV plus smear) every 5 years, or a smear alone every 3 years.
- After 65: screening may be stopped if there have been enough negative results in the last 10 years (for example two consecutive negative HPV or co-tests, or three negative smears). Where there has been treatment for a high-grade cellular change in the past, screening continues for longer.
Some guidelines recommend starting at 25 with an HPV test; others recommend starting at 21 with a smear. The starting age and interval right for you are set by your doctor after your personal risk factors are considered.
What a result means
An abnormal smear or a positive HPV test does not mean cancer. What follows — a repeat test, colposcopy or further investigation — depends on age, previous screening history and how the tests read together. For that reason the interpretation and the next step must be decided by a doctor.
Frequently asked questions
Are the smear and HPV test done at the same time?
Over the age of 30 they can be done together (co-testing), but an HPV test alone or a smear alone are also screening options.
Is the HPV test painful?
The sample is taken in the same way as for a smear — from the cervix. It is usually a short procedure and not uncomfortable.
If HPV is positive, does that mean cancer?
No. Most HPV infections are cleared by the immune system over time. A positive result is a sign that closer follow-up is needed; it is not a diagnosis of cancer.
See also smear and HPV testing.