In short
A cervical screening report has two halves: what the cells looked like, and whether high-risk HPV was found. NILM, ASC-US, LSIL, HSIL and an HPV-positive line each lead somewhere different.
Emergency if: Go to emergency care now for heavy vaginal bleeding that soaks through a pad within an hour or keeps returning, especially with dizziness, fainting, breathlessness or a racing heart, or for severe pelvic pain with fever. Blood loss at that rate is treated as an emergency in its own right, whatever the cause turns out to be.
On this page
01
Is my report about cells, the virus, or both?
Look for two separate results. Cytology, the Pap smear, reports what the cells brushed from the cervix looked like under a microscope, in words such as NILM, ASC-US, LSIL or HSIL. The HPV test reports whether DNA from a high-risk type of human papillomavirus was present, usually as detected or not detected. The National Cancer Institute describes the Pap test as collecting cervical cells to check for changes caused by HPV, and the HPV test as checking cells for infection with the high-risk types that can cause cervical cancer. A cotest is both, run on one sample.
Which of the two you were given depends on your programme and your laboratory, not on how worried anyone is about you. If your report carries only the Bethesda words, it is cytology. If it says high-risk HPV detected or not detected, and perhaps names type 16 or 18 on its own line, it is an HPV test. Many reports now carry both. Reading the wrong half is the commonest reason a normal report feels frightening: a positive HPV line sitting underneath the word normal is a common combination, and it has a settled, unhurried answer.
The direction of travel is towards testing for the virus first. On 4 December 2025 the American Cancer Society updated its guideline so that average-risk women and individuals with a cervix begin screening at age 25 and have primary HPV testing every five years through age 65. The World Health Organization recommends a high-performance test every five to ten years starting at age 30, and every three to five years from age 25 for women living with HIV. Our cervical cancer guide covers the disease itself; this story is only about reading the report in your hand.
02
NILM, an inflammatory smear and unsatisfactory — is that abnormal?
NILM means negative. It stands for negative for intraepithelial lesion or malignancy, and the National Cancer Institute's plain description of a normal result is that no abnormal cervical cells were found. It is the result most people get. If your report says NILM and the HPV line says not detected, and you have no symptoms, there is nothing to do before the next routine screen your programme offers. Symptoms run on a separate track: bleeding after sex, bleeding between periods or any bleeding after the menopause needs to be examined whatever the screening report said, because screening is built for people who have none of those. The word negative is doing real work here: it is the finding, not a hedge or a provisional note.
A line about inflammation, or about reactive cellular changes, describes how the slide looked — cells responding to infection, irritation or the thinning of tissue after menopause. It sits beside the category rather than replacing it, and among the cytology categories, the ones that trigger further action in the risk-based management guidelines begin at ASC-US. A note that endocervical or transformation-zone cells were absent is also not an abnormal result: for a person aged 30 or over with NILM cytology and no HPV result, those guidelines prefer an HPV test, and repeating cytology in three years is acceptable.
Unsatisfactory is a different thing altogether. It means the laboratory could not read the sample, because there were too few cells or because blood or mucus hid them. It is not a result, and the standard advice is to repeat the test in two to four months. Where atrophy or a specific infection was obscuring the slide, treating that first before the repeat is accepted. One exception matters: if the same sample showed high-risk HPV of type 16 or 18, direct referral for colposcopy is recommended rather than another smear.
03
ASC-US: why did the lab add an HPV test by itself?
ASC-US means atypical squamous cells of undetermined significance: cells that look slightly odd, with no way to tell from their appearance alone whether HPV is behind it. The National Cancer Institute calls it the most common abnormal Pap finding. Because the appearance decides nothing on its own, the laboratory runs a reflex HPV test on the sample already in the tube. That is a triage step rather than an escalation, and it is why an HPV line sometimes appears on a report you never asked for one on.
The virus result then splits ASC-US in two, and the gap between the halves is wide. In the risk data behind the 2019 ASCCP risk-based management guidelines, ASC-US with high-risk HPV present carries an immediate risk of finding CIN 3 or worse of about 4.2 percent. That sits just above the 4 percent immediate risk these guidelines set as the threshold for referral, so colposcopy is recommended. ASC-US with no high-risk HPV, in someone whose earlier screening history is unknown, carries an estimated five-year risk of about 0.40 percent and a return in three years.
Two practical points follow. Reflex testing needs cells left over in the sample, which is one reason a clinician-collected cervical specimen is preferred over a self-collected vaginal one. And where the HPV test is negative in someone past the menopause, thinning of the tissue is a common explanation for the odd-looking cells; the National Cancer Institute notes that an oestrogen cream may be prescribed to see whether the cell changes were caused by low hormone levels.
04
LSIL, HSIL and ASC-H: which one means colposcopy?
HSIL and ASC-H both mean colposcopy, and so does LSIL in most circumstances. HSIL, high-grade squamous intraepithelial lesion, describes moderately or severely abnormal cervical cells that could become cancer. ASC-H means the cells may be a high-grade lesion but the slide cannot settle it. AGC, atypical glandular cells, also leads to colposcopy; the National Cancer Institute describes it as a possible sign of a more serious problem higher up inside the uterus, so the assessment usually looks beyond the cervix as well.
The numbers behind those words differ enormously from each other, which is why they are not one category. In the data used for the 2019 ASCCP guidelines, HPV-positive HSIL cytology carried an immediate risk of CIN 3 or worse of 49 percent, and of CIN 2 or worse of 77 percent. ASC-H with high-risk HPV carried an immediate CIN 3 or worse risk of 26 percent; without HPV it was 3.4 percent, yet colposcopy is still recommended for every ASC-H, because the immediate cancer risk stays disproportionately high compared with the CIN 3 risk. Where the estimated risk runs higher still, treatment without a preceding biopsy becomes an option discussed alongside colposcopy rather than after it.
LSIL means low-grade changes usually caused by an HPV infection, and it sits far lower on that ladder. HPV-positive LSIL is above the colposcopy threshold; HPV-negative LSIL falls below it. Colposcopy itself is a magnified look at the cervix in a clinic room with a biopsy of anything that looks abnormal, not an operation. If you are pregnant or think you might be, say so when you book, because it affects what is done at the appointment. When the referral came from a low-grade result, the chance of CIN 3 or worse being found is in the region of one in twenty, so most people referred from an ASC-US or LSIL smear leave without a high-grade diagnosis.
05
HPV positive but Pap normal — does that mean cancer?
No. It means a very common virus was found and your cells currently look normal. The World Health Organization's position is that in most cases the immune system clears the virus naturally. Even when it does not, the National Cancer Institute's estimate is that it takes five to ten years for HPV-infected cervical cells to develop into precancers, and about twenty years to develop into cancer. A positive virus test on a normal smear is the earliest possible warning in a slow process, which is exactly what a screening test is built to produce. It is also not a statement about anybody's behaviour. The test reports the virus that is present now; it cannot say when it was acquired or from whom, and on the timescales above a result today says nothing about last month or about a partner.
What follows is usually a repeat rather than a procedure. In the risk data behind the 2019 ASCCP guidelines, high-risk HPV with NILM cytology carried an immediate risk of CIN 3 or worse of 2.1 percent, below the 4 percent threshold at which colposcopy is recommended, so repeat testing in one year with an HPV-based test is the recommendation. The National Cancer Institute's patient page puts the same thing in ordinary words: you may be advised to return for a repeat HPV test or HPV and Pap cotest in one or three years.
The genotype is the exception, and the next section covers it. One other thing is worth knowing if you tested yourself. The ASCCP practice advisory updated in October 2025 states that because a self-collected specimen is vaginal and the cervix is not sampled directly, a patient whose self-collected specimen is HPV positive will need a speculum examination by a clinician. That is not a sign the first test failed; it is the step that lets the laboratory look at cervical cells before anyone decides about colposcopy.
06
HPV 16 and 18 versus other high-risk types
The National Cancer Institute lists twelve high-risk HPV types, and two of them are handled differently from the rest. HPV 16 and 18 cause around 76 percent of cervical cancers, according to the World Health Organization, and the 2019 ASCCP guidelines state that HPV 16 or 18 infections carry the highest risk for CIN 3 and occult cancer, so additional evaluation such as colposcopy with biopsy is necessary even when the cytology result is negative. Many laboratories therefore report 16 and 18 on their own lines, with the other types pooled.
In practice that means colposcopy is recommended for HPV 16-positive NILM and for HPV 18-positive NILM, while the same NILM cytology with another high-risk type is managed by repeating the test in a year. The reasoning for HPV 18 is worth seeing, because it shows the thresholds are not applied mechanically: its measured immediate risk of CIN 3 or worse was 3.0 percent, below the usual colposcopy threshold, but its immediate cancer risk was disproportionately high at 0.2 percent, suggesting lesions that are harder to see or quicker to progress.
If your report names a type such as 31, 45, 52 or 58, that is extended genotyping, which several approved assays now offer. It does not mean a different disease, and there is no ranking to memorise below 16 and 18. What it can change, where local protocols use it, is how soon you are asked back. If your report simply says high-risk HPV detected with no type at all, that is equally normal: pooled reporting is what some approved tests are designed to give.
07
When can I go back to routine screening, and how often?
Follow the schedule of the programme that tested you, because the intervals genuinely differ between countries and there is no single worldwide answer. The American Cancer Society's December 2025 update starts average-risk screening at 25 with primary HPV testing every five years through 65; where primary HPV testing is not available, it accepts cotesting with an HPV test and cytology every five years, or cytology alone every three years. The World Health Organization recommends a high-performance test every five to ten years from age 30 for the general population.
The US Preventive Services Task Force's standing final recommendation still offers three options between 30 and 65 — cytology every three years, high-risk HPV testing every five years, or cotesting every five years — with cytology alone every three years from 21 to 29, and it recommends against screening under 21. Its proposed update, issued as a draft in December 2024 and still described as a draft in the ASCCP's October 2025 advisory, would make HPV primary screening every five years the preferred strategy from 30 and would include patient-collected samples.
Self-collection carries its own interval, which is easy to miss. The American Cancer Society's update makes clinician-collected cervical specimens preferred and self-collected vaginal specimens acceptable, but where a self-collected specimen is HPV negative it advises repeating in three years rather than five. The same update also revised when to stop: average-risk people may exit screening after negative primary HPV tests or negative cotests at ages 60 and 65, or, where those are unavailable, after three consecutive negative cytology tests with the last at 65.
08
If I have had the HPV vaccine, do I still need this?
Yes. The vaccines prequalified by the World Health Organization protect against HPV 16 and 18, which cause around 76 percent of cervical cancers — a large majority, but not all of them. They also work best before any exposure, which is why the WHO recommends vaccination for girls aged 9 to 14, ideally before sexual activity begins. Someone vaccinated later in life may already have met one of the covered types, and no vaccine removes an infection that is already established.
The WHO makes the screening point directly: precancers rarely cause symptoms, which is why regular cervical cancer screening is important even if you have been vaccinated against HPV. None of the schedules described above — the American Cancer Society's, the WHO's or the US Task Force's — sets out a separate, lighter timetable for vaccinated people. If your programme has told you otherwise, that instruction is the one to follow, but it is not what these guidelines currently say.
The practical reading is that the two halves do different jobs. Vaccination lowers your chance of ever having an abnormal result; screening finds what is left. If you were vaccinated and your HPV test still comes back positive, it is most often one of the high-risk types the vaccine does not cover, and it is managed in exactly the same way as anyone else's — by genotype, by what the cells look like, and by the interval your programme sets.
Symptoms that need attention whatever the report says
Routine — see a doctor
An abnormal result letter, a request to repeat an unsatisfactory sample in two to four months, or a colposcopy appointment: book it and keep it. A wait of a few weeks for the appointment itself is expected and is not dangerous; an appointment that never arrives is the real risk, so if the date in your letter passes with nothing booked, chase it, and say if the result was HSIL, ASC-H or AGC. A normal report with an inflammation note needs nothing extra before your next routine screen.
Same-day — call promptly
See a doctor the same day for bleeding after sex, bleeding between periods, any vaginal bleeding after the menopause, or a foul-smelling discharge with persistent pelvic, back or leg pain. The WHO lists these among the symptoms of cervical cancer. They need an examination even if a smear was recently normal, because screening is designed for people without symptoms and does not rule out disease in someone who has them.
Emergency — act now
Go to emergency care now for heavy vaginal bleeding that soaks through a pad within an hour or keeps returning, especially with dizziness, fainting, breathlessness or a racing heart, or for severe pelvic pain with fever. Blood loss at that rate is treated as an emergency in its own right, whatever the cause turns out to be.
Sources
- National Cancer Institute — understanding HPV and Pap test resultscancer.gov
- American Cancer Society cervical cancer screening guideline update, 4 December 2025pressroom.cancer.org
- ASCCP practice advisory: self-collection for cervical cancer screening, updated October 2025asccp.org
- 2019 ASCCP risk-based management consensus guidelinesportal.asccp.org
- US Preventive Services Task Force — cervical cancer screeninguspreventiveservicestaskforce.org
- World Health Organization — cervical cancer fact sheetwho.int
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