Screening & Gynecologic Cancer

Abnormal Pap Smear Results Explained: ASC-US, LSIL, HSIL and What Comes Next

By the Find Her Doctor editorial team · Updated November 1, 2026 · 6 min read

An abnormal Pap smear means some cells on your cervix look different from normal. It almost never means cancer. Most abnormal results come from HPV, they're mild, and many clear up on their own. What happens next (a repeat test, a colposcopy or treatment) depends on the exact result, your HPV status, your age and your past history.

If you're reading this because a portal notification just popped up with a word like "ASC-US" and no explanation, you're in good company. That message usually lands before anyone from the office calls, and it's one of the most common reasons people search this topic late at night. Take a breath. Here's how to read it.

How to read the result on your portal

Labs report Pap results using the Bethesda system. It sorts cells by type (squamous or glandular) and by how abnormal they look. Low-grade changes are common and usually harmless. High-grade changes are less common and more likely to need treatment.

Since 2019, U.S. clinicians follow ASCCP risk-based guidelines. Instead of reacting to one result, your clinician estimates your risk of serious precancer (called CIN 3) using:

  • Your current Pap and HPV results
  • Your previous results
  • Any past treatment
  • Your age and pregnancy status

That's why your friend with the "same" result may have gotten different advice. Your history changes the math.

Abnormal Pap results at a glance

Result What it means Typical next step (age 25+)
NILM Negative, normal Routine screening
ASC-US Atypical cells, unclear meaning Depends on HPV: negative, repeat in 3 years; positive, colposcopy (or 1-year retest if low risk)
LSIL Low-grade changes, usually HPV Usually colposcopy; repeat testing may be an option if HPV-negative or low risk
ASC-H Atypical cells, can't rule out high grade Colposcopy
HSIL High-grade changes Colposcopy, or treatment such as LEEP in some adults
AGC Atypical glandular cells Colposcopy plus other tests; endometrial biopsy if 35+ or at risk

These are general patterns. Your clinician applies the full guideline to your history.

ASC-US: the most common "abnormal"

ASC-US stands for atypical squamous cells of undetermined significance. The cells look a little off, but not clearly abnormal. HPV is one cause; so are inflammation, infection and low estrogen after menopause.

Most labs run an HPV test on the same sample, so you often don't need to come back in just to find out:

  • HPV negative: Your risk is low. You can usually go back to routine screening in 3 years.
  • HPV positive: Most people are referred for colposcopy. If you had a negative HPV test in the past 5 years, a repeat test in 1 year may be enough.

LSIL: low-grade, usually HPV

LSIL means low-grade squamous intraepithelial lesion. It reflects HPV causing mild changes, and it often goes away on its own within a year or two, especially in younger people.

For adults 25 and older, colposcopy is still usually recommended. If your HPV test was negative, or you have a recent run of normal results, a repeat test in a year may be an option. Ask which one applies to you.

ASC-H: "can't rule out high grade"

ASC-H means atypical squamous cells, cannot exclude HSIL. The lab sees changes that might be high grade. Colposcopy is recommended no matter what the HPV result says.

HSIL: high-grade, but still not cancer

HSIL means high-grade squamous intraepithelial lesion. These changes are more likely to turn into cancer over time if they aren't treated. HSIL is still precancer, not cancer, and it's very treatable.

Next steps usually include colposcopy with biopsy. For non-pregnant adults 25 and older with HSIL and a positive HPV 16 result, ASCCP guidelines allow going straight to treatment with a LEEP procedure. This is called "expedited treatment." If you're planning future pregnancies, say so; it's part of the conversation about whether to biopsy first or treat right away.

AGC: the one that needs a wider look

AGC means atypical glandular cells. Glandular cells line the cervical canal and the uterus, so the workup is broader: colposcopy, sampling of the cervical canal, and usually an endometrial biopsy if you're 35 or older or have risk factors for uterine cancer. AGC is less common, and it's the one result where you shouldn't let the follow-up slide.

What if you're under 25 or pregnant?

Ages 21 to 24

HPV is extremely common at this age and usually clears. For ASC-US or LSIL, most people repeat the Pap in 1 year instead of having a colposcopy. ASC-H and HSIL still need colposcopy.

During pregnancy

Colposcopy is safe in pregnancy, but biopsies are limited and treatment is usually delayed until after delivery unless cancer is suspected. Precancer generally doesn't harm the pregnancy. Your OB will usually fold the follow-up into your prenatal visits.

What causes an abnormal Pap smear?

Nearly all significant abnormal results come from persistent high-risk HPV. A few things make it harder for your body to clear the virus:

  • Smoking
  • A weakened immune system, including HIV
  • Long-term immunosuppressive medicines

Inflammation, infection and low estrogen can cause mild "atypical" findings, but they don't cause precancer. And no, stress doesn't cause abnormal Pap results. Yes, everyone asks.

A common worry is what an HPV-related result says about a partner or a relationship. The honest answer: HPV can stay quiet for years, so a new result usually can't tell you when or from whom you got it.

How long does it take abnormal cells to become cancer?

For most people, the path from HPV infection to cervical cancer is slow. It often takes 10 years or more for persistent high-risk HPV to cause high-grade precancer and then invasive cancer. Many low-grade changes never progress at all.

That slow timeline is good news:

  • You usually have time to follow up and treat precancer before it becomes cancer.
  • A wait of a few weeks for a colposcopy appointment is generally safe.
  • Missing follow-up for years, not weeks, is what raises risk.

It also explains why guidelines often say "repeat in a year" for low-risk results rather than treating right away. Treating every mild change would mean many unneeded procedures, and some can affect future pregnancies.

Your to-do list after an abnormal result

  • Get your exact result in writing. Ask for the Pap category and the HPV result (and HPV 16/18 typing, if it was done). Save it; your next clinician will want it.
  • Ask, "What's my next step, and by when?" Put the date in your phone the same day.
  • Quit smoking if you smoke. It makes HPV harder to clear.
  • Ask about the HPV vaccine. It's routinely recommended through age 26, and adults 27 to 45 can discuss it. Your gynecologist can tell you whether it makes sense for you.
  • Use condoms. They lower, but don't eliminate, HPV spread.
  • Keep every follow-up. Missed follow-up is one of the main reasons precancer goes untreated.

If you're uninsured in New York, the state's Cancer Services Program offers free cervical cancer screening and diagnostic follow-up to people who qualify, so cost doesn't have to be the reason you skip a colposcopy. Medicaid and the Essential Plan also cover screening and follow-up.

When to see a doctor

Call your provider if:

  • You got an abnormal result and don't know your next step
  • You were told to repeat a test and the date has passed
  • You have bleeding after sex, between periods or after menopause
  • You have pelvic pain or unusual discharge that doesn't go away

If a biopsy shows cancer, or you have repeated high-grade or glandular abnormalities, you may be referred to a gynecologic oncologist. To find a gynecologist close to home or work, use our provider search or browse by borough, like gynecologists in Brooklyn.

Frequently asked questions

Does an abnormal Pap smear mean I have cancer?

Almost never. Most abnormal Pap results reflect HPV-related cell changes that are mild and often go away on their own. Cancer is found in only a small fraction of abnormal results.

What does ASC-US mean on a Pap smear?

ASC-US means atypical squamous cells of undetermined significance. The cells look slightly unusual but not clearly abnormal. Next steps depend on your HPV result.

Is LSIL serious?

LSIL is a low-grade change usually caused by HPV. It often clears on its own, but most adults 25 and older are referred for colposcopy or close follow-up depending on HPV status and history.

What happens if my Pap shows HSIL?

HSIL means high-grade changes that are more likely to become cancer if untreated. You will usually need a colposcopy with biopsy, and some adults may be offered treatment such as LEEP right away.

Can stress or a yeast infection cause an abnormal Pap?

Inflammation or infection can sometimes make cells harder to read, but true abnormal results like LSIL or HSIL are caused by HPV, not stress.

Sources

  • ASCCP — 2019 Risk-Based Management Consensus Guidelines for Abnormal Cervical Cancer Screening Tests
  • ACOG — Abnormal Cervical Cancer Screening Test Results (FAQ)
  • National Cancer Institute — Understanding Cervical Changes
  • American Cancer Society — Cervical Cancer Screening Test Results

This article is for general education and is not medical advice. It does not replace an evaluation by a licensed clinician who knows your history. If you think you have a medical emergency, call 911.