Abnormal Pap Smear? Here’s What It Means (and What Comes Next)

If you have a cervix, you probably don’t think much about it — until it’s time for a Pap smear. A Pap is a routine test, and if the results are normal, you won’t have to think about it again for a few years. But what if you get a message from your healthcare provider that something didn’t look quite right? That can be a frightening experience. So it’s empowering to understand what those Pap results mean. 

We’ll walk you through an explanation of an abnormal Pap smear. This way you can be fully informed when it's time to have a conversation with your healthcare provider about what happens next.

What does a Pap smear look for?

A Pap smear is a test that looks for cancer and precancer of the cervix. It also looks for signs of HPV (human papillomavirus) infection — the most common cause of cervical cancer and precancer. 

The cervix is located at the lower part of the uterus. It functions like a tunnel between the uterus and vaginal canal. A healthcare provider can perform a Pap smear during a pelvic exam (although not every pelvic exam includes a Pap smear). During the exam, they use a small swab or brush to collect cells from the cervix. Then they check those cells for any changes that could lead to cervical cancer.

Cervical cancer usually develops slowly, over many years. If your immune system isn’t working well, it could happen faster. There are a series of precancerous changes that happen before cervical cancer begins. That’s where a Pap smear comes in. It looks for changes in cells before cancer starts. It can also check for HPV. 

Because these changes happen slowly, most people don’t need to do routine Pap smears very often. But it’s still an important test that can detect and prevent cervical cancer. Experts recommend a Pap smear for anyone with a cervix who is:

• Between 21 and 29 years old: every 3 years

• Between 30 and 65 years old: every 3 years, or every 5 years if done together with a test for HPV

After age 65, you don’t need a Pap smear if previous tests weren’t high risk.

You may need a test more often if your Pap smear shows changes from HPV or if you have a health condition that affects your immune system.

How reliable are the results of a Pap smear?

As a screening test, the Pap smear has been around for a long time. And the technology for collecting and examining the cells has improved over the years. But, like any test, it’s not perfect. Getting a Pap smear at the recommended intervals improves its ability to detect changes over time.

When someone has the earliest precancerous changes, a Pap smear is about 68% sensitive. This means that it will accurately detect those changes in 68% of people who truly have them. Pap smears are also around 75% specific for these early changes. This means that the test is normal in 75% of people who truly don’t have precancerous changes. When looking for more advanced precancerous changes, a Pap smear is 70% to 80% sensitive and 95% specific.

What does an abnormal Pap smear indicate?

In general terms, Pap smear results are classified as normal (negative), unclear (AS-CUS), or abnormal. HPV results are either positive (HPV is present) or negative (no HPV is present).

Abnormal results are broken down into these groups:

• AS-CUS: This stands for “atypical squamous cells of undetermined significance.” These are the cells that don’t quite look normal. But it’s not clear that they’re precancerous, either. An AS-CUS result usually means there’s an HPV infection, which is what is causing the cells to look slightly abnormal. This is why a test for HPV can help to clarify the results (more on this below).

• LSIL: This is a “low-grade squamous intraepithelial lesion.” That means the cells are mildly abnormal. Like AS-CUS, it’s usually caused by an HPV infection. Over time your body often clears the infection and the abnormal cells. But you’ll need follow-up testing to be sure.

• HSIL: This stands for “high-grade squamous intraepithelial lesion.” It means there are more advanced changes in the cervical cells. This requires additional tests and close follow-up to be sure it doesn’t become cancer.

• ASC-H: This stands for “atypical squamous cells, cannot exclude HSIL.” This result is like ASC-US in that it can’t be classified exactly. But in this case, there are changes that look more like precancer. ASC-H also needs close follow-up and additional tests. 

• AGC: This stands for “atypical glandular cells.” Glandular cells are found deeper inside the cervix and in the uterus. This result could also be a kind of precancer. It requires other types of tests and close follow-up. 

As you can see, any abnormal Pap smear result includes some uncertainty about two things:

1. What the abnormal result ultimately indicates (HPV infection, precancer, or cancer)

2. How your body will respond to the changes (and whether your immune system will clear the abnormal cells or not)

This is where additional testing comes in. It will help figure out why your cells are abnormal — and what the follow up plan is. 

Tests you may need after a Pap smear

Every person’s case is a little different. The additional testing you may need is based on several factors: 

• Your initial results, and what category they fall into

• Your age

• Any additional risk factors for cervical cancer

• Previous Pap smear results

Your healthcare provider will help you figure out what other tests you may need. Some of these tests may include: 

• HPV testing and typing: If you didn’t do an HPV test together with the Pap, your provider will probably order it if the Pap test is abnormal or unclear. This can show whether HPV is present and which specific types of HPV there are. Some types of HPV are more likely to cause cervical cancer than others. Your provider can do HPV testing with the same sample of cells that was originally taken for the Pap smear.

• Repeat testing: An abnormal Pap smear result may simply mean you need to repeat the test in 6 months or 1 year. This is to check to see if your body has cleared the abnormal cells. 

• Colposcopy: This test is like a more involved Pap smear. It gives your provider a closer look at your cervix. Your provider will perform another pelvic exam, but this time they’ll use a device that magnifies the cervix. If an area appears abnormal, they’ll take a small sample of tissue from the cervix. They can then send that sample to the lab for more complete information about the health of the cervix.

• Endometrial sampling: When there’s an AGC result, your provider will use a thin, flexible tube to take a sample of tissue from the lining of the uterus.

It might feel frustrating to have to go through more testing or wait for a more definitive answer. But this stepwise approach is intentional. Many abnormal Pap smears are the result of temporary changes in the cervix. So a measured and patient approach can save you from testing or treatment that you might not need. And it will give you more complete information if there are changes that require treatment to prevent cervical cancer.

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Written by:

Anne Jacobson, MD, MPH

Anne Jacobson, MD, MPH has been a board-certified family physician since 1999. She worked as a full-scope family physician (inpatient, outpatient, obstetrics, and office procedures) in the Cook County Ambulatory Health Network for 15 years.

Edited by:

Katie E. Golden, MD

Katie E. Golden, MD, is a board-certified emergency medicine physician and a medical editor at GoodRx.

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