What Do Your Pap Smear Results Mean?

A Pap smear can reveal the presence of suspicious cells on the cervix that need further testing or treatment, but learning about the results of your test can be very confusing. If your test is abnormal, your report may include a number of different findings. From "ASCUS" to "intraepithelial lesion" and more, what exactly do these results mean? And, based on the results, what may be the recommended next step?

What Is a Pap Smear?

A Pap smear, also called a Pap test, is a procedure to screen for cervical cancer or abnormal changes that might lead to cervical cancer without treatment. It involves collecting cells from the vagina and cervix—the lower, narrow end of the uterus that's at the top of the vagina. The Pap smear is usually done in conjunction with a pelvic exam. A primary HPV test is a test for high risk strains of HPV (cancer-causing strains) that can be done at the same time as a Pap smear, but may also be performed on a Pap smear sample after it has been sent to a lab.

Beginning at age 25, either a primary human papillomavirus (HPV) test, or a combination of an HPV test and Pap smear are recommended every 5 years until the age of 65. If primary HPV testing is not available, a Pap smear is recommended every 3 years. More frequent testing and/or further evaluation may be recommended if the test is abnormal.

These guidelines are for people who have an average risk of developing cervical cancer. For those who have an elevated risk, such as those who are taking immunosuppressive medications or have HIV, additional screening measures may be recommended. More frequent screening is also often recommended for those who have had abnormal results in the past.

HPV is a very common sexually transmitted disease that can lead to cervical cancer in some women. While there are many strains of HPV, only certain strains are linked to cervical cancer, and the primary HPV test is designed to look specifically for these strains.

Normal Pap Smear Results

If your Pap smear is read as normal, your doctor will also consider the results of your HPV test (or recommend that one be done on the same sample if it was not previously done).

If both your Pap smear test and HPV test are normal (and if you do not have a history of abnormal Pap smears/HPV tests in the past) you likely won't need any further testing or treatment until your next screening test is recommended (five years for HPV testing or cotesting).

Normal Pap But Positive HPV Test

If your Pap smear is normal but your HPV test is positive, your doctor will talk to you about possible recommendations. There are a few different reasons why this may occur. Most commonly, it means that an HPV infection is present but not causing any abnormalities in the cervical cells at the time. Most HPV infections clear without causing abnormalities or cancer. On the other hand, it could be that the Pap smear sample did not pick up an area of abnormal cells (false negative). Recommendations may vary depending on your age, your history of HPV testing in the past, and whether your test was positive for HPV 16 or 18. These may include earlier follow-up or proceeding with a colposcopy.

Abnormal Pap Smear Results

If abnormal or unusual cells were discovered during your Pap smear, you're said to have a positive result.

Here are some terms your doctor might use and what your next course of action might be:

Atypical Squamous Cells of Undetermined Significance

One abnormal result you may receive is called Atypical Squamous Cells of Undetermined Significance, or ASCUS. Squamous cells are thin and flat and grow on the surface of a healthy cervix.

In the case of ASCUS, the Pap smear reveals slightly abnormal squamous cells, but the changes don't clearly suggest that precancerous cells are present.

In fact, while an ASCUS Pap smear result may sound alarming, it's considered only mildly abnormal and is actually the most common abnormal Pap smear result you can receive. There may, in fact, be no immediate cervical cancer risk associated with your ASCUS Pap smear result.

The most common causes of ASCUS Pap smear results are noncancerous (benign) conditions, such as infections or inflammation. These conditions can cause cervical cells to appear abnormal. Eventually, however, most cells return to a normal appearance with time.

For some women, an ASCUS result is due to changes in the cervical cells caused by HPV infection. With the liquid-based Pap smear test, your doctor can reanalyze the sample to check for the presence of certain high-risk types of HPV virus known to promote the development of cancers like cervical cancer.

That being said, in most cases, these cervical changes do not progress to cervical cancer but do require further monitoring and possible treatment to prevent an increased risk of cervical cancer.

Squamous Intraepithelial Lesion

This term squamous intraepithelial lesion (SIL) indicates that the cells collected from the Pap smear may be precancerous. These changes may be reported as either low-grade squamous intraepithelial lesion (LSIL or LGSIL) or a high-grade intraepithelial lesion (HSIL or HGSIL).

LSIL

If the changes are low-grade (LSIL) it means the size, shape, and other characteristics of the cells suggest that if a precancerous lesion is present, it's likely to be years away from becoming cancer (if it does at all). These changes are most commonly caused by infection with an HPV virus, but the many of these infections resolve on their own. If you've had a Pap smear that shows LSIL, there's a moderate risk that you will go on to develop HSIL (below).

With a Pap smear showing LSIL, the first step is to look at the HPV Test (and to order one if not previously done). If the HPV Test is negative, a repeat HPV Test and Pap smear may be done in one year. If your HPV Test is positive, especially for HPV 16 or 18, a colposcopy (with or without biopsies) may be recommended.

Certainly, these recommendations will vary depending on your age, your history of abnormal tests in the past, your pregnancy status, and whether you have any risk factors such as immunosuppression.

HSIL

If the changes are high grade (HSIL), there's a greater chance that the lesion may develop into cancer much sooner.

Since a Pap smear alone cannot determine if precancerous cells are present, further testing is needed. This is true whether your HPV test is positive or negative.

Often times the next step is a colposcopy, with biopsies of any abnormal appearing regions. This can determine if cervical intraepithelial neoplasia (CIN)2, CIN3, or sometimes AIS (adenocarcinoma in situ) is present.

If instead, the risk of CIN3 or AIS is thought to be high, your doctor may recommend "expedited" treatment, that is, proceeding directly to treatment rather than performing a colposcopy and biopsies. Treatment options include those that remove (excise) tissue, such as a LEEP procedure or a cone biopsy (laser or cold knife conization), or those that ablate tissue (such as cryosurgery). In the US, excisional treatments are usually preferred.

Atypical Glandular Cells

Glandular cells produce mucus and grow in the opening of your cervix and within your uterus. Atypical glandular cells may appear to be abnormal, which raises a worry for the presence of precancer or cancer.

When atypical glandular cells are seen on a Pap smear, further testing is needed to determine the source of the abnormal cells and their significance. For non-pregnant women, a colposcopy along with biopsies (endocervical biopsy) is recommended whether or not an HPV test is positive. In addition, for women over the age of 35 or those under 35 who have risk factors for uterine cancer (endometrial cancer), an endometrial biopsy is also recommended.

Squamous Cell Cancer or Adenocarcinoma Cells

If your result reports squamous cell or adenocarcinoma are present it means the cells collected for the Pap smear appear so abnormal that the pathologist is almost certain a cancer is present.

"Squamous cell cancer" refers to cancers arising in the flat surface cells of the vagina or cervix. "Adenocarcinoma" refers to cancers arising in glandular cells. If such cells are found, your doctor will recommend a prompt evaluation and treatment. It's important to note that a Pap smear contains a collection of cells but does not say anything about the relationship of the cells to each other. For this reason, it's impossible to determine if the cancerous-appearing cells that are found are carcinoma in situ (non-invasive, and in theory, completely curable if removed), or invasive (and hence, truly cancer).

Follow-Up After an Abnormal Pap Smear

The recommended follow-up after an abnormal Pap smear depends on the findings, any treatment you receive, your age, your history of Pap smears and HPV testing in the past, and more. This usually includes more frequent screening for a period of time, either with HPV/Pap testing or colposcopy.

It's important to note that for people who have significantly abnormal Pap smears (eg. HSIL and up) and after the initial period of increased screening, screening (HPV testing or HPV testing plus a Pap smear) will be required every three years for a full 25 years. The reason for this is that the risk of cervical cancer with these findings persists for at least 25 years.

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Prevention

Even if you've had an abnormal Pap smear or HPV test, it's important to know that, in addition to careful follow-up, lifestyle measures may reduce your risk of developing cervical cancer. For example, while smoking does not cause cervical cancer, it appears to increase the chance that people who develop high-risk HPV infections (the cause of most cervical cancers) will go on to develop the disease.

In addition, HPV vaccination (Gardasil 9) is recommended for all women between the ages of 9 and 45 whether or not they have been sexually active. A Swedish study found that among women vaccinated under the age of 17, the incidence of cervical cancer was 88% lower than those who were not vaccinated. For those vaccinated later (between the ages of 17 and 30), the incidence was 53% lower.

A Word From Verywell

Detecting cervical cancer early with a Pap smear gives you a greater chance at a cure. It's better still when abnormal changes can be found (and treated) before they have an opportunity to progress to cervical cancer in the first place. Remain educated about your cervical health and keep up with your pap smears. Another tidbit is to remember not to have sex, douche, or use tampons or other vaginal hygiene products 48 hours prior to your Pap smear test, as these can give false results.