Consult the medical resource doctors trust

UpToDate is one of the most respected medical information resources in the world, used by more than 600,000 doctors and thousands of patients to find answers to medical questions.

  • Content written by a faculty of over 5,100 physicians from leading medical institutions
  • Unbiased: free of advertising or pharmaceutical funding
  • Evidence-based treatment recommendations
  • Continuously updated to incorporate new medical findings

Patient information: Follow-up of low-grade abnormal Pap tests (Beyond the Basics)

INTRODUCTION

The cervix and vagina are lined by cells called squamous cells (picture 1). Atypical squamous cells (ASC) is the name given to squamous cells on a Pap test (also called a Pap smear or cervical cytology) that do not have a normal appearance but are not clearly precancerous. Low-grade squamous intraepithelial lesions (LSIL) on a Pap test are cells that appear slightly abnormal.

Cervical cancer screening is recommended starting at age 21 years (table 1). Women who have ASC or LSIL on a Pap test require further testing because some women with these findings have a precancerous lesion of the cervix.

This topic discusses the management of women with ASC and LSIL. The management of women with high-grade squamous intraepithelial lesions (HSIL) and atypical glandular cells (AGC) are discussed in a separate topic. (See "Patient information: Follow-up of high-grade abnormal Pap tests (Beyond the Basics)".)

ATYPICAL SQUAMOUS CELLS (ASC)

The ASC designation is subdivided into "atypical cells of undetermined significance" (ASC-US) and ASC-H, in which atypical cells cannot exclude a high-grade squamous intraepithelial lesion. A squamous intraepithelial lesion can be low-grade (low risk of developing into cervical cancer) or high-grade (precancerous cells with a moderate to high risk of developing into cervical cancer). The risk of a high-grade precancerous lesion in women with ASC-US is as high as 18 percent and for those with ASC-H, the risk is as high as 35 percent [1,2].

Cervical cancer screening is recommended starting at age 21 years (table 1).

Atypical squamous cells of undetermined significance (ASC-US) — ASC-US Pap tests are managed differently in women ages 21 to 24 than in those ages 25 and older.

There are two options for women with an ASC-US Pap test who are ages 25 or older:

Test for human papillomavirus (HPV) infection. This is the preferred follow-up for ASC-US in women 25 and older. HPV infection is the cause of nearly all cancer of the cervix. There are many strains of HPV, some of which can infect the cervix, and only some of these are high risk for causing cervical precancer or cancer. The HPV testing done by clinicians is only for these high risk strains. Use of testing for high-risk HPV gives important information about whether a woman with an ASC-US Pap test is at risk of cervical cancer. HPV testing is often done at the same time as the Pap test. HPV testing is described in detail in a separate topic. (See "Patient information: Cervical cancer screening (Beyond the Basics)".)

Women who test positive for HPV should have colposcopy. Colposcopy is an examination of the cervix using a type of microscope, which is done in the clinician’s office. Colposcopy is discussed in a separate topic. (See "Patient information: Colposcopy (Beyond the Basics)".)

Women who test negative for HPV are not likely to have cervical precancer. These women should have a repeat Pap test and HPV testing in three years. In most cases, the ASC-US resolves during this time.

Repeat the Pap test in one year. If this test is normal, the woman can return to regular screening. If an abnormality is found, then a colposcopy should be done.

HPV testing is not a usual part of screening for cervical cancer for women ages 21 to 24. This is because HPV infection is common in young women, but often goes away and usually does not cause cervical precancer or cancer. For women in this age group with an ASC-US Pap test, there are two options:

Repeat the Pap test in one year.

Another option is to do an HPV test. If the HPV test is negative, the woman can return to regular screening.

Management after colposcopy is discussed separately. (See "Patient information: Management of a cervical biopsy with precancerous cells (Beyond the Basics)".)

Atypical squamous cells, cannot rule out a high grade lesion (ASC-H) — This finding requires further evaluation with colposcopy.

LOW-GRADE SQUAMOUS LESION (LSIL)

An LSIL Pap test shows mild cellular changes. The risk of a high-grade cervical precancer or cancer after an LSIL Pap test is as high as 19 percent [1,3].

As with an ASC-US Pap test, an LSIL Pap test is evaluated differently depending upon age. For women ages 25 or older, follow-up depends upon the results of human papillomavirus (HPV) testing:

Women who test positive for HPV or who have not been tested for HPV should have colposcopy. (See "Patient information: Colposcopy (Beyond the Basics)".)

Women who test negative for HPV can be followed-up with a Pap test and HPV test in one year.

As noted above, HPV testing is not a usual part of screening for cervical cancer for women ages 21 to 24. For these women, an LSIL Pap test should be followed-up with another Pap test in one year.

Management after colposcopy is discussed separately. (See "Patient information: Management of a cervical biopsy with precancerous cells (Beyond the Basics)".)

SPECIAL CIRCUMSTANCES

Pregnant women — The evaluation of pregnant women with an abnormal Pap test is based upon ensuring the appropriate evaluation of the woman while avoiding pregnancy-related complications. In pregnant women, for example, a biopsy of the cervix is only done if there is a high concern regarding a precancerous or cancerous lesion.

Atypical squamous cells of undetermined significance (ASC-US) — Pregnant women with ASC-US are managed in the same manner as other women with ASC-US. If colposcopy is needed, this may be performed during or after the pregnancy.

Atypical squamous cells, cannot rule out a high-grade lesion (ASC-H) — Pregnant women with ASC-H are managed in the same manner as other women with ASC-H.

Low-grade squamous intraepithelial lesion (LSIL) — Pregnant women with LSIL are managed in the same manner as other women with LSIL. If colposcopy is needed, this may be performed during or after the pregnancy.

Postmenopausal women — Postmenopausal women are managed the same way as premenopausal women, with one important exception. If cervical cancer screening is performed in women age 65 or older, ASC-US should be considered abnormal even if human papillomavirus (HPV) testing is negative and should be re-evaluated in one year with a Pap test and HPV testing. However, cervical cancer screening should be stopped at age 65 in women with normal testing according to guidelines from the American College of Obstetricians and Gynecologists, United States Preventive Services Task Force, American Society for Colposcopy and Cervical Pathology, American Cancer Society, and American Society for Clinical Pathology (table 1).

WHERE TO GET MORE INFORMATION

Your healthcare provider is the best source of information for questions and concerns related to your medical problem.

This article will be updated as needed on our web site (www.uptodate.com/patients). Related topics for patients, as well as selected articles written for healthcare professionals, are also available. Some of the most relevant are listed below.

Patient level information — UpToDate offers two types of patient education materials.

The Basics — The Basics patient education pieces answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials.

(See "Patient information: Pap tests (The Basics)".)

(See "Patient information: Cervical cancer (The Basics)".)

This topic currently has no corresponding Basic content.

Beyond the Basics — Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are best for patients who want in-depth information and are comfortable with some medical jargon.

Patient information: Follow-up of high-grade abnormal Pap tests (Beyond the Basics)
Patient information: Cervical cancer screening (Beyond the Basics)
Patient information: Management of a cervical biopsy with precancerous cells (Beyond the Basics)

Professional level information — Professional level articles are designed to keep doctors and other health professionals up-to-date on the latest medical findings. These articles are thorough, long, and complex, and they contain multiple references to the research on which they are based. Professional level articles are best for people who are comfortable with a lot of medical terminology and who want to read the same materials their doctors are reading.

Cervical adenocarcinoma in situ
Cervical cancer in pregnancy
Cervical cancer screening tests: Techniques for cervical cytology and human papillomavirus testing
Cervical cytology: Evaluation of atypical and malignant glandular cells
Cervical cytology: Evaluation of atypical squamous cells (ASC-US and ASC-H)
Cervical cytology: Evaluation of high-grade squamous intraepithelial lesions (HSIL)
Cervical cytology: Evaluation of low-grade squamous intraepithelial lesions (LSIL)
Cervical intraepithelial neoplasia: Terminology, incidence, pathogenesis, and prevention
Cervical intraepithelial neoplasia: Management of low-grade and high-grade lesions
Preinvasive and invasive cervical neoplasia in HIV-infected women
Screening for cervical cancer: Rationale and recommendations

The following organizations also provide reliable health information [4]:

American Society for Colposcopy and Cervical Pathology (www.asccp.org)

American College of Obstetricians and Gynecologists (www.acog.org)

National Cancer Institute (www.cancer.gov)

American Cancer Society (www.cancer.org)

National Library of Medicine (www.nlm.nih.gov/medlineplus/healthtopics.html)

Centers for Disease Control and Prevention (www.cdc.gov/)

Literature review current through: Sep 2014. | This topic last updated: May 17, 2013.
The content on the UpToDate website is not intended nor recommended as a substitute for medical advice, diagnosis, or treatment. Always seek the advice of your own physician or other qualified health care professional regarding any medical questions or conditions. The use of this website is governed by the UpToDate Terms of Use ©2014 UpToDate, Inc.

All topics are updated as new information becomes available. Our peer review process typically takes one to six weeks depending on the issue.