Atypical Squamous Cells of Undetermined Significance (ASC-US)


The Pap test your clinician recently performed has shown some abnormal changes of the cervix called Atypical Squamous Cells of Undetermined Significance (ASC-US)(pronounced “ask-us”). Squamous cells are the thin flat cells that form the surface of the cervix. The squamous cells do not appear completely normal, and sometimes the changes are related to HPV infection, inflammation or a precancerous change. ASC–US are considered mild abnormalities. Approximately 3-7% of all Pap tests result in a diagnosis of ASC-US. Although ASC-US is an abnormal result that requires additional follow-up, it is important to understand that a diagnosis of ASC-US does not necessarily mean that you have cervical cancer.

Pap Test Background Information

The Pap test (sometimes called a Pap smear) is a way to examine cells collected from the cervix (the lower, narrow end of the uterus). The main purpose of the Pap test is to find abnormal cellular changes that may arise from cervical cancer or before cancer develops. A Pap test and pelvic exam are important parts of a woman’s routine healthcare because they can detect abnormalities that may lead to invasive cancer of the cervix. These abnormalities can be treated before cancer develops. Most invasive cancers of the cervix can be prevented if women have Pap tests regularly. Also, as with many types of cancer, cancer of the cervix is more likely to be treated successfully if it is detected early. Women should talk with their healthcare provider about when and how often they should have a Pap test. Current general guidelines recommend that women have a Pap test at least once every three years, beginning about years after they begin to have sexual intercourse, but no later than age 21. About 55 million Pap tests are performed each year in the U.S. Of these, approximately 3.5 million (or 6%) are abnormal and require medical follow-up.

Follow-up and Treatment Options

Repeat Pap Test:
Since your Pap test has shown a minor abnormality, your healthcare provider may repeat the test to determine whether further follow-up is needed. Many times, cellular changes in the cervix go away without treatment. If treatment is necessary, your doctor may choose to follow up with one of the options below.

HPV Test:
Your clinician may choose to perform an additional test for Human Papillomavirus (HPV). HPV testing in women with ASC–US may help identify underlying abnormalities that need a doctor’s attention. A negative HPV test can provide reassurance that cancer or a precancerous condition is not present. The HPV test can be performed on your previous Pap test if it was collected with the liquid based methodology. If not, a second sample may be collected to perform this test.

Your healthcare provider may decide to perform an additional test called a colposcopy. In this procedure, an instrument similar to a microscope is inserted through the vagina and used to view the cervix directly. Your healthcare provider will be able to see the surface of the cervix clearly during the procedure and will look for any abnormal areas.

If areas of abnormal cells are seen during the colposcopy, your healthcare provider may biopsy (remove a small tissue sample) and send it to a laboratory for study under a microscope. Often, multiple areas of the cervix are biopsied during the procedure. While a Pap test is a screening test, a biopsy is a diagnostic test and will provide a definitive diagnosis.

Questions to Ask Your Healthcare Provider
  • Is this diagnosis going to progress into something more severe?
  • What type of follow up do you suggest and why?
  • What are the potential risks or side effects to this option?
  • When do you recommend a repeat Pap test?
Sources for Additional Information

The content of this web page and corresponding downloadable handout is provided to you as general information and not intended as a diagnosis. Please consult with your personal physician regarding the essential details about your condition. Updated 12/2013.

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