What Does an Abnormal Pap Smear Mean?

Causes range from mild inflammation to cancer

swab for Pap smear
What does your abnormal Pap smear result mean?. Istockphoto.com/Stock Photo©DETart21

If you have been told you have an abnormal Pap smear, your first instinct may be to panic or to fear the worst. It’s a natural response.

But what does "abnormal" actually mean within the context of a Pap smear, and what do you need to do if you have one?

Understanding Abnormal Pap Smears

An abnormal Pap Smear simply means that a microscopic examination of cells taken from your cervix was not as the lab technician would have expected.

There can multitude of reasons for this, running the gamut from a mild inflammation to cervical cancer.

In the end, all it really tells us is that your cervix needs further evaluation. In some cases, you might be stepped up to a colposcopic exam and biopsy; at other time, you might be asked to come back for a repeat Pap smear in three years.

Abnormal Pap smears are actually quite common. According to the Centers for Disease Control and Prevention (CDC), approximately three million women receive abnormal Pap smear results each year. Of these, around 12,000 (or roughly one in 250) will progress to cervical cancer.

Cellular Abnormalities and the Development of Cancer

Cellular abnormalities are referred to as dysplasia. The actual classification of dysplastic cells include:

  • ASCUS (atypical squamous cells of undetermined significance)
  • LGSIL (low grade squamous intraepithelial lesion)
  • HGSIL (high grade squamous intraepithelial lesion)
  • AGC (atypical glandular cells on a Pap smear)

The vast majority of dysplastic cells do not change or ever cause problems. Of those that do change, some will become precancerous, meaning that there is a chance they will become cancerous.

Some of these cells will then progress to a stage of disease called carcinoma in situ wherein the cells become cancerous but are confined to what is called the base membrane (the layer which separates cervical tissue from underlying connective tissue).

It is only when it spreads beyond the basement membrane that the disease is formally classified as cervical cancer.

ASCUS Pap Smears

ASCUS (atypical squamous cells of undetermined significance) is the most common type of abnormality, accounting for around 75 percent of all abnormal readings.

Squamous cells help make up the exterior tissue of the cervix called the intraepithelial layer. ASCUS simply means that the cells have changed but are not suggestive of precancer. The changes can be caused by vaginal infection or, most often, a sexually transmitted infection called human papillomavirus (HPV).

SIL Pap Smears

SIL (squamous intraepithelial lesion) refers to the abnormal changes in squamous cells that have formed into a lesion. SIL is not a diagnosis of precancer or cancer. They are simply abnormalities graded on their size, shape, and physical characteristics, as follows:

  • LGSIL (low-grade intraepithelial cells) are mildly abnormal, often due to an HPV infection. Many of these infections go away without treatment.
  • HSIL (high-grade intraepithelial cells) refer to changes which may be associated with the development of precancerous cells.

AGC Pap Smears

AGC (atypical glandular cells) are another type of cell that cover the inner canal of the cervix as well as the uterus.

An AGC result means that changes in these cells raise concern about the presence of either precancer or cancer.

What Happens If You Have an Abnormal Pap Smear

Your doctor may recommend additional tests if an abnormal Pap smear result is received. It will depend largely on the lab classification, your current health, and the experience of your treating doctor.

Possible approaches can include:

  • watchful monitoring with routine repeat Pap smear screening
  • HPV testing (including reflex HPV testing which utilize cells from the Pap smear)
  • colposcopy and biopsy of any abnormal tissue
  • endocervical sampling (a procedure in which the mucous membrane of the cervical canal is scraped using a spoon-shaped instrument called a curette)
  • endometrial sampling (the removal of a sample of tissue from the uterus if your doctor suspects the abnormal cells are from the uterus)
  • Excisional treatment (cone biopsy) to remove a lesion or growth

Guidelines for follow-up vary by age, dysplasia classification, and the woman’s HPV status:

 

Age 21-24

Age 25-29

Over 30, HPV-negative

Over 30, HPV-positive

ASCUS

Repeat Pap in 12 months (preferred)

Reflex HPV (acceptable)

Reflex HPV (preferred)

Repeat Pap in 12 months (acceptable)

Repeat Pap and HPV test in 3 years

Colposcopy

LSIL

Repeat Pap in 12 months

Colposcopy

Repeat Pap in 12 months (preferred)

Colposcopy (acceptable)

Colposcopy

ASC-H

Colposcopy

Colposcopy

Colposcopy

Colposcopy

HSIL

Colposcopy

Excisional treatment or colposcopy

Excisional treatment or colposcopy

Excisional treatment or colposcopy

AGC

Dependent on AGC subcategory

Dependent on AGC subcategory

Dependent on AGC subcategory

Dependent on AGC subcategory

Source:

American College of Obstetrics and Gynecology (ACOG). "Abnormal Cervical Cancer Screening Test Results." Washington, D.C.; updated January 2016; FAQ 187.

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