Pap Smear (cont.)
Melissa Conrad Stöppler, MD
Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.
William C. Shiel Jr., MD, FACP, FACR
Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.
In this Article
- Pap smear facts
- What is a Pap smear?
- Who should have a Pap smear?
- Which women are at increased risk for having an abnormal Pap smear?
- How is a Pap smear done?
- What are the risks of having a Pap smear?
- How is a Pap smear read (analyzed)?
- What information is included on a Pap smear report?
- Why is a woman's menstrual status important for the Pap smear?
- Why is a woman's past Pap smear history pertinent?
- When might a Pap smear not be adequate for interpretation?
- How is the final Pap smear diagnosis made?
- What are the possible recommendations for follow-up after a Pap smear?
- What treatments are available if a Pap smear is abnormal?
- What is the follow-up after treatment for an abnormal Pap smear?
- What is the current status of human papilloma virus (HPV) testing?
- When should women start and stop having Pap smears, and how often should Pap smears be performed?
- What is the current status of the newer Pap smear technologies?
- With Pap smears so available, why are women still dying of cervical cancer?
- Historical note: Dr. Pap
- Find a local Obstetrician-Gynecologist in your town
What are the possible recommendations for follow-up after a Pap smear?
Once the final diagnosis has been made, the follow-up recommendation informs you what the appropriate next step(s) might be. For example, if the final diagnosis states that the smear was "within normal limits," the appropriate follow-up might be "recommend routine follow-up."
An abnormal Pap smear is one in which the laboratory interprets the cellular changes to be different from those normally seen on a healthy cervix. There are a number of possible follow-up scenarios for an abnormal Pap smear.
Absence of endocervical cells on the Pap smear: There is a particular area wherein the cells lining the vagina change to the endocervical cells that characterize the inside of the cervix. This is called the "transition zone" and is the target of the endocervical sample. However, it may be so far up inside the cervix that the Pap smear sampling instrument simply cannot reach that high. To further complicate the situation, the transition zone in a woman migrates (changes its position) at different times in her life and under different conditions. Sometimes, the transition zone may be less accessible to the Pap brush or the cervical os (opening to the cervix) cannot be seen well enough to obtain an adequate sample. Sometimes, the reason for the absence of endocervical cells on the Pap smear is simply not evident.
Regardless, if the cause of the absent endocervical cells is known or unknown, the situation must be evaluated by the physician. In everyday practice, an appropriate response to the absence of endocervical cells is to redo the Pap smear, but also to take the woman's prior history into account in determining the timing. If the woman has had regular Pap smears, has never had an abnormal one, and does not have an added risk factor for an abnormal Pap smear, then the clinician will often wait a year before repeating the smear. If the woman does have risk factors, the clinician will often elect to repeat the smear sooner.
Unreliable Pap smear due to inflammation: If severe inflammation is present, its cause(s) must be investigated. The physician's goals are to identify the cause of inflammation and to treat and resolve the condition, if possible. Untreated inflammation can have consequences for the woman as well as her sexual partner(s).
Sometimes, the woman's medical history will shed light on the cause of inflammation. For example, a woman may complain of irritation, dryness, or pain in her vaginal area. The inflammation can then be verified by the physician during a pelvic exam. The vaginal irritation may be caused by a lack of estrogen, such as occurs after menopause when the ovaries stop producing this hormone. This lack of estrogen tends to make the vaginal walls irritated and red. If a woman has this condition and it is related to an estrogen deficiency (called "atrophic vaginitis" and usually described on the Pap smear report as "atrophic changes"), her physician may recommend a trial of topical (locally- applied) vaginal estrogen (cream, vaginal estrogen tablets, vaginal estrogen ring) to hopefully heal the inflammation. The Pap smear is then repeated.
In summary, the physician will use clinical judgment in terms of the specific follow-up after a Pap smear that reports inflammation.
Atypical squamous cells of undetermined significance (ASCUS): Sometimes, atypical squamous cells of undetermined significance (also called "ASCUS"), is the determination written on the Pap report. This is the mildest form of cellular abnormality on the spectrum of cells ranging from normal to cancerous. ASCUS means that the cells appear abnormal but are not malignant.
"Of undetermined significance" means that the atypical-appearing cells may be the end result of a number of different types of injuries to the cervix. For example, the human papilloma virus (HPV) could be the cause of ASCUS. Most instances of ASCUS (80%-90%) resolve spontaneously (by themselves without specific medical intervention or treatment). This is the reason why many women with ASCUS readings will be asked to simply have a repeat Pap smear in 4 to 6 months. The expectation is that regardless of the original cause of the ASCUS, it will be resolved by the time the Pap smear is repeated. If not, the cause of the ASCUS can still be identified and treated if ASCUS is again observed on the repeat Pap smear 4 to 6 months later. This standard recommendation of serial Pap smears - repeating the Pap smear in 4 to 6 months - is made unless the physician has a concern that the woman is not willing or able to return for a repeat Pap smear. In these cases, a colposcopy (see below) may be done without waiting to repeat the Pap smear.
The third approach to ASCUS (besides serial Pap testing and immediate colposcopy) is called reflex HPV testing. Reflex HPV testing refers to a process in which the HPV test is only performed if the Pap smear result is abnormal. If the Pap smear result is normal, it is not performed. For reflex testing to be possible, a liquid-based Pap testing kit is required, which allows the lab to store the sample until the Pap smear result tells them whether the HPV test will be necessary or not. If repeat smears are to be done for monitoring, the testing needs to be done every 4 to 6 months for 2 years until there have been three consecutive normal smears, at which time routine screening can be resumed. The Pap smears, however, must not only be negative, but also satisfactory for interpretation, according to National Cancer Institute Workshop Guidelines.
The irritation of the genital area that accompanies menopause can trigger ASCUS by causing inflammation. If the physician suspects that this is the cause of ASCUS, he or she may prescribe intravaginal estrogen (local estrogen, such as a vaginal ring, vaginal cream, or vaginal estrogen tablets) and repeat the Pap smear in 4 to 6 months to confirm that the inflammation is resolved. If the inflammation persists, colposcopy will be necessary. Sometimes, the ASCUS reading is accompanied by a comment to the effect that the Pap smear reader thinks there may be a suggestion of dysplasia (abnormally dividing or abnormal appearing cells), often worded as "favor dysplasia." In this case, the ASCUS is generally not monitored over time but rather treated as if it is dysplasia (see discussion below). Similarly, a woman who has a suppressed immune system is not a good candidate for serial Pap smear tests because she is at higher risk of serious abnormalities. Therefore, she should undergo colposcopy instead of serial Pap smears. It is evident from this discussion that many factors go into a physician's decision regarding which of the three treatment options to recommend to an individual woman.
Low-grade squamous intraepithelial lesion (LSIL): A more serious cellular abnormality is low-grade squamous intraepithelial lesion (LSIL). A reading of LSIL is a reason for immediate further investigation because it is more abnormal than ASCUS. Fifteen to 30% of women who have this abnormality on Pap testing will have a more serious abnormality on biopsy of the cervix. Thus, all women with LSIL are recommended to undergo colposcopy. On the brighter side, even LSIL spontaneously returns to normal without therapy in many women within several months. For that reason, if the initial colposcopy and biopsy results are favorable, serial Pap smears every 4 to 6 months may be recommended, after which a return to normal screening is possible if there are three negative, consecutive, satisfactory Pap smears.
High-grade squamous intraepithelial lesion (HSIL): The most severe cellular abnormality that is not actually cancer is high-grade squamous intraepithelial lesion (HSIL). A finding of HSIL unquestionably requires prompt treatment.
Women with HSIL have a 70%-75% chance of having a more serious abnormality (CIN 2,3 see below) on biopsy of the cervix, and a 1%-2% chance of having actual cervical cancer on biopsy of the cervix. Therefore, colposcopy is undoubtedly the routine recommendation for all women with HSIL.
Cervical intraepithelial neoplasia (CIN): This is the most severe form of high-grade squamous intraepithelial lesion (HSIL). CIN 1 is "low grade," or less serious than CIN 2 or 3 (high-grade). The diagnosis of a cervical intraepithelial neoplasia (CIN) on a woman's Pap smear means that she needs to be evaluated and treated as soon as possible by a qualified physician.
Carcinoma in situ: This diagnosis is also a form of high-grade squamous intraepithelial lesion (HSIL). A reading of "carcinoma in situ" on a Pap smear report means there is cervical cancer present. However, the cancer is "in situ," which means that it appears to be limited to the most superficial portion of the cervix and not to have invaded more deeply into the cervical tissue.
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