Pap Smear
What is a Pap smear?
A Pap smear (also known as the Pap test) is a medical procedure in which a sample of cells from a woman's cervix (the end of the uterus that extends into the vagina) is collected and spread (smeared) on a microscope slide. The cells are examined under a microscope in order to look for pre-malignant (before-cancer) or malignant ( cancer ) changes.
A Pap smear is a simple, quick, and painless screening test. Its specificity - which means its ability to avoid classifying a normal smear as abnormal -- while very good, is not perfect. The sensitivity of a Pap smear - which means its ability to detect every single abnormality -- while extremely good, is also not perfect. Thus, a few women develop cervical cancer despite having regular Pap screening.
In most cases, a Pap test does identify minor cellular abnormalities before they have had a chance to become malignant and at a point when the condition is most easily treatable. The Pap smear is not intended to detect other forms of cancer such as those of the ovary, vagina, or uterus. Cancer of these organs may be discovered during the course of the gynecologic (pelvic) exam, which usually is done at the same time as the Pap smear.
Who should have a Pap smear?
The guidelines as to who should undergo testing and on what schedule have been a controversial and sometimes confusing matter. These recommendations have also changed over time. There are even some significant differences among the current guidelines, which have been developed by different medical organizations.
Generally, pap screening is recommended for all women who are 18 years old or over or who are sexually active. (For example, a sexually active 16 year old girl should have a Pap smear.)
Although the recommended frequency of testing is usually once per year, a woman's clinician may recommend more frequent Pap smears based upon her personal medical history.
Pregnancy does not prevent a woman from having a Pap smear. Pap smears can be safely done during pregnancy.
For women 65 years or older, current screening guidelines provide that women who have had at least three (3) documented normal Pap smears no longer require screening. Practically speaking, if a clinician sees a woman over age 65 who has not been regularly screened, the clinician generally recommends annual Pap testing three years in a row and then discontinuing screening, or at least decreasing its frequency, if all three Pap smears are normal.
For women who have had a hysterectomy , recent recommendations state that Pap screening can be discontinued as long as the hysterectomy was not done because of cancer or precancerous conditions of the cervix.
Which women are at increased risk for having an abnormal Pap smear?
Some women are more likely to have abnormal Pap smears. One common cause of abnormal Pap smears is smoking . Although smoking is associated with many different cancers, many women do not realize that smoking is linked to cervical cancer.
The genital wart virus, also called the human papilloma virus (HPV), increases the risk of an abnormal Pap smear result.
Other risk factors for abnormal Pap testing include having multiple sexual partners and becoming sexually active at a young age.
How is a Pap smear done?
A woman should have a Pap smear when she is not menstruating. The best time for screening is between 10 and 20 days after the first day of her menstrual period. For about 2 days before testing, a woman should avoid douching or using spermicidal foams, creams, or jellies or vaginal medicines (except as directed by a physician), which may wash away or hide any abnormal cervical cells.
A Pap smear can be done in a doctor's office, a clinic, or a hospital by either a physician or other specially trained health care professional, such as a physician assistant , a nurse practitioner , or a nurse midwife. With the woman positioned on her back, the clinician will often first examine the outside of the patient's genital and rectal areas, including the urethra (the opening where urine leaves the body), to assure that they look normal. A speculum will then be inserted into the vaginal area (the birth canal). The speculum is an instrument that allows the vagina and the cervix to be viewed and examined. A cotton swab is sometimes used to clear away some of the mucus.
A small brush called a cervical brush is then inserted into the opening of the cervix (the cervical os) and twirled around to collect a sample of cells. This sample, because it comes from inside the cervix, is called the endocervical sample ("endo" meaning inside). A second sample is also collected as part of the Pap smear and is called the ectocervical sample ("ecto" meaning outside). These cells are collected from a scraping of the area surrounding, but not entering, the cervical os. Both the endocervical and the ectocervical samples are gently smeared on a glass slide and a fixative (a preservative) is used to prepare the cells on the slide for laboratory evaluation.
A bimanual (both hands) exam usually follows the collection of the two samples for the Pap smear. The bimanual examination involves the examiner feeling the ovaries and uterus with one hand on top of the abdomen (belly) and inserting two fingers of the other hand inside the vaginal canal.
The results of the Pap smear are usually available in 2 to 3 weeks. If a woman has not learned of her results after a month, she should contact her clinician's office.
What are the risks of having a Pap smear?
None. There are absolutely no known medical risks associated with Pap smear screening. (However, there are medical risks from not having a Pap smear.)
How is a Pap smear read (analyzed)?
Pap smear analysis and reports are all based on a medical terminology system called The Bethesda System (TBS). The system was developed (in Bethesda, Maryland) to encourage all medical professionals analyzing Pap smears to use the same reporting system. Standardization reduces the possibility that different laboratories might report different results for the same smear. Standardization and uniform terminology also make Pap smear reports less confusing for the clinicians who request the tests and for their women patients.
TBS was the outcome of a National Cancer Institute workshop that was held in 1988 in an effort to standardize Pap reports. The guidelines address many aspects of Pap smear testing and its results. In 1991, the TBS guidelines were revised and improved. Acceptance of the TBS reporting system in the United States is virtually universal.
The major TBS categories for abnormal Pap smears are as follows: - LSIL - This abbreviation stands for low-grade squamous intraepithelial lesion. (Under the old system of classification, this category was called CIN grade I.)
- HSIL - This abbreviation stands for high-grade squamous intraepithelial lesion. (Under the old system of classification, this category was called CIN grade II, CIN grade III, or CIS.)
The word "squamous" describes the thin, flat cells that lie on the surface of the cervix. "Intraepithelial" refers to the surface layer of cells. A "lesion" means that abnormal tissue is present. These important terms - LSIL and HSIL - are described in greater detail below.
What information is included on a Pap smear report?
The first items on a Pap smear report are for purposes of identification. The report is generally expected to have the name of the woman, the name of the pathologist and/or the cytotechnologist who read the smear, the source of the specimen (in this case, the cervix), and the date of the last menstrual period of the woman.
The Pap smear report should also include the following: - A description of the woman's menstrual status (e.g., "menopausal" (no longer menstruating) or "regular menstrual periods")
- The woman's relevant medical history (e.g., "history of genital warts")
- The number of slides (either one or two, depending on the clinician's routine practice)
- A description of the specimen adequacy
- The final diagnosis (e.g., "within normal limits")
- The recommendation for follow-up (e.g., "recommend routine follow-up" or "recommend repeat smear")
Why is a woman's menstrual status important for the Pap smear?
A woman who is menstruating sheds cells from the lining of her uterus called endometrial cells. If these cells are seen on the Pap smear of a menstruating woman, the report may note "endometrial cells, cytologically benign, in a menstruating woman". The comment that cells are "cytologically benign" means that they do appear not to be malignant. A comment of this nature is absolutely not worrisome, since a menstruating woman may be expected to shed such cells.
However, if a woman is menopausal (no longer menstruating), she would not be expected to be shedding cells from the uterine lining . Therefore, endometrial cells on a Pap report might be indicative of an abnormal thickening of the endometrium , the lining of the uterus. Although the Pap smear is not specifically designed to detect such an abnormality, certainly if these cells are noted in a non-menstruating woman, her physician should consider doing a work-up to determine the cause of the endometrial cells. Sometimes, the cause is endometrial hyperplasia , a precancerous condition of the uterine lining, which can be detected by a relatively simple office procedure called an endometrial biopsy .
If a postmenopausal woman is having a monthly vaginal flow of blood due to being on hormone replacement therapy (HRT), then endometrial cells on the Pap smear may not signify any dangerous abnormality since she is shedding endometrial cells due to the hormone replacement therapy . A physician evaluates the situation of each woman on an individual basis.
Why is a woman's past Pap smear history pertinent?
If a woman has had a history of a cellular abnormality on a previous Pap smear, it is important for her to inform the clinician performing the current Pap smear. The patient should provide the details of any previous problems and treatments so that this information can be noted on the lab form. The past history of the woman helps the person who is reading (interpreting) the current Pap smear. A particular abnormality on previous screening alerts him or her to look more carefully for specific findings on the current Pap smear.
What is the significance of the number of slides that are read?
Does it matter whether one or two slides are prepared? Some clinicians place both samples, the one from inside the cervix and the one from around the outside of the cervix, onto the same slide. Other clinicians prefer to use separate slides. This is a matter of preference based on the style of the individual practitioner and is not a major factor in determining the accuracy of the analysis. The number of slides used should not affect the interpretation. Specifying the number of slides is a technical lab requirement.
When might a Pap smear not be adequate for interpretation?
It is a requirement that the report comment on the adequacy of the smear sample for Pap analysis. If the sample is inadequate, the report details the reason. Examples of problems that might be listed under "sample adequacy" include "drying artifact" or "excessive blood." These comments refer to factors that the person analyzing the smear feels may have interfered with his or her ability to interpret the sample.
Sometimes, a Pap smear report will read "unsatisfactory due to excessive inflammation." Inflammation that is present in the woman's vaginal and cervical areas may make it difficult to interpret the Pap smear. Examples of causes of inflammation might include infections such as the human papilloma virus (HPV), a common viral infection that causes Genital Warts, and Chlamydia , a common bacterial infection. It is very important to identify these sexually transmitted infections because they require special treatment and follow-up.
How is the final Pap smear diagnosis made?
The final Pap smear diagnosis is based on three determining factors: the patient's history, sample adequacy, and the presence or absence of cellular abnormalities. The reader (the person reading the smear) takes into account the woman's history as noted on the lab request by the clinician performing the smear. The reader then decides whether the sample was adequate for interpretation. Lastly, the reader notes whether cellular abnormalities were seen on the slides. If the appearance of the Pap smear does not seem to coincide with the woman's clinical history, a comment may also be made to that effect.
The final diagnosis is a short statement that summarizes what the reader has found. Examples of final diagnoses include: - Within normal limits;
- Absence of endocervical cells on the Pap smear;
- Unreliable Pap smear due to inflammation;
- Atypical squamous cells of undetermined significance ( ASCUS );
- Low-grade squamous intraepithelial lesion (LSIL); or
- High-grade squamous intraepithelial lesion (HSIL)
There may also be additional comments such as "low-grade squamous intraepithelial lesion (LSIL) with human papilloma virus."
What are the possible recommendations for follow-up after a Pap smear?
Once the final diagnosis has been made, the follow-up recommends 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 would 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. Further complicating 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 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.
Whether or not the cause of the absent endocervical cells is known, 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 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) estrogen cream to hopefully heal the inflammation. The Pap smear is then repeated.
Inflammation of the cervix is often due to an infection, such as that caused by the human papilloma virus (HPV), which is responsible for genital warts . The physician may examine a woman for sores that look like HPV lesions. HPV is a sexually transmitted virus that may be spread from one person to another even when the genital sores are not visible. Many sexually active people are carriers of HPV, very often without even knowing they are carriers. It is estimated that up to 60% of sexually active women harbor this virus on their cervix or in their vaginal area. It is not unusual for a woman to be unaware that she has HPV - only to find out that her Pap smear shows evidence of HPV.
HPV is not curable, although the cellular damage it causes is generally treatable. A woman with HPV needs careful and regular long- term medical follow-up to watch for any resulting HPV-associated inflammation and pre-cancerous cellular changes. It is hoped that research-in-progress will yield both a cure and a preventive vaccine against this virus.
Cervical cultures may also be done as part of the follow-up. Samples from the cervix are sent to a laboratory to determine if dangerous or disease-causing bacteria grow from the cervical samples. These cultures may provide evidence of chlamydia or gonorrhea , which are treatable sexually-transmitted bacterial infections that can cause dangerous complications. Microscopic examination of genital secretions may detect trichomonas, another sexually-transmitted organism requiring treatment.
Other less dangerous conditions may also be associated with inflammation. For example, bacterial vaginosis (BV) is characterized by an imbalance of bacteria in the vaginal canal. The predominant symptom of BV is vaginal discharge. BV has certain other characteristics that allow it to be diagnosed relatively easily under the microscope in the physician's office. It often requires no treatment since it does not necessarily cause symptoms. However, it is increasingly believed that BV can be dangerous in pregnant women, even when they have no symptoms, in terms of increasing the risk of pregnancy complications.
In summary, the physician will use clinical judgment in terms of the specific follow-up after a Pap smear that reports inflammation. It may be necessary to test the patient for some or all of the above conditions.
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) or a yeast infection could be the cause of ASCUS. A great deal about ASCUS is unknown. However, one thing certain is that most cases resolve spontaneously, which means 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 treated if ASCUS is again observed on the repeat Pap smear 4 to 6 months later. This standard recommendation - to repeat 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. If not, a colposcopy (see below) may be done without waiting to repeat the Pap smear.
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 3 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.
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).
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. However, even LSIL spontaneously returns to normal without therapy in many women within several months. Many physicians are reassessing the speed and aggression with which they treat LSIL, especially in women who are reliable and financially able to return for consistent follow-up. Therefore, repeat Pap smears every 4 to 6 months for 2 years may be recommended, after which a return to normal screening is possible if there are 3 negative, consecutive, satisfactory Pap smears.
The other option is immediate colposcopy with biopsy (see below), also a reasonable course of action. It is evident from the different practice styles that the decision of when to treat pre-cancerous cervical abnormalities is still somewhat controversial.
The usual cut-off point is LSIL. Cellular abnormalities not serious enough to be categorized as LSIL are not treated immediately, but rather observed. Cellular abnormalities more serious than LSIL are treated immediately. LSIL is somewhere in between.
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 requires the immediate referral of the woman for treatment.
In a 1998 study, records of women spanning a 2 year period were reviewed to follow the natural progression of abnormal Pap smears. This particular study performed repeat Pap smears in 6 months for ASCUS or LSIL. The conclusion was that follow-up Pap smears on women with low grade cellular abnormalities was a reasonable course of action because a large number of these cases returned to normal. A small number of women progressed to HSIL, which was usually detected within 1 year, and was visible most of the time on intervening abnormal Pap smears. In this study, if HSIL was seen on one Pap smear OR persistent ASCUS or LSIL was seen on three repeated Pap smears, a colposcopy was done (see the discussion of colposcopy below).
Cervical intraepithelial neoplasia (CIN): This is the most severe form of high-grade squamous intraepithelial lesion (HSIL). A neoplasia is now within the realm of cancer. 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.
In a recent study, it was found that both mild and moderate dysplasia were more likely to regress to normal than to progress to cervical cancer. Most untreated mild dysplasias reverted to normal within 2 years. There was only a 1% per year risk of progression from mild dysplasia to a more serious dysplasia versus a 16% risk of progression (within 2 years of the initial abnormal smear) for moderate dysplasia. It therefore appears that the risk of progression for a moderate dysplasia is somewhere between that of a mild dysplasia and a severe dysplasia. This news is very encouraging but of course does not eliminate the need for close follow-up by a qualified physician if dysplasia is reported on a Pap smear.
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. However, the cancer is "in situ," which means that it appears to be limited to the cervix and not to have invaded other tissues.
What treatments are available if a Pap smear is abnormal?
If a Pap smear is interpreted as abnormal, there are a number of different treatment options including: colposcopy, conization, Cryocauterization, laser therapy, large-loop excision of the transformation zone.
All of these procedures have essentially the same overall cure rate of over 90%. However, the procedures do vary considerably in a number of other respects and so will be discussed separately.
Colposcopy: Colposcopy is a procedure that allows the physician to take a closer look at the cervix. The colposcope is essentially a magnifying glass for the cervix. For colposcopy to be adequate, the whole cervical lesion, as well as the whole transformation zone (the transition between the vagina-like lining and the uterus-like lining), must be seen.
During colposcopy, the cervix is cleaned and soaked with 3% acetic acid. This acid not only cleans the surface of the cervix but it also allows cellular abnormalities to show up as white areas (called acetowhite epithelium).
If suspicious areas of cervical tissue are seen during colposcopy, a biopsy (tissue sampling) is often done. The sample is sent to the laboratory for analysis and the biopsy results determine the next step in the treatment.
The procedure is essentially painless and quite simple, usually taking only several minutes to perform. Generally, the woman is instructed not to have intercourse, douche, or use tampons for about a week afterwards if a biopsy is done. Pregnancy is not a contraindication to colposcopy. Colposcopy can adequately evaluate 90% of women who have abnormal Pap smear results.
In unusual circumstances, colposcopy does not allow an adequate view of the cervix and another procedure called conization is necessary in order to obtain a tissue biopsy.
Conization: This is the "grandfather" of the procedures that are used to treat Pap smear abnormalities. It is still the standard to which all other methods are compared. Conization allows the entire area of abnormal tissue to be removed and provides the maximum amount of cervical tissue for laboratory evaluation to rule out the presence of invasive cancer. After the cervical area is visualized, generally by colposcopy, a cone-shaped specimen of tissue (perhaps 1/2-1 inch long and 3/4 inch wide) is taken from around the endocervical canal.
Conization is usually done on an out-patient basis provided the woman can be observed until the anesthesia wears off. For three weeks after the procedure, the woman needs to avoid douching and using tampons and refrain from sexual intercourse.
Cure rates close to 100% are achieved with conization as long as the cells along the margins of treatment are normal.
With conization, there are associated risks from anesthesia and postoperative hemorrhage (in about 10% of cases) as well as possible future adverse effects on fertility. Conization is generally performed only on women who have had unsatisfactory colposcopy results, have adenocarcinoma in situ (a diagnosis of cancer), or whose Pap smears suggest they may have some invasion of cancer into the nearby tissue.
Hysterectomy (surgical removal of the uterus and the cervix) for non-cancerous abnormal Pap smears is now rarely done. A hysterectomy is appropriate only for those women who are finished with childbearing and have severe pre-cancerous abnormalities that have been resistant to other treatments. It may also be appropriate for women with certain specific findings after conization.
Cryocauterization: Cryocauterization is a simple and safe procedure. A probe, called a cryoprobe, is first cooled by carbon dioxide and then touched to the abnormal cervical area. This freezes and kills the cells, followed by the sloughing of the abnormal tissue. The cervix is generally frozen for three minutes, thawed for five minutes, and then frozen again for three minutes.
A woman undergoing cryocauterization can expect a watery vaginal discharge for several weeks after the procedure.
Laser therapy : Laser therapy makes use of the principal that laser light can be produced by electricity running through gas. In the treatment of cervical lesions, the gas is usually carbon dioxide. This type of laser can instantly boil water and therefore can also be used to kill and vaporize cells.
When a laser beam is directed (using a tiny wand called a micromanipulator) into the cervix at an area of abnormal cervical tissue, the light energy is converted to heat, which in turn causes cell death, as occurs with cryocauterization. However, the laser apparatus is expensive and its use requires more skill than other treatment options such as cryocauterization. The procedure is also painful and generally requires general anesthesia.
The benefit of laser therapy is that it may cause less cervical scarring as compared to cryocauterization. This in turn may mean that, should the woman need colposcopy in the future, the chances of adequately viewing her cervix may be better after laser therapy.
Large-loop excision (LEEP) of the transformation zone: Large-loop excision of the transformation zone (LEEP) removes the cervical transformation zone using a thin-wire loop to administer electocautery. It allows samples to be collected for additional tissue analysis and can be performed in the office under local anesthesia.
Specialized (more frequent) follow-up is necessary after LEEP. This follow-up includes Pap smears, colposcopy, and sometimes other techniques. When there is no more evidence of abnormal cervical tissue, it may be possible to resume annual screening Pap smears.
What is the follow-up after treatment for an abnormal Pap smear?
Follow-up is crucial. Women who have undergone any one of the above-described treatment procedures require special follow-up schedules for some time afterwards. They must be evaluated and checked at least until the physician is fully convinced that routine Pap smears can be resumed.
What is the current status of human papilloma virus (HPV) typing?
There are over 70 different strains of HPV virus. Based on the observation that certain strains of HPV (for example, types 16 and 18) are more likely to be associated with cervical cancer, some people have advocated testing HPV infected women in order to identify their specific strain of HPV. Following an abnormal Pap smear, this information would then be used to help select the specific treatment strategy. In other words, a physician would more aggressively treat a woman with an abnormal Pap smear if she tests positive for an HPV type that is more likely to be associated with the development of cervical cancer.
However, even the so-called "low-risk" HPV strains can still be associated with cervical cancer at some time in the future and not all of the high-risk HPV strain abnormalities will necessarily result in cervical cancer. Furthermore, the HPV typing is expensive.
The controversy continues, but some recent data suggest that the pendulum is moving in favor of doing the HPV typing. It cannot be overemphasized that this protocol should only be definitely accepted and recommended if the experimental data demonstrates that treating women differently solely based on their HPV typing is safe and effective over the long-term. This specific area requires more research.
What is the current status of the newer Pap smear technologies?
New technologies have been developed to try to circumvent the problem of false-negative Pap smears. False-negative results occur when a disease or condition is present but the test does not detect it. False-negative Pap smears (slides with abnormal cells judged to be "normal") are estimated to be between 5% and 30%.
The new techniques consist of alternative ways to prepare and read Pap smears.
In the new preparation method, cervical cells are obtained as usual but a new technique is used to prepare the slides for analysis. The physician puts the cell sample into a vial of liquid preservative. The cells are then sent to the laboratory where they are filtered and spread on glass slides. This method removes any contamination from blood or mucuous. It was approved by Food and Drug Administration (FDA) in 1996.
As far as the reading of Pap smears, the prepared slides are usually read by cytotechnologists who examine thousands of slides under a microscope every day. Since this can be an exhausting process and perhaps subject to human error, computer systems are now being developed to assist by providing automated analysis of slides. In 1998, the FDA approved one such system for the initial reading of Pap smears. Slides containing abnormally appearing cervical cells can first be identified and then subjected to a second, manual rescreening.
These new technologies are being aggressively marketed. Although they claim to significantly reduce the rate of false-negative Pap smears, they are also very expensive as compared to conventional Pap smears and they have not yet been definitely shown to improve actual medical outcomes. In other words, the question of whether the new technology translates to improved women's health status and quality of life is still unanswered. Many physicians believe that the new technologies are likely to provide minor benefits and only to those women who are already at low risk for abnormal Pap smears (i.e., those who already have access to conventional Pap smears).
With Pap smears so available, why are women still dying of cervical cancer?
It is critically important to recognize that the women who are at highest risk for abnormal Pap smear testing are those who are NOT getting regular Pap testing. Therefore, it follows that in order to improve overall Pap smear screening, women who are not getting regular Pap smears should be educated about and offered Pap testing. These under-served women should be actively targeted for Pap screening.
Between 60% and 80% of American women who are newly diagnosed with invasive cervical cancer have not had a Pap smear in the past five years and may never have had one. Women who have not had Pap smear screening tend to be concentrated in certain population groups including: - Older women;
- The uninsured;
- Ethnic minorities, especially Latina, African American, and Asian American women;
- Poor women; and
- Women in rural areas.
Many physicians feel that the emphasis should be on universal access to proper Pap screening as opposed to the comparatively small benefit that would come from utilizing the newer technologies in women already undergoing screening. Cervical cancer is one of the most common causes of cancer worldwide. It is also one of the most preventable and treatable cancers.
Historical note: Dr. Pap
The Pap smear is named after Dr. George Papanicolaou (1883-1962). Born in Greece, Papanicolaou received a medical degree from the University of Athens in 1904 and a PhD in zoology from the University of Munich in 1910. He came to the United States in 1913 as an assistant research biologist under Dr. Charles R. Stockard at Cornell Medical College in New York City. He stayed at Cornell for 47 years. There, he studied the role of chromosomes in sex determination. In the process, he noticed recurring changes in the cells in the vaginal discharge of the guinea pig over the menstrual cycle . Extending his studies to humans, "Dr. Pap" began examining vaginal smear changes in 1923. He unexpectedly discovered that women with uterine cancer had "abnormal cells, with enlarged, deformed, or hyperchromatic nuclei." He called the discovery of these abnormal cells on the smear "one of the most thrilling experiences in my scientific career."
Dr. Pap's new test was at first viewed as quite unnecessary for the diagnosis of cervical cancer. Then, in 1943, he and the gynecologist Herbert F. Traut published a report entitled "Diagnosis of uterine cancer by the vaginal smear." They demonstrated clearly how cellular abnormalities could be detected before the tumor became invasive. It was a revolution in the management of cervical cancer. The Pap smear test was soon accepted as a routine screening technique. Within two decades, cervical cancer dropped from first to third place as a cause of cancer death in women.
Dr. Pap was the founder of what is called exfoliative cytology, which is the microscopic examination of cells shed from the surface of the body or from a tumor in order to, among other things, detect cancer and gauge the effect of hormones. Dr. Pap applied his technique to other types of tumors including those in the respiratory, gastrointestinal, and urinary tracts and the breast . His method has also been used to predict cancer radiosensitivity and evaluate the effectiveness of radiotherapy . However, it is as the creator of the Pap smear that Dr. Pap is best remembered today.
Pap Smear At A Glance: - A Pap smear is a simple, quick, and painless screening test.
- Cells collected from a woman's cervix are spread on a microscope slide for examination.
- The cells are evaluated for abnormalities, specifically pre- malignant and malignant changes.
- Pap smears are recommended for all women starting at age 18 years or upon becoming sexually active.
- The frequency with which a woman has Pap smears should be recommended by her clinician.
- The Pap smear is read (analyzed) according to a uniform standardized system.
- A woman's health history, including previous Pap smears, is essential to reading the current Pap smear.
- The diagnosis consists of a summary of what has been found on the Pap smear analysis.
- The final diagnosis determines the follow-up and, if appropriate, the treatment options.
- Up to 80% of women diagnosed with invasive cancer of the cervix have not had a Pap smear in the past 5 years.
- Cancer of the cervix is a preventable disease.
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