Dr. Preeti Tandon
(Specialist Obstetrics & Gynaecology Laparoscopic & Robotic Surgeon. )

MBBS, MD(Obs/Gynae), F.MAS(Laparoscopic Surgeon), FICOG
Diploma in Adv Gynae Endoscopy (France), Certified Robotic Surgery Training (USA).

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PAP Smear

What is a Pap smear?

A Pap smear, widely known as pap test, is a kind of medical procedure involves the collection of the sample of cells from woman’s cervix( cervix is at the end of the uterus that extends into the vagina) and put it on the microscopic slide. These collected cells are keenly examined under a microscope in order to find pre-malignant (before-cancer) or; malignant (cancer) changes

A Pap test is very quick and painless screening test. Its specificity which means its competency to avoid classifying a normal smear as abnormal - while very good, is not perfect

The sensitivity of a Pap smear – which called its competence examine every single abnormality -- while good, is also not perfect, and some "false negative" results (in which abnormalities are present but not detected by the test) will occur. Thus, a few women develop; cervical cancer des

In most of the cases, a Pap test does can easily minor cellular abnormalities which are minor before they have had a chance to become severe and at a point when the condition can be easily encountered by treatment. The Pap smear is not proposed to identify other forms of cancer such as those of the ovary, vagina, or uterus. Cancer in these mentioned organs may be get discovered during the time of the gynecologic (pelvic) exam, which is generally done at the same time as the Pap smear

Who should have a Pap smear?

Pregnancy is not the worth condition that prevents a woman to undergone a Pap smear. Pap smears are safely done during the course of pregnancy as well.

Pap smear testing is not desired for women who have undergone hysterectomy (with the removal of the cervix) for benign conditions. Women who have undergone a hysterectomy which not involves the removal of the cervix, called subtotal hysterectomy, should continue the screening test following the same guidelines as women who have not undergone a hysterectomy

Some of the screening guidelines of many key medical organizations are summarized in the below-mentioned table

Organization When to start Pap smear testing Frequency of Pap smeaer testing 

At what age to stop having Pap smears

American Cancer Society2004

3 years after involved in sexual intercourse, 21 is the limit Yearly with exceptions


  • every 2 years if liquid-based kit
  • every 2-3 years if three normal tests in a row in women >30 years old
  • Total hysterectomy for benign disease
  • > 70 years old with at least three normal Pap smear results and no abnormal Pap results in the last 10 years

United States Preventative Services Task Force 2003

Within the span of 3 years of onset of sexual activity or age 21, whichever happens first At least every 3 years (no evidence that every year is better than every 3 years)
  • Recommend against doing Pap smears in women older than 65 years of age, if adequate screening with normal results and otherwise not at risk for cervical cancer.
  • Recommend against doing Pap smears in women who have had a total hysterectomy for benign disease.

American College of Obstetrics and Gynecology

3 years after first sexual intercourse or age 21, whichever comes first. Yearly until age 30 years. Beginning at age 30, if three normal annual Pap results, can do a Pap alone every 2-3 years Difficult to set an upper age limit-postmenopausal women screened within the prior 2-3 years have a very low risk of developing abnormal Pap smears.

Which women are at higher risk for having an abnormal Pap smear?

  • Many risk factors have been identified pave for the development of cervical cancer and precancerous changes in the cervix.
  • HPV:The prime risk factor is infection with the genital wart virus, also known as the human papillomavirus (HPV), however, significant no. of women with HPV infection do not get affected by cervical cancer. (See below for details). The percentage of between 95%-100% of cervical cancers is closely related to HPV infection. Some women are more likely to develop abnormal Pap smears when put in comparison with other women.
  • Smoking: One of the most common risk factors for the changes (premalignant and malignant) in the cervix is because of smoking. Although smoking is closely associated with many different types of cancers, but many women do not realize that smoking is strongly linked to cervical cancer. Smoking always plays a catalyst in increasing the risk of cervical cancer about two to four times.
  •  Weak immune system:Women whose immune systems are susceptible to disease or have become weak by the regular medicines (for example, those undergone for organ transplant) also possess a higher risk of precancerous changes in the cervix.
  • Medications: Women whose mothers who are in the habit of taking the drug diethylstilbestrol (DES) during pregnancy also at the higher risk of cancer.
  •  Other risk factors:Other significant risk factors for precancerous changes in the cervix and Pap testing (abnormal) include – sexual intercourse with multiple sexual partners and becoming sexually active at a tender age.

How is a Pap smear done?

A woman always tries to undergo Pap smear when she is not in the course of menstruation cycle. The optimal time for the screening test is between 10 and 20 days after the first day of menstrual cycle. Tentatively, about two days before testing, a woman must avoid aforementioned things, like douching or using spermicidal foams, creams, or jellies or any sort of vaginal medicines (except as directed by a physician). It is recommended because these agents may wash away or abnormal cervical cells may hide.

A Pap smear test can be performed in a doctor's office, a clinic or a hospital comfortably by either a physician or other professionally trained health care practitioner, such as a physician assistant, or a nurse practitioner. In this test, woman will be positioned on her back and the medical practitioner will often first examine the exact situation of the outside of the areas of patient's genital and rectal, including the urethra (the opening where urine leaves the body), to ensure everything is normal.

Further, a speculum is inserted into the birth canal or medically known vaginal area. (Speculum is defined as an instrument that allows the vagina and the cervix to be examined keenly)

  • A cotton swab is generally used to clear mucus that might interfere with the original sample.
  • A cervical brush (small in the dimension) is then inserted into the opening of the cervix (the cervical os). It is for the collection for the original cells. Because this original sample comes from inside the cervix, is called the endocervical sample (endo referred to inner).
  • A second sample will be collected as a part of the Pap smear and referred as the ectocervical sample, here ecto refers to 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 put on a glass slide for the further examination and a fixative a kind of preservative is used to prepare the cells on the slide for the keen examination in the laboratory.

A bimanual (performed by both sides) pelvic exam usually performed by the collection of the two samples for the Pap smear test. This examination involves the physician inserting two fingers of one hand inside the canal of the vaginal area while feeling the ovaries and uterus with the other hand on top of the abdomen (belly).

The results of the Pap smear test are usually delivered within 2 to 3 weeks’ time. At the end of course of Pap smear testing, each woman must enquire how she should inform about the results of her Pap smear. If a woman is not getting his results, even after a month time, then it is highly advisable for her health care practitioner's office.

What are the risks of having a Pap smear?

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)?

The detailed analysis and reports of Pap smear are relied on a medical terminology system, referred as The Bethesda System. The system was formally developed (at the National Institutes of Health (NIH) in Bethesda, Maryland) to place all medical professionals on the same board for the reporting system to examine Pap smear. This process of standardization greatly reduces the every possibility of producing different result reports for the same smear. This convention and the uniform terminology also make Pap smear reports pretty less perplexed for the clinicians who request for the tests and for their women patients.

The Bethesda System was the result of a National Cancer Institute workshop that was happened in the year of 1988 in an effort to make the standard convention for Pap reports. The mentioned guidelines address many crucial aspects of Pap smear testing and its desired outcomes. In the year of 2001, these guidelines were revised by the result of many detailed studies. The Acceptance of the Bethesda reporting system is universal in the United States.

Some of the major categories for abnormal Pap smears reported in the Bethesda Systems are below mentioned:

  • ASC-US: This abbreviation referred as the atypical squamous cells of undetermined value. As per the aged system of classification, this mentioned category was refereed as atypical squamous cells just ASC. The new system requires the reader to single out one of two choices to add at the end of ASC: ASC-US, which means undetermined significance or ASC-H, which means cannot exclude HSIL-see below.
  • LSIL: This abbreviation referred as the low-grade squamous intraepithelial lesion. As the aged system of classification goes, this category was formerly called CIN grade I.
  • HSIL: This abbreviation referred as the high-grade squamous intraepithelial lesion. As the aged system of classification goes, this category was called CIN grade II, CIN grade III, or CIS.

The term "squamous" is explained as thin, flat cells that lie on the surface of the cervix. The term "Intraepithelial" indicates that the surface layer of cells is affected. A "lesion" means that abnormal tissue is present. These important terms - LSIL and HSIL - are explained in keen detail below.

What information is included on a Pap smear report?

The first item can be seen on a Pap smear report are for the identification purpose. The report generally has the name of the woman, the name of the concerned pathologist and/or the cytotechnologist who read that report, the source of the specimen (in this case, cervix is the specimen) and the date of the last menstrual period of the woman.

The Pap smear report should also include the following:

  •  A detailed description of the status of woman's menstrual cycle. Like "menopausal", which means no longer menstruating or "frequent menstrual periods"
  •  The woman's recent and medical history of relevant treatment, for example, "history of genital warts".
  •  The number of slides, they are either one or two. It also relies on the health care practitioner's routine.
  •  A short yet explanatory description of the specimen adequacy (whether the sample is sufficed for interpretation).
  •  The final diagnosis (for example, "within normal limits")
  • The recommendation for the follow-up, for example, the recommendation of routine follow-up" or "recommend repeat smear".

Why is a woman's menstrual status crucially important for the Pap smear?

A woman who is in the course of menstruation sheds cells from the lining of her uterus called endometrial cells. If these cells are clearly visible on the Pap smear of a woman during menstruation, the report may note "endometrial cells, cytological benign, in a menstruating woman. The comment that cells are "cytological benign" describing that they do appear not to be malignant (cancerous) cells. A comment of this nature is absolutely not seen as trepidation since for menstruating women, this is regular exercise.

Nonetheless, if a woman is menopausal or simply put, no longer menstruating, then she will not be shedding cells from the lining of uterine. Endometrial cells on a Pap report are the indication of an abnormal thickening of the endometrium the lining of the uterus. The Pap smear is not particularly destined to identify such an abnormality. However, if these cells are identified in a non-menstruating woman, her physician must try to find the cause of the shedding of the endometrial cells.

Sometimes, the main reason is endometrial hyperplasia, a precancerous condition of the uterine lining, which can be identified by a simple office methods referred as endometrial biopsy. Some of the times, menopausal hormone therapy can pave the way for the shedding of endometrial cells that seen on a Pap smear. The identified pattern of bleeding, the particular hormone therapy, and the specific woman's health history are the three important things that can guide the physician to evaluate whether and what sort of further examination is needed.

Why is a woman's past Pap smear history pertinent?

If a woman has a past of a cellular abnormality on any previously attempted Pap smear, then it is highly important for her to meet with the health care practitioner who can professionally perform the current Pap smear. The patient must open up about every detail of any previous complications and treatments so that this info can be for the future course treatment. The history of treatments and complications of the woman assists the person who is interpreting the current Pap smear test, because a specific complication on previous screening give a sense of caution to the medical practitioner and assist him to look and find more specific findings on the current Pap smear.

When might a Pap smear not suffice 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 cervical area may make it difficult to interpret the Pap smear. Examples of causes of inflammation might include infections or irritation. Inflammation is a common finding on pap smears. If it is severe your doctor may want to try to determine the cause of the inflammation. In many cases a repeat pap smear is recommended to determine if the inflammation has resolved and to obtain a sample that is adequate for interpretation.

How is the final Pap smear diagnosis made?

The final Pap smear diagnosis is based on three determining factors:

  1. The patient's treatment history: The interpreter (the person identify the insights in the smear) takes a look into account the woman's treatment history as noted on the lab request by the clinician performing the test.
    • Sample adequacy: The interpreter then decides whether the sample was sufficed for the interpretation.
    • The presence or absence of cellular abnormalities: Then interpreter notes whether cellular abnormalities were are identified on the slides. If it appears that Pap smear does not coincide with the woman's clinical history, a comment may also be made to that effect.

The final diagnosis is only a crisp statement that summarizes what the interpreter has found in the report. Examples of final diagnoses include:

    •  Within the defined normal limits;
    •  No-presence 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).

Some additional comments may also be there such as "low-grade squamous intraepithelial lesion (LSIL) with human papilloma virus.";

What are the most likely recommendations for follow-up after a Pap smear?

Once the findings of final diagnosis have been made, the follow-up recommendation assist you what the most appropriate next step(s) you can take. For example, if the final diagnosis interprets that the smear was "within the defined limits," the appropriate follow-up step may be "recommend the routine follow-up."

An abnormal Pap smear is defined as one in which the laboratory identify the cellular changes to be different from those likely seen on a healthy cervix. There can be many follow-up possible follow-up scenarios for an abnormal Pap smear.

Absence of endocervical cells on the Pap smear: There is a specific area where the cells lining the vagina change to the endocervical cells that shows the inside of the cervix. This is referred as the "transition zone" and it is the ultimate target of the endocervical sample. However, it may be so far up deep inside the cervix that the instrument of collecting sampling simply cannot go to that height. To further worsening the situation, the transition zone in a woman frequently changes its position at different times in the whole life span and under different conditions. Often, the zone of transition may be less accessible to the Pap brush or the cervical opening cannot be visible enough to obtain an inside picture and the required sample. Sometimes the main reason for the nonpresence of endocervical cells on the Pap smear can’t be identified.

Regardless of the cause of the absence of endocervical cells is well-known or vague, the situation must be handled and evaluated by the professional. In everyday medical practice, the optimal response to the absence of endocervical cells is to redo the Pap smear, but a determining factor of a woman's prior history into account is determining the timing. If the woman has a past of regular Pap smears and never had an abnormal one, and does not possess a risk factor for an abnormal Pap smear, then the professional will often wait about a year before repeating the smear. If the woman has any associated risk factors, then the clinician will recommend repeating the smear sooner.

Unreliable Pap smear due to inflammation: If the case is of severe inflammation is there, its cause(s) must be identified. The physician's aims are to find the cause of inflammation and to treat and resolve the condition, if possible. Untreated inflammation can pave the way for grave consequences for the woman and for her sexual partner.

Sometimes, the woman's medical treatment past will enlighten on the cause of inflammation. For example, a woman may complain of some irritation, dryness, or mild pain in her vaginal area. The inflammation then must be verified by the physician during a pelvic. The vaginal irritation may arise because of lack of estrogen, such as occurs after menopause when the ovaries stop functioning and stop hormone production. This scarcity of estrogen makes the vaginal walls irritable and red. If a woman has this kind of 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 highly recommend a trial of topical (locally- applied) vaginal estrogen (cream, vaginal estrogen tablets vaginal estrogen ring) to hopefully treat the inflammation. The Pap smear is then repeated.

To put it simply, the physician will use all the aspects of clinical judgment in terms of the specific follow-up after a Pap smear that reports the causes inflammation.

Atypical squamous cells of undetermined significance (ASCUS): Many times, atypical squamous cells which have a very underrated significance (also called "ASCUS"), is mentioned on the Pap report. This can be considered as the lowest form of cellular abnormality on the cell’ ranging from normal to cancerous. ASCUS means that the cells appear abnormal but not malignant.

""Underrated significance" means that the cells looking atypical-appearing may be the result of a number of myriad injuries to the cervix. For example, the human papilloma virus (HPV) can be said to because of ASCUS. Most instances of ASCUS (80%-90%) resolve instantly (by themselves without any sort of particular medical intervention). This can be the reason why many women found with ASCUS readings will be asked to simply go through a repetitive Pap smear in 4 to 6 months. The expectation is that irrespective of the prime cause of the ASCUS, it will get resolved with time the Pap smear is repeated. If this not happens, then the cause of the ASCUS can still be identified and treated successfully if ASCUS is again observed on the repeat Pap smear 4 to 6 months later. This medical recommendation of serial Pap smears - repeating the Pap smear within 4 to 6 months - is made unless the physician has any concern in mind that the woman is not interested or able to return for a repeat Pap smear. For these specific cases, a colposcopy (see below) can be performed 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 is a process in which the HPV test is only performed if the Pap smear results are turned abnormal. For reflex testing, a liquid-based Pap testing kit is essential which allows the lab to store the required sample until the Pap smear result direct them whether the HPV test will be essential or not. A point to be noted that not all the facilities have access to the liquid-based cytology specialized kits. If repeat smears are performed for monitoring, then the testing have to be performed in every 4 to 6 months for 2 years until there have been three consecutive normal smears. The Pap smears, though, must not only be negative but also clear for the good interpretation, as per the guidelines of National Cancer Institute Workshop.

The irritation around the genital area that comes with menopause can pave the way for ASCUS by causing inflammation. If the physician identified that this is the prime 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 has gone. If the inflammation still there, colposcopy will become necessary. Sometimes, the ASCUS reading is accompanied by a comment to the effect that the Pap smear reader interpret there may be a suggestion of dysplasia(abnormally dividing or abnormal appearing cells), often called as "favor dysplasia." Well, in that case, the ASCUS is generally not identified with the time but rather treated as if it is dysplasia (see discussion below). On the same lines, a woman who is having bad immune system is not in ideal condition for serial Pap smear tests because she is at higher risk of many grave abnormalities. Therefore, she should go for colposcopy in place serial Pap smears. So it has become clear from this discussion that myriad factors go into a physician's decision regarding which of the three treatment options he/she can recommend in a particular case of a woman.

Low-grade squamous intraepithelial lesion (LSIL): A serious cellular abnormality is low-grade squamous intraepithelial lesion (LSIL). A reading of LSIL is the reason behind for instant further investigation because it is more abnormal than ASCUS. About, 15% to 30% of women who have this kind of abnormality on Pap testing will have a more serious abnormality while on biopsy of the cervix. Thus, all women with the LSIL are highly advised to undergo colposcopy. On the other hand, even LSIL instantly returns to the normal condition without therapy in many women within some months. That is the prime reason, if the initial colposcopy and biopsy results turn favorable for serial Pap smears every 4 to 6 months may be highly advised 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 considered is not actually cancer is high-grade squamous intraepithelial lesion (HSIL). A single finding of HSIL unquestionably requires instant treatment.

Women with HSIL possess a 70%-75% chance of having a more serious chance of 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. Colposcopy is undoubtedly the highly recommended for all women with HSIL.

Cervical intraepithelial neoplasia (CIN): This is considered as the one of the severe forms of the high-grade squamous intraepithelial lesion (HSIL). A neoplasia comes under the realm of cancer. Type 1 CIN is "low grade," or less serious than Type 2, 3 CIN (high-grade). The identification of a cervical intraepithelial neoplasia (CIN) on a woman's Pap smear means that she needs to be treated as soon as possible.

Carcinoma in situThis particular diagnosis is also a form of high-grade squamous intraepithelial lesion (HSIL). A reading of "carcinoma in situ" on a Pap smear report confirms the presence of cervical cancer. However, the cancer is "in situ," which means that it appears to be confined to the cervix and not to have touched other tissues.

What treatments are available if a Pap smear is abnormal?

In case, if a Pap smear is interpreted as abnormal, there can be many number of different management and treatment options available including colposcopy conization, cryocauterization, laser therapy, and large-loop excision of the transformation zone

All these mentioned procedures have the same overall cure rate of over 90%. Though every procedure does vary in a number of other respects and we will discuss them particularly.

Colposcopy: Colposcopy is a method that allows the doctor to access a closer look at the cervix. The colposcopy is a magnifying glass to look into 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 examined.

During the course of colposcopy, the cervix is keenly washed and soaked with 3% acetic acid. This acid not only cleans the surface of the cervix but allows cellular abnormalities to show them as white areas (called act white epithelium or act white lesions).

If any of the suspicious areas of cervical tissue are seen during the course of colposcopy a biopsy (tissue sampling) is often applied. Then the sample is sent to the laboratory for the further analysis by a seasoned pathologist and the biopsy results evaluate the next step.

This procedure is often painless and simple and takes to perform. It is highly recommended for the woman not to have intercourse, douche, or use tampons for about a week afterward if a biopsy is performed. Pregnancy is not considered as the contraindication to colposcopy.