CancerLinkThe Pap test is a screening test for malignant and premalignant changes of the cervix. A positive result indicates that there may be a problem and that further diagnostic procedures must be done to. The Pap test is not a diagnostic test. It cannot be used to exclude a cancer of the cervix for a person who has symptoms that could be due to a cervical cancer.
Pap tests are done on women who have no symptoms of cancer and have no findings suggesting a cancer. Thus, Pap tests are done only on women who are normal. If the woman has symptoms or findings suggestive of cancer of the cervix then a diagnostic test must be done to exclude a cancer or to diagnose a cancer. Diagnostic tests are usually biopsies. This is the single most important lesson to learn: if you have a symptom or a finding that could be due to a cancer of the cervix, a normal Pap test never excludes the possibility of cancer.
In the vast majority of instances, an abnormal Pap test results in the diagnosis of a minor change on the cervix. Some of these changes will be premalignant, but most will be of minor significance. They will all have to be evaluated, diagnosed and treated, but most will be easily and effectively treated. Occasionally, a real cancer will be present which is why this is such an important test. Most cancers are visible on examination and can be biopsied as soon as they are seen. Sometimes the cancers are inside the cervix beyond view and the only indication that it is there is the abnormal Pap test.
The Pap test is performed by gently scraping cells from the cervix, smearing them onto a microscope slide and sending it to a pathology laboratory for evaluation. There are two reporting systems in current use. The older system reported the result in one of five classes.
| Class I | Normal. |
| Class II | Atypical, inflammation or endometrial cells seen. |
| Class III | Compatible with dysplasia, mild, moderate or severe. |
| Class IV | Compatible with carcinoma-in-situ. |
| Class V | Compatible with a cancer. |
| Adequacy: | Satisfactory. Limited. Unsatisfactory. |
| Descriptive: | Normal. Benign. Epithelial cell abnormality. Atypical squamous cells of undetermined significance. Low-grade squamous intraepithelial lesion. High-grade squamous intraepithelial. Glandular cell abnormality. Atypical glandular cells. Adenocarcinoma. |
Squamous (squay-mus) means flat and refers to the flat cells at the surface. This covering is called a squamous epithelium. In addition to the progression of the shape of the cells from the lowermost large round cells to the outermost flat cells, the nuclei of the cells also change. Those cells lowermost along the basement membrane have a large nucleus that becomes progressively more compact and smaller as the cells approach the surface. On exposed squamous epithelium such as skin the outermost cells have lost their nuclei completely and the cells are filled with keratin to produce a protective keratin layer. On the cervix there is normally no keratin layer and the outermost cells have a very small dense nucleus.
When there is a disorder of the normal progression of cells from the lower to outermost layer then that is called a dysplasia. If this disorder of maturation is limited to the inner third of the epithelium then that is a mild dysplasia; if two-thirds of the thickness then a moderate dysplasia; if almost the full thickness then a severe dysplasia. If the outermost cells look the same as those along the basement membrane then that is a full thickness disorder and is called a carcinoma-in-situ. A carcinoma-in-situ is a premalignant change and can become a cancer if not treated. It is thought that there is a progression from mild to moderate to severe dysplasia before developing carcinoma-in-situ. It may take years for this progression to develop into a cancer. Often the early changes will resolve spontaneously. If these dysplastic cells penetrate the basement membrane and invade into the deeper tissues then that is a cancer.
There are other terms for these dysplastic changes. The more modern term is intraepithelial neoplasia, grade I, II and III. The term carcinoma-in-situ, CIS, has been dropped since the word carcinoma means cancer and this is not a cancer. CIN III, cervical intraepithelial neoplasia grade III, means a full thickness dysplasia and has replaced CIS. These premalignant changes can only be diagnosed by a biopsy of the cervix. The pathologist has to have a piece of tissue to evaluate not just a collection of scraped off cells. The Pap test is just a collection of scraped off cells. If these are abnormal, i.e. large round cells with a large nucleus that should not be on the surface, the pathologist can recognize them and report the test as abnormal. But, he cannot diagnose the true condition without an adequate biopsy specimen. Obtaining an adequate tissue biopsy specimen is the result of a comprehensive evaluation of the cervix following the report of an abnormal Pap test.
Abnormal blood vessels can also be seen. Neoplasia means new growth. New growth means new blood vessels. Often these new blood vessels are abnormal. These abnormal vessels can be seen through the colposcope. The worse the vessels appear the worse is the dysplasia. Cancers have the worst vascular appearance of all the changes that can occur on the cervix.
During a colposcopic examination the first determination is if there are abnormal areas. If so, can the entire abnormal area be seen? If so, then the most abnormal areas are biopsied. If the entire abnormal area cannot be seen then that cervix cannot be evaluated colposcopically. Usually the abnormal area extends up into the endocervical canal beyond view. In this case the canal must be removed to evaluate the cervix adequately. There are several techniques for removing the canal. Sometimes a cone biopsy is done. This removes a circular portion of the cervix extending up the canal to an apex. The specimen is shaped like a cone. A more modern technique that can be done in the office is called a LEEP. This means Loop Electrosurgical Excision Procedure, and removes portions of the cervix with an electrified thin wire loop.
If the colposcopic evaluation is satisfactory, meaning all the abnormal areas can be seen, then the most abnormal areas are biopsied and sent to the pathologist. The pathology report will indicate the diagnosis. It will be either something minimal, some degree of dysplasia, or CIN, possibly even a cancer. But whatever it is, it is the diagnosis, and the abnormal Pap test has been evaluated. If the colposcopy is unsatisfactory, then either a cone biopsy or a LEEP needs to be done and the pathological report of that material will be the diagnosis. If a specimen is scraped from the endocervix ( endocervical curettage, ECC) and shows dysplasia then a cone or LEEP also is indicated. Only after a diagnosis has been established can treatment be recommended.
If a cone biopsy or LEEP were done that had removed the abnormal areas it would be therapeutic as well as diagnostic. Otherwise, the abnormal area can be destroyed by freezing (cryocautery), vaporization (laser), removal by biopsy, cone, LEEP, or even hysterectomy if necessary. Hysterectomy may be best in certain circumstances, but is seldom a medical necessity for dysplasia. If the biopsy shows an invasive cancer then staging procedures need to be done and appropriate treatment given. This is an entirely different problem and will usually require referral to an oncologic specialist.
Once a premalignant condition has been treated then the woman should be reexamined every three months for at least a year and have a Pap test done. If all goes well then she should be reexamined annually. If the woman was pregnant when the abnormal Pap test was found and examination at that time was not suggestive of cancer then her definitive examination and biopsy can be deferred until six weeks postpartum.
If you have been told that your Pap test indicates the presence of HPV, do not be alarmed. If a definite viral change can be seen with the colposcope then it can be obliterated with cryocautery, laser or left alone. Only dysplasias need to be treated. You are not at great risk for developing cervical cancer. Continue to have annual Pap tests and treat any dysplasia if it is diagnosed.
Where did the HPV come from? Who knows, it may have been there for years. The point is that it is unknowable; there is no way to find out. Since it is of no demonstrable detriment to your health it is not worth the time worrying about where it came from. Some studies have demonstrated that about one third of college students have evidence of past or present infection with HPV. It is not unusual to find it reported on Pap tests in women in their seventh decade.
When a woman has a symptom such as bleeding after intercourse, bleeding between periods, or foul watery discharge then a cancer of the cervix must be excluded. Only a thorough examination and biopsies can rule out a cervical cancer. A Pap test cannot rule out a cancer. A cervical cancer is usually visible on examination. If the cervix looks abnormal it must be biopsied. A Pap test cannot rule out a cancer. If a woman has symptoms that could be caused by a cervical cancer and the cervix looks normal then a biopsy from inside the endocervical canal must be done. A biopsy from inside the uterus may also be necessary. A Pap test never rules out a cancer. It cannot be repeated too many times "a normal Pap test never rules out cancer".
Another error is to treat on the basis of the Pap test rather than on the basis of the diagnosis. An abnormal Pap test never leads to treatment. An abnormal Pap test is not a diagnosis. Treatment cannot be performed until a diagnosis is obtained. An abnormal Pap test leads to diagnosis by colposcopy and biopsy, then to treatment. If a simple hysterectomy is done because of an abnormal Pap test, most women will have had an unneeded hysterectomy. If a cancer is present, a simple hysterectomy may be fatal. Cancers cannot be treated by simple means.
Many women do not obtain annual Pap tests. Many who do think that a normal Pap test means that they are cancer free. The Pap test evaluates only the squamous epithelium covering the visible part of the cervix. The endocervical canal has a glandular epithelium that is not easily evaluated by Pap tests. This glandular epithelium can also become malignant and not be detected. Cancers of the uterus, ovaries and fallopian tubes are not usually detected by the Pap test.
The Pap test is an excellent screening test. It is easy to do, easy to interpret, easy to evaluate when abnormal and most importantly can find changes before they become malignant. These premalignant changes are easy to treat. Cancers are hard to treat.
William M. Rich, MD
Last updated 2 July 1996