The test is an invaluable tool in the prevention of cervical cancer and has resulted in a greater than 95% reduction in annual fatalities from cervical cancer since its introduction in the United States.
HOW IT WORKS
A Pap smear is a relatively simple test to obtain, and it is not painful.
A Pap smear begins with the insertion of an instrument called a speculum into the vagina, which opens the vagina and allows visualization of the cervix. The exterior of the cervix (ectocervix) is then gently scraped with a plastic spatula, and the canal (endocervix) is sampled with a brush.
From here, there are two methods of collection and evaluation:
- Liquid Based Pap Smear: This is the preferred method of collection and evaluation. Specimens are gathered in a liquid media and sent to the cytology lab for evaluation where the specimen is processed and plated on a slide. From there, the cells are examined microscopically.
- Conventional Pap Smear: This is the older version of collection and evaluation, in which the collected sample is transferred directly to a glass slide for analysis by the laboratory. Results are reported in approximately one week. Often, a DNA analysis for the presence of high-risk subtypes of Human Papilloma Virus (HPV) is also run on the Pap smear in individuals older than 30 years, known as co-testing. Extensive research has shown that high-risk types of HPV cause the vast majority of cervical cancer. Thus, if the Pap smear is normal and HPV absent, the likelihood of developing cervical cancer during the subsequent five year time interval is almost non-existent, and Pap testing intervals can safely be extended.
The American Society for Colposcopy and Cervical Pathology (ASCCP), the American Cancer Society (ACS), the American Society for Clinical Pathology (ASCP), and the US Preventive Services Task Force (USPSTF) issued updated guidelines for cervical cancer screening in March 2012.
It is recommended that women begin getting regular Pap tests starting at the age of 21 years. Once started, with normal results, a woman is advised to obtain Pap smears a minimum of every 3 years. Women past the age of 65 years, with no histories of significant past abnormalities, can discontinue screening. Depending on individual risk factors, test results, type of additional tests performed (co-testing), and age, as well as other factors, the recommended frequency of Pap screening may vary. However, even if the frequency of Pap screening is extended, it is recommended that women see their Gynecologists annually for examinations.
Most of the time, the test results from a Pap smear will come back normal. If this is the case, no action needs to be taken until the next scheduled test. Abnormal results do not automatically denote cervical cancer. Pap smears are classified and managed based on criteria established by the American Society for Colposcopy and Cervical Pathology (ASCCP) as listed below:
- Negative for Intraepithelial Lesion or Malignancy
- Atypical Squamous Cells of Undetermined Significance (ASCUS)
- Atypical Squamous Cells: Cannot Exclude High-grade Squamous Intraepthelial Lesion (ASC-H)
- Atypical Glandular Cells (AGC)
- Low-grade Squamous Intraepithelial Lesion (LGSIL)
- High-grade Squamous Intraepithelial Lesion (HGSIL)
- Carcinoma reported
If an abnormal test result is found, a colposcopy will be performed to evaluate the abnormality.
Colposcopy utilizes a magnification lens and a high power light source to evaluate the cervix. Areas on the cervix that appear abnormal (with the aid of painting the cervix with vinegar) are usually biopsied, in which a sample of cervical tissue is removed and analyzed by a pathologist to obtain a diagnosis of the abnormality seen. If the Pap smear findings of ASCUS or LGSIL are confirmed by colposcopy, then watchful waiting and interval follow ups are generally recommended, as these types of findings do not pose significant risks for developing into cancer and usually resolve on their own with clearance of HPV infection.
COMPLICATIONS AND TREATMENT
When HGSIL is confirmed or diagnosed, treatment is usually performed, as these abnormalities are less likely to clear on their own and pose greater risks for progression to cervical cancer.
Treatment is usually by the Loop Electrosurgical Excision Procedure (LEEP) where the cervical abnormality is removed using a wire loop attached to electrocautery with careful follow up. In the unlikely event where invasive cervical cancer is diagnosed, a referral to a Gynecologic Oncologist is made for management and treatment.