Pap Smear Screening Guidelines and Interpretation
Cheryl A. Glass and Rhonda Arthur
A.The Pap smear is a sample of cells taken from the cervix for cytological evaluation. The Pap smear is a screening test designed to increase detection and treatment of precancerous and early cancerous lesions, and to decrease morbidity and mortality from cases of invasive cervical cancer.
B.In the United States, approximately 13,000 new cases of cervical cancer occur annually. Of these cases, approximately 4,200 deaths occur. Cervical cancer is the seventh most common cancer in women. Since the 1950s, there has been a 70% reduction in the incidence of cervical cancer due to the use of Pap smear screening.
C.Human papillomavirus (HPV) increases the risk for cancer, including cervical, vulvar, vaginal, penile, and anal cancer as well as cancer of the oropharynx. Because cervical cancer is believed to be caused by sexually transmissible HPV infections, women who have not had sexual exposures are likely at low risk. Women aged older than 21 years who have not engaged in sexual intercourse may not need a Pap test depending on circumstances. The decision should be made at the discretion of the women and her physician. Women who have had sex with women are still at risk of cervical cancer.
D.The other risk factors for development of cervical cancer:
1.Early age at first intercourse: younger than 18 years.
2.Multiple sexual partners: more than three in a lifetime.
3.High parity.
4.Lower socioeconomic status.
5.Advanced age.
6.Compromised immune system: infection with HIV.
7.Smoking.
8.Male partner with a history of multiple partners or sexually transmitted infections (STIs).
9.History of STI, especially HPV.
10.Diethylstilbestrol (DES) exposure in utero.
11.Cervical dysplasia: The risk of carcinoma is 100 times greater in women with dysplasia than in those with a normal cervix.
E.The Pap smear should include sampling from both the ectocervix and the endocervix to be considered adequate for interpretation.
The ectocervix is the cervical portion extending outward from the external cervical os. The endocervix extends upward from the external os to the internal os, where the cervical epithelium meets the uterine endometrium. See Section II: Procedure for Pap Smear and Maturation Index Procedures.
F.Cervical epithelium is composed of squamous and columnar cells. Squamous epithelium, appearing smooth and pink, lines the vagina and continues upward to cover variable amounts of the ectocervix. Columnar epithelium, darker red and more granular in appearance, lines the endometrium and continues downward to the cervix, lining the endocervical canal. The boundary between squamous and columnar epithelium is called the squamocolumnar junction (or transformation zone) and may occur anywhere on the ectocervix or endocervix.
G.The squamocolumnar junction may regress at various times as a result of hormonal variation, particularly with sexual activity and during pregnancy, through processes known as epidermidalization and squamous metaplasia. Epidermidalization is an upward growth of squamous cells that replace columnar cells. Squamous metaplasia is the differentiation of columnar cells into squamous cells. The area between the original and new squamocolumnar junction is called the transformation zone. When columnar epithelium is visible on the ectocervix, appearing as a granular, red area, it is referred to as eversion, ectropion, or ectopy. This is often seen in pregnancy or with oral contraceptive use.
H.Cervical cancer is a progressive disease with a number of histologically definable stages. Invasive cancer of the cervix and its precursors are detectable by cytology before becoming symptomatic and before gross clinical signs appear. When symptoms are present, they usually include (in order of frequency) postcoital spotting; intermenstrual bleeding, especially after exertion; and increased menstrual bleeding. Patients with invasive cancer may experience serosanguineous or yellowish vaginal discharge, which may be foul smelling and intermixed with blood.
I.Advanced disease may cause urinary or rectal symptoms, including bleeding. On speculum examination, advanced lesions appear as necrotic ulcers; in invasive disease they may extend upward or protrude into the vagina.
J.See Section II: Procedure for Pap Smear and Maturation Index Procedures.
Bethesda System
The 2014 Bethesda system is the most current classification system used to interpret cytological findings. Naya, R., & Wilbur, D. C. article ” The Pap Test and Bethesda 2014″ published in Acta Cytologica is available for download at www.karger.com/Article/Pdf/381842.
A.Specimen type (conventional cytology collection, liquid based, and high-risk HPV [hrHPV] cotesting).
B.Adequacy of the specimen using conventional method:
1.Satisfactory for evaluation.
2.Presence or absence of endocervical or transformational zone components.
3.Quality indicators such as obscuring blood or inflammation.
4.Unsatisfactory for evaluation and specific reason.
C.General categorization:
1.Negative for intraepithelial lesion or malignancy.
2.Epithelial cell abnormality.
3.Other.
D.Interpretation/result:
1.Squamous cell abnormalities:
a.Atypical squamous cells of undetermined significance (ASCUS): Indicates some abnormality but cause is unclear (infection common).
b.Atypical squamous cells: Cannot exclude highgrade squamous intraepithelial lesion (HSIL; ASC-H).
c.Low-grade squamous intraepithelial lesion (LSIL): Indicates HPV, mild dysplasia, or cervical intraepithelial neoplasia (CIN) I.
d.HSILs: Moderate and severe dysplasia, carcinoma in situ or CIN II, and CIN III.
e.Squamous cell carcinoma.
2.Glandular cell:
a.Atypical glandular cells (AGCs).
b.AGCs favor neoplastic.
c.Adenocarcinoma.
3.Other: endometrial cells in women older than 40.
Management of Abnormal Pap Smears
A.See Appendix E for three of the American Society for Colposcopy and Cervical Pathology (ASCCP) Algorithms for the Updated Consensus Guidelines for Managing Abnormal Cervical Cancer Screening Tests and Cancer Precursors:
1.Unsatisfactory cytology algorithm.
2.Management of women older than age 30 who are cytology negative, but HPV positive.
3.Management of women with LSIL.
The full ASCCP consensus management guidelines and algorithms are available in pdf format for personal use at www.asccp.org/asccp-guidelines. They are available in English and Spanish.
The ASCCP Mobile App Presentation is also available for Android, iPhone, iPad, available for download on the Android App Store, Apple App Store, and at Amazon.
Recommendations
A.The American Cancer Society, the ASCCP, and the American Society for Clinical Pathology clinical guidelines recommended screening strategies with cytology or cotesting (cytology in combination with hrHPV) by age-specific guideline. The American Congress of Obstetricians and Gynecologists (ACOG) recommends screening for women ages 21 to 65 with cytology alone, and HPV cotesting by agespecific guideline. The 2017 draft U.S. Preventive Services Task Force (USPSTF) recommendation statement for cervical cancer notes for women ages 21 to 65 years screening for cervical cancer with cervical cytology alone and hrHPV testing alone dependent on the woman’s age. See Table 2.4 for cervical cancer screenings recommendations for average-risk women. Women who are infected with HIV who are otherwise immunocompromised (e.g., solid organ transplants), women previously treated for CIN2 or CIN3 or cancer, and women exposed to DES before birth need more frequent screening.
B.The Advisory Committee on Immunization Practices recommends routine vaccination of females and males aged 11 to 12 with two doses of quadrivalent or 9-valent HPV vaccine 6 months apart, and states the series can be started as young as 9 years of age. Catchup vaccination is recommended for adolescents and young adults aged 13 to 27. A third dose is required for people with weakened immune systems and those who start the vaccine when they are older than 15.
C.Patient education regarding the prevention of cervical cancer by avoiding exposure to HPV should include reduction or elimination of high-risk activities. These high-risk activities include having sexual intercourse at an early age, having multiple sexual partners, having partners with multiple partners, and having sex with uncircumcised males. Use of condoms can reduce the risk of HPV as well as other STIs. Smoking cessation can also reduce the risk of cervical cancer. Identification and treatment of precancerous lesions can reduce the risk of invasive cervical cancer, so screening according to ACS guidelines should be encouraged.
Treatment Modalities
Treatment is instituted based on the severity of the lesion and the presence of pathology within the columnar epithelium of the endocervix. Treatment options include the following:
A.Observation and repeat cytology.
B.Cryotherapy.
C.Loop excision of the transformation zone.
D.Laser of the transformation zone.
E.Cold-knife conization.
F.Observation and repeat cytology.