The Pap Smear: Technique and Interpretation

1. The Pap Smear: Technique and Interpretation Karen James, MD January 28, 2003

2. Objectives • Outline pap smear as screening toool • Review cervical histology • Describe proper pap smear technique • Review Bethesda 2001 terminology • Practice management of pap smear results using case studies

3. The Pap Smear

4. Cytologic screening for cervical cancer • Cervical cancer screening has decreased morbidity and mortality • Deaths from cervical cancer decreased from 26,000 to less than 5,000 between 1941 and 1997 • Between 1973 and 1994, the incidence of cervical cancer decreased from 14.2 to 7.8 cases per 100,000 women

5. Pap smears are not perfect • For a high grade lesion, the sensitivity of a single pap smear is only 60-80% • Estimated false negative rate is 30-50% • Requires adequate specimen collection • Requires adequate cytological review

6. Pap smears are not perfect • Requires adequate patient and physician follow-up • 10% of women with cervical cancer had inappropriate follow-up • Requires access to care • 50% of women with cervical cancer were never screened and 10% had not been screened within 5 years of diagnosis

7. Who to screen • Any woman with a cervix who has ever had sexual intercourse • This includes women who have sex with women • This may mean women who have only had digital vaginal penetration

8. When to screen • Start within 3 years of onset of sexual activity or by age of 21, whichever is first • Risk factors for cervical dysplasia • Early onset of sexual activity • Multiple sexual partners • Tobacco • Oral contraceptives, a.k.a. no condoms

9. Screening frequency • Yearly until three consecutive normal pap smears, then may decrease frequency to every three years • ACOG and ACS recommend annual screening for high-risk women

10. When to stop routine screening • Age 65 and “adequate recent screening” • Three consecutive normal pap smears • No abnormal pap smears in last 10 years • No history of DES exposure • No history of cervical or uterine cancer

11. When to stop routine screening • Hysterectomy for benign disease • USPSTF recommends discontinuation • Hysterectomy for invasive cervical cancer • ACOG and ACS recommend continued screening

12. Cervical histology

13. Original Squamous Epithelium • Vagina and outer ectocervix • 4 cell layers • Well-glycogenated (plump and pink) unless atrophic

14. Columnar Epithelium • Upper and middle endocervical canal • Single layer of columnar cells arranged in folds • Mucin producing (not true glands)

15. Squamous Metaplasia • Central ectocervix and proximal endocervical canal • Replacement of columnar epithelium by squamous epithelium • Progressive and stimulated by • Acidic environment with onset of puberty • Estrogen surges causing eversion of endocervix

16. Transformation Zone • Zone between original squamocolumnar junction and the “new” squamocolumnar junction • Nabothian cysts visually identify the transformation zone if present

17. Original Squamocolumnar Junction • Placement determined between 18-20 weeks gestation • Most often found on ectocervix • Can be found in vagina or vaginal fornices in DES exposed women • Less apparent over time with maturation of epithelium

18. “New” Squamocolumnar Junction • Border between squamous epithelium and columnar epithelium • Found on ectocervix or in endocervical canal • Majority of cervical cancers and precursor lesions arise in immature squamous metaplasia, i.e. the leading edge of the squamocolumnar junction

19. Pap Smear Technique

20. Technique • Visualize entire cervix if possible • Carefully remove any obscuring discharge • Sample ectocervix first with spatula • Sample endocervix with gentle cytobrush rotation • Apply material uniformly to slide • Fix rapidly with spray or liquid fixative

21. Technique • Hold spray fixative 10 inches away from slide • Collect cells before bimanual exam • Avoid contamination with lubricant • Test for GC and Chlamydia after pap smear • For DES patients sample cervix and upper 2/3 of vagina

22. Bethesda 2001

23. “Normal” Pap Smear • Negative for intraepithelial lesion or malignancy • Other non-neoplastic findings • Reactive cellular changes • Glandular cells status post hysterectomy • Atrophy • Other • Endometrial cells (women  40 yrs)

24. Epithelial Cell Abnormalities: Squamous • Atypical squamous cells • ASC-US: undetermined significance • ASC-H: cannot exclude HSIL • LSIL: low grade (CIN 1) • HSIL: high grade (CIN 2 - 3) • Squamous cell carcinoma

25. SIL and CIN

26. Epithelial Cell Abnormalities: Glandular • Atypical endocervical, endometrial or glandular cells (NOS) • Atypical endocervical or glandular - favor neoplastic • Endocervical adenocarcinoma in situ • Adenocarcinoma: endocervical, endometrial or extrauterine

27. ASCCP Guidelines