Optimizing the Papanicolaou Smear

Goals and Objectives

Background
  1. History of Cervical Ca Screening Techniques
    • 1925 - Hans Hanselman introduces colposcope.
    • 1926 - Aureli Babes publishes on cytologic screening. Little publicity.
    • 1928 - Papanicolaou presents findings on cytologic screening.
    • 1941 - Papanicolaou publishes on cytologic screening. Widely read and accepted
    • 1955 - Scheffey introduces colposcopy to the US.
  2. Epidemiologic Proof for Cervical Ca Screening - Why we do it...
    1. MacGregor (1976):
      1. Screened women - invasive cancer rate = 30-50/100,000
      2. Unscreened women - invasive cancer rate = 310/100,000
    2. Fidler (1968):
      1. Screened women - invasive cancer rate = 5/100,000
      2. Unscreened women - invasive cancer rate = 29/100,000
    3. Walton (1976):
      1. Strong correlation between screening intensity and cervical cancer mortality (R=0.72)
    4. Adami (1994):
      1. "Cytologic screening reduces mortality from cervical cancer by earlier diagnosis of invasive disease" Cancer 1994; 73:140-7.
  3. "... a majority of women diagnosed with invasive carcinoma of the uterine cervix do not receive routine pap smears..." NY State J of Med
  4. Epidemiology of Cervical Cancer
    1. 20,000 new cases per year
    2. 7,600 deaths per year
    3. 3.5% of all female deaths per year
    4. 50 million women undergo Pap testing in the U.S. / year.
    5. 3.5 million (7%) are diagnosed with a cytological abnormality requiring additional follow-up or evaluation. JAMA. 2002;287:2120-2129.
  5. Risk Factors for Developing Cervical Cancer
    1. Three or more lifetime sexual partners.
    2. First sexual intercourse before age of 18
    3. Humanpapilloma virus in patient, partner, or partner's partners
    4. Smoking
    5. Maternal DES (diethylstilbesterol) exposure during pregnancy
    6. A previous abnormal Pap smear
  6. Risk Factors - Conclusions
    1. Only a small percentage of women are classified as low risk.
    2. The vast majority of women have one or more risk factors and are considered at greater risk for developing cervical cancer.

Pap Smear Terminology:

  1. Previous Systems and the Bethesda System
    Pap Classes
    Description
    Bethesda 2001
    I
    Normal
    Normal and variants
    II
    Reactive Changes
    Reactive Changes
    Atypia
    ASC, ASG
    Koilocytosis
    Low Grade SIL

    III CIN I

    Mild dysplasia
    Low Grade SIL
    III CIN II
    Moderate dysplasia
    High Grade SIL
    III CIN III
    Severe dysplasia
    High Grade SIL
    IV
    Ca in situ, suspicious
    High Grade SIL
    V
    Invasive
    Microinvasion (<3mm)
    Frankly invasive (>3mm)
    CIN = cervical intraepithelial neoplasia, SIL = squamous intraepithelial lesion
  2. Pap Classes Are Out Because:
    1. Do not reflect current understanding of pathology
    2. Classes not transferrable to histology terms
    3. No classes for non-cancerous entities
    4. No longer uniform
    5. Years of experience have demonstrated a lack of reproducibility
  3. To put it another way... One man's dysplasia is another man's carcinoma-in-situ.

The 2001 (revised) Bethesda System

  1. Important Changes Over Older Systems:
    1. Pap considered a Medical Consult
    2. Pathologist responsible for diagnosis
    3. Referring physician provides history
    4. Must have a statement of adequacy
    5. Recommendations regarding follow-up should be made by pathologist
  2. The Bethesda System Report Includes:
    1. Whether the pap is an adequate sample
    2. Incidental findings such as evidence of infection
    3. Evidence of lesions: low-grade SIL, high-grade SIL, or cancer
  3. New Bethesda System Classification Terms:
    1. Low-grade squamous lntraepithelial lesion (low-grade SIL)
      1. Cellular changes associated with HPV
      2. Mild (slight) dysplasia/CIN 1
    2. High-grade squamous intraepithelial lesion (high-grade SIL)"
      1. Moderate dysplasia/CIN II
      2. Severe dysplasia/CIN III
      3. carcinoma in situ/CIN III
    3. Atypical Squamous Cells (ASC)
      1. Unspecified (ASC-US) - includes uspecified and favor benign/inflammation
      2. Cannot exclude HSIL (ASC-H)
    4. Atypical Glandular Cells of Uncertian Significance (AGC) AGC is broken down into favoring endocervical, endometrial, or not otherwise specified origin or endocervical adenocarcinoma in situ (AIS)
      1. Unspecified (AGC-US)
      2. Atypical glandular cells, favor neoplastic (AGC-H)
  4. Endocervical cells - Used to determine the adequacy of a pap smear.
    1. Statistically significant relationship between patient age/fertility state and yield of endocervical cells.
  5. Miscellaneous
    1. "Atypia" is used only if undetermined significance and should include a recommendation for follow-up. (ASC and ASG)
    2. Descriptive diagnosis should be given to common problems (changes due to trich, yeast, etc.) Do not trust Pap smear to diagnose or exclude infections!!
    3. Metaplasia - The physiologic conversion of columnar endocervical cells to flat exocervical squamous cells. Norman finding - no special follow-up needed.
    4. "Parakeratosis" is a term for the persistence of the nuclei of the keratinocytes into the stratum corneum (horny layer) of the skin. Parakeratosis is normal in the epithelium of true mucus membranes of the mouth and vagina.
    5. "Dyskeratosis" is a term for abnormal, premature, or imperfect characterization of the keratinocytes.
    6. Hyperkeratosis implies increased keratin in the sample and should be followed-up closely since there may be an increased risk of cancer. J Fam Pract 1993; 33:354-8.

Points About the PAP

  1. Highly effective for screening only. It is not diagnostic. It only identifies those at risk for dysplasia or cancer.
  2. False Negative Pap Smears: Rate = 5 - 50% -- 10 - 29% usually quoted. 80% are true false negatives, 20% are lab errors
  3. Repeating cervical smears.
    1. LSUHSC Study: "Using follow-up cervical smears to monitor patients who have low-grade SILs carries unacceptable risks, and a diagnostic test such as colposcopy is indicated." J Fam Pract 1995; 40:57-62
    2. ASCCP Consensus Guidelines recommend routine colposcopy instead of repeated Paps since follow-up cytological studies have usually had high rates of loss to follow-up, a 53% to 76% likelihood of abnormal follow-up cytology results requiring eventual colposcopy, and a small but real risk of delaying the identification of invasive cancers.
  4. Inadequacies in Pap Smear Screening
    1. False negative Paps
    2. Failure to identify high risk patient at entry.
    3. Inaccurate or incomplete reports from the lab to clinic to patient
    4. Lack of adequate tracking and follow-up.
    5. Poor patient compliance.
  5. Summary of lesions missed by Pap:
    1. Occur outside of a large eversion.
    2. Small lesions.
    3. Advanced invasive lesions since they have infection and necrotic tissue, which can obscure the true cytology. Koss, JAMA. 1989:737.
    4. Rapidly progressive lesions.
    5. Lesions deep in the cervical canal.
  6. Factors That Diminish the Accuracy of Pap Smears - Clinician Factors
    1. Contamination with blood or oil-based lubricants
    2. Mislabeled or unlabeled slides
    3. Inadequate clinical history
    4. Inadequate sampling of the transformation zone
    5. Slide material too thick or insufficient
    6. Performing pap in spite of obvious infection
  7. H. Factors That Diminish the Accuracy of Pap Smears - Laboratory Factors
    1. Confusing smears or names
    2. Failure to identify dysplastic cells
    3. Misinterpretation of diagnostic cells
    4. Poorly controlled technical process

Screening Intervals: 2002 ACS Recommendations for Detection of Cervical Cancer

  1. The guidelines are based on a literature review combined with expert opinion when sufficient evidence was not available. The ACS guidelines suggest a movement toward less excess screening. A comparison of ACS guidelines with the USPSTF guidelines on screening for cervical cancer is shown in Table 1.
    TABLE 1: Comparison of ACS guidelines with the USPSTF Guidelines on Screening for Cervical Cancer
    Criteria USPSTF guideline ACS 2002 guideline
    Age to initiate screening Optimum age unknown; within 3 years of onset of sexual activity or age 21 Three years after the onset of sexual activity; no later than age 21
    Screening frequency At least every 3 years Annually with conventional cytology or every 2 years with liquid-based cytology. After age 30, women with 3 consecutive normal tests may be screened every 2-3 years.
    Screening after hysterectomy No cytologic testing after total hysterectomy for benign condition No cytologic testing after total hysterectomy for benign condition
    Discontinuation After age 65 (see below) After age 70 (see below)
    Routine screening for HPV infection Insufficient evidence Not yet FDA approved. If approved, conventional or liquid-based cytology combined with test for DNA from high-risk HPV subtypes should be performed not more often than every 3 years
    USPSTF = U.S. Preventive Services Task Force; ACS = American Cancer Society; HPV = human papillomavirus; FDA = U.S. Food and Drug Administration.
    Saslow D, Runowicz CD, Solomon D, Moscicki AB, Smith RA, Eyre HJ, et al. American Cancer Society guideline for the early detection of cervical neoplasia and cancer. CA Cancer J Clin 2002;52:342-62.
    U.S. Preventive Services Task Force. Screening for cervical cancer: recommendations and rationale. AHRQ Publication No. 03-515A. Rockville, Md.: Agency for Healthcare Research and Quality, 2003.
  2. Cervical cancer screening should begin three years after the onset of vaginal intercourse or by age 21. Data suggest that there is little risk of missing an important cervical lesion until three to five years after initial exposure to human papillomavirus (HPV). Screening before the three-year period may result in overdiagnosis of cervical lesions that would regress spontaneously. An upper age limit is necessary for health care professionals who do not ask patients about their sexual history and for adolescents who are unable or unwilling to disclose prior consensual or nonconsensual intercourse. The need for cervical cancer screening should not be the basis for the onset of gynecologic care.
  3. Screening should be performed annually with conventional cervical cytology smears or every two years using liquid-based cytology. After age 30, women who have had three consecutive normal tests can be screened every two to three years unless they have a history of in utero exposure to diethylstilbestrol (DES), are infected with human immunodeficiency virus (HIV), or are immunocompromised by organ transplantation, chemotherapy, or chronic corticosteroid treatment.
  4. Cervical cancer screening can be discontinued at age 70 in women with an intact cervix who have had at least three documented, consecutive, normal cervical cytology tests and no abnormal tests within the previous 10 years. Women who have a history of cervical cancer or in utero exposure to DES and women who are immunocompromised (including those infected with HIV) should continue cervical cancer screening as long as they are in good health.

Guidelines for Obtaining a Pap Smear

  1. Visual inspection of the lower genital tract and cervix through the speculum is a prerequisite to optimal sample collection.
  2. The location and appearance of the transformation zone is variable depending on such factors as vaginal pH, pregnancy, hormonal mileu (age), prior therapy, and individual anatomy.
  3. An optimal cervical specimen includes sampling of the squamous and columnar epithelium, encompassing in particular the transformation zone, where the majority of cervical neoplasias arise.
  4. Collecting the Pap Smear
    1. Label the frosted end of the glass slide with the patient's name prior to collection.
    2. Insert the speculum, which may be moistened with water or saline if necessary. Traditionally, no other lubricants are recommended. However, a recient blinded study in 182 patients randomly assigned to have either only warm water or a water soluble lubricant to assist speculum insertion, only 2 unsatisfactory smears were found among 93 patients with the lubricant and two were found among 89 using only warm water. They concluded that use of a water soluble lubricant on the vaginal introitus and external speculum facilitates examination with no adverse effect on Pap smear interpretation. Harer WB. Valenzuela G Jr. Lebo D. Lubrication of the vaginal introitus and speculum does not affect Papanicolaou smears. Obstet Gynecol 2002; 100:887-8. However, do not use any lubricants other than water or saline on Thin-prep slides since they plug the filter and may produce an unsatisfactory smear.
    3. Visually inspect the cervix for abnormalities.
    4. Identify the transformation zone and direct sampling efforts to encompass this area.
      1. The endocervical limit of the transformation zone is dynamic, defined by the leading edge of the migrating squamo-columnar junction.
      2. In post menopausal women, it is often high in the endocervical canal and not visible.
  5. Collecting the Pap Smear - Spatula
    1. Choose the contoured end of the spatula which best conforms to the cervix and the transformation zone.
    2. Rotate the spatula 360o about the circumference of the cervix, while maintaining firm contact with the epithelial surface.
    3. With a clockwise rotation beginning and ending at 9 o'clock (or counter-clockwise rotation from 3 o'clock to 3 o'clock), the collected material is retained on the upper horizontal surface as the instrument is removed.
    4. Do not smear the sample at this time unless you immediately fix the specimen. Hold the spatula between the fingers of the non-sampling hand (or rest it on the glass slide with the specimen face-up), while the cervical brush material is collected.
    5. Spread the material collected on the spatula evenly over the slide with a single smooth stroke motion.
  6. Collecting the Pap Smear - Cervix Brush
    1. These brushes have circumferential bristles that come into contact with the entire os surface on insertion.
    2. The brush need only be turned 1/4 turn.
    3. Roll the brush across the slide by twirling the handle.
    4. Not currently recommended for pregnancy.
  7. Collecting the Pap Smear
    1. The object is to quickly but evenly spread the cellular material in a monolayer on the slide.
    2. Thin out large clumps of material as much as possible, while avoiding excessive manipulation which can damage cells.
    3. Transfer material from both sampling instruments to the slide within a few seconds and fix immediately in order to avoid air-drying artifact.
    4. Immediately fix the specimen by either immersing the slide in 95% ethanol or coating the slide with a surface fixative.
  8. Spatula & Brush - 3 Options for Transferring Material:
    1. Option #1
      1. Smear the spatula on the upper half of the slide.
      2. Roll the brush across the lower half of the slide.
      3. Immediately fix slide.
    2. Option #2
      1. Smear the spatula sample across the slide; roll the brush material directly over the previously spread sample.
      2. Immediately fix slide.
    3. Option #3
      1. Smear the spatula sample over the left-hand side of the slide, cover the right-hand side with cardboard and immediately spray fix.
      2. Roll the brush material onto the right-hand side of the slide and spray fix.
  9. Collecting the Pap Smear - Plastic "Broom"
    1. Another collection instrument, a plastic "broom-like" brush (Cervex-brush or Papette), simultaneously samples the endocervix and ectocervix.
    2. To use the "broom," insert the long central bristles into the os until the lateral bristles bend against the ectocervix. Rotate 3-5 times in both directions.
    3. To transfer material, stroke both sides of the "broom" across the glass slide. Place second stroke exactly over the first stroke.
  10. Collecting the Pap Smear - Cotton Swab
    1. The use of a cotton tip applicator is not recommended. It usually provides less cellular samples, possibly because of trapping of material in the cotton fibers.
    2. "...one third of the cases with false negative cytologies were limited by lack of an endocervical component; all but one were obtained with the cotton swab" Germain et al, Obstet Gynecol 1994; 84:168-73.

 


E.J. Mayeaux, MD
updated 7/29/05

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