Tips for Improving Specimen Adequacy
Listed below are definitions for Specimen Adequacy utilizing the Bethesda 2001 reporting system, as well as, tips for improving the overall quality of Pap test samples.
Definitions for Specimen Adequacy:
Unsatisfactory for Evaluation
- Any sample in which >75% of the epithelial cells are obscured by inflammation, blood and/or mucus.
- Any sample in which >75% of the epithelial cells are distorted due to poor preservation and air-drying.
- Any sample in which the over all cell yield is <10% of the expected cellularity for a patient within a given age or hormonal status (8,000-12,000 well preserved and well visualized squamous epithelial cells on conventional Pap smears or 5,000 well preserved and well visualized squamous epithelial cells on ThinPrep Pap tests).
Satisfactory, with specimen quality factors noted
- Any sample in which 50-75% of the epithelial cells are obscured by inflammation, blood and/or mucus.
- Any sample in which 50-75% of the epithelial cells are distorted due to poor preservation and air-drying.
- Any sample in which there are fewer than 10 endocervical and/or metaplastic cells, representing sampling of the transformation zone.
- Any sample in which the over all cell yield is between 10-20% of the expected cellularity for a patient within a given age or hormonal status.
- Any sample comprised by 90% endocervical cells, representing an insufficient sampling of squamous cells from the ectocervix.
Factors Effecting Specimen Adequacy and Potential Solutions
Obscuring Blood
There are three main causes for samples being obscured by blood.
- a sample taken during active menses
- a sample which is the result of aggressive sampling
- a sample collected from a friable cervix
To reduce the number of bloody samples consider the following.
- have patients schedule visits at mid-cycle whenever possible
- if using an endocervical brush for cell collection, the recommended protocol is to rotate the device ¼ to ½ turn. Do not over rotate.
- if using a combination of a spatula and an endocervical brush for specimen collection, the sample collected with the spatula should be collected first.
- utilization of the ThinPrep technique, reduces the number of cases reported as limited by blood by greater than 50%
Obscuring Inflammation
While there is no way to improve a conventional Pap smear which is limited by inflammation, utilizing the ThinPrep technique will greatly reduce the number of samples in which the specimen adequacy is compromised by inflammation. During 2002 the number of samples limited by inflammation at FAHC was 6.71% for conventional Pap smears compared to 1.17% for ThinPrep Pap tests.
Obscuring Mucus and/or Lubricant
To reduce the number of samples compromised by obscuring mucus or lubricant:
- removal of a visible mucus plug is recommended prior to the collection of an endocervical sample. (If utilizing the ThinPrep technique, do not place the mucus plug into the collection vial.)
- the use of lubricant on a speculum is not recommended when a cervical sample is to be collected.
Poor Preservation/Air Drying
With the conventional Pap smear, immediate preservation of the cellular sample with an alcohol-based fixative is essential. Incomplete fixation causes nuclear enlargement, which may result in false abnormal results. During 2002, 3.03% of conventional Pap smears were limited due to poor preservation. Utilization of the ThinPrep technique eliminates this problem.
To improve the preservation in conventional pap smears;
- Spray fix the sample immediately (within 5 seconds of smearing)
- Hold pump spray fix 6-12" from slide. (Aerosol fixative should not be held any closer that 12" from slide, holding closer will cause a "freezing" artifact)
- Cover the sample with fixative, generally 2-3 pump sprays (enough fixative to cover all areas of the slide, without washing the sample off the slide).
Absence of a Transformation Zone Component
Since most precancerous changes originate in the area of the transformation zone, it is very important to obtain an adequate sampling of cells from this area. In FDA clinical studies the endocervical brush and the Papette (broom) have been shown to be equivalent in regards to sampling the transformation zone (if used in accordance with the collection protocols. However, in women with a transformation zone high in the endocervical canal, the endocervical brush may produce a more satisfactory sample.
Insufficient Sampling of the Ectocervix
Most important, for any women with an intact cervix, both an endocervical and ectocervical sample must be collected. The FDA recommendation is to either use a single device, the Papette (broom) for simultaneous collection of an ecto and endocervical sample, or a combination of two separate devices, a spatula and an endocervical brush, to sample the ecto and endocervix separately. The combination of a Papette (broom) and an endocervical brush is not the recommended protocol. Use of both a Papette (broom) and endocervical brush may result in a sample, which is limited by obscuring blood.
* For ThinPrep samples, when a spatula is used, the FDA requires a plastic spatula.
Insufficient Cellular Sample
In general, cervical samples contain between 80,000 and 120,000 squamous epithelial cells. If a sample contains less than 10% of the expected number of cells, it is deemed unsatisfactory. Strict attention to collection techniques, utilizing the collection device(s) best suited for an individual patient's anatomy and following the recommended collection protocols may improve cell yield for both conventional and ThinPrep Pap tests.
