Diagnostic Cytology
Table 6.1
The 2001 Bethesda System—cont'd
provide a brief description of the test method(s) and report result so that it is easily understood by the clinician.
au to m ated review
If case is examined by automated device, specify device and result.
educ atio nal notes a n d suggestions (o ptio n al)
Suggestions should be concise and consistent with follow-up guidelines published by professional organizations (references to
relevant publications may be included).
or malignancy, the presence of endometrial cells in a women 40
years or older, or the presence of organisms, can be reported in
this context, since this information may prove to be clinically
relevant for patient management.
As in prior Bethesda adequacy guidelines, if abnormal
cells are detected, the specimen cannot be categorized as
Squamous Cellularity
TBS 1991 required that well-preserved and well-visualized squa-
mous epithelial cells should cover more than 10% of the slide
surface. In order to address adequacy on conventional as well as
liquid-based preparations, and to improve interobserver repro-
ducibility, TBS 2001 went further to provide numerical estimates
of what constitutes adequacy for squamous cellularity in cervi-
cal cytology preparations.
Conventional smears:
An adequate conventional prepa-
ration should have a minimum of approximately
8,000-12,000 well-preserved and well-visualized
squamous cells. This minimum cell count should
not counted. The count includes both
nucleated mature and metaplastic squamous cells. The
percentage of hypocellular areas, if present, should be
estimated and the fields counted should reflect this
proportion. The Bethesda atlas10 and website11 provide
"reference images" of known cellularity at low (4x)
magnification as a resource for cytologists to compare
with the specimen being assessed.
Liquid-based preparations
(LBP): An adequate LBP
should have an estimated minimum of at least 5,000
well-visualized, well-preserved squamous cells.10,17
Estimation of cellularity is suggested in borderline
cases by performing representative field counts.
A minimum of 10 fields, usually at 40x, are assessed
along a diameter that includes the center of the
preparation. The average number of squamous cells
per field is thus estimated. One preliminary study
suggested that LBPs containing 5,000-20,000
squamous cells should be considered as "borderline"
The reader is referred to the Bethesda atlas for cellularity
tables and figures.10 These guidelines may change in the future
based on additional data.
The TBS numeric criteria for cellularity may not be appli-
cable to vaginal specimens, cases with extensive cytolysis, cell
clustering, and some cases of atrophy. Cytologists should utilize
clinical information and their best judgment when interpreting
such cases. At present there are no published studies specifically
addressing the relationship between low cellularity and false-
negative rate.
Quality indicators
Patient/Specimen identification and Technical
Correct specimen identification is essential for evaluation and is
required by the Clinical Laboratory Improvement Amendments
of 1988 (CLIA '88). In addition to ensuring that the specimen
corresponds to the correct patient, proper identification allows
the laboratory to locate prior records and slides from the patient
that may influence the current evaluation.
The cellular material must be well fixed and unobscured
for interpretation. Minimal data regarding how obscuring
factors affect the interpretive reliability of a cervical speci-
men are available. In order to be considered obscuring, the
morphology must be uninterpretable.
example, although most cervical samples contain inflamma-
tory cells, moderate numbers do not generally obscure the
nuclei of squamous cells. Even a large amount of inflamma-
tion or blood may be acceptable if it is spread thinly such
that the intermixed epithelial cells can be easily visualized.
In general, specimens with more than 75% of epithelial cells
obscured are considered unsatisfactory. A variety of factors
may compromise visualization of the cells. Heavy inflamma-
tion, blood, and extensive cytolysis are patient-related and
independent of the sample taker. However, presence of air-
drying, thick uneven smears, or lubricant is often inversely
correlated with the skill and experience of the clinician.
With liquid-based preparations a number of these factors
become less significant; however, appropriate collection/rins-
ing techniques need to be utilized. Clinicians who repeatedly
obtain technically poor quality specimens may benefit from
constructive feedback provided in the written report, by tel-
ephone, or in a summary format comparing adequacy rates of
peer group clinicians.
Clinical information
Providing pertinent clinical information may increase the
sensitivity and reliability of the evaluation by directing atten-
tion to a clinical question or by clarifying otherwise uncertain
cytologic findings. At a minimum, age and date of last men-
strual period should be provided. Absence of this informa-
tion does not, however, preclude evaluation; therefore, the
specimen may remain categorized as "satisfactory" in these
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