Female Genital Tract
The Bethesda System for Reporting
Cervical Cytology
Ritu Nayar, David C Wilbur and Diane Solomon
T h e B e th e sd a S y ste m : H isto ric a l P e rs p e c tiv e
E p ith e lia l C e ll A b n o r m a lit ie s : S q u a m o u s C e ll
T h e 2 0 0 1 B e th e s d a S y s te m
E p ith e lia l C e ll A b n o r m a lit ie s : G la n d u la r C e ll
R e p o rt F o rm a t
E d u c a tio n a l N o te s / S u g g e s tio n s
S p e c im e n A d e q u a c y
A n c illa ry T e s tin g
B e th e s d a 2 0 0 1 S p e c im e n A d e q u a c y C a t e g o r ie s
A u to m a te d R e v ie w
S q u a m o u s C e llu la r it y
In te ro b se rv e r R e p r o d u c ib ility in C e rv ic a l C y t o lo g y
Q u a lit y I n d ic a to r s
M a n a g e m e n t G u id e lin e s
Im p a c t o n L a b o r a to r y p ra c tic e
C o n c lu d in g R e m a rk s
G e n e ra l C a te g o riz a tio n
In te rp re ta tio n / R e su lt
N e g a tiv e f o r I n t r a e p ith e lia l L e s io n o r M a lig n a n c y ( N IL M )
E n d o m e t r ia l C e lls
The Bethesda System: Historical
Terminology forms the basis for effective communication
between the laboratory and clinician. The clinician is expected
to provide relevant patient information to the laboratory. It is
the laboratory's responsibility to report results using terminol-
ogy that clearly conveys the diagnostic interpretation of the mor-
phologic findings. The use of a uniform diagnostic terminology
facilitates communication by establishing a common language
that, in theory, does not vary significantly from cytologist to
cytologist or laboratory to laboratory. However, terminology is
not static over time; rather, it evolves in parallel with increased
understanding of the pathogenesis and biology of disease. The
framework, therefore, must be flexible enough to incorporate
advances in scientific knowledge without creating undue confu-
sion or complexity.
In 1988, the National Cancer Institute sponsored an open
cians, and representatives of professional organizations—to
develop a uniform descriptive terminology for cervical/vagi-
nal cytologic interpretation. The format that emerged became
known as
The Bethesda System
Approximately two years later, a second meeting was con-
vened to critique and refine the terminology based on experience
with the use of the system in actual laboratory practice. Minor
modifications were incorporated into the 1991 Bethesda System
that streamlined the terminology.2 In addition, an ad hoc com-
mittee developed criteria for specimen adequacy and Bethesda
interpretive categories, culminating in the first TBS atlas that
outlined and illustrated the morphologic features.3 By the mid-
to late 1990s, there was a significant penetration of the Bethesda
System into cytopathology practice with approximately 90% of
laboratories in the United States using the Bethesda terminol-
ogy for reporting of cervical/vaginal cytology.4
Among all the changes introduced by the implementation
of TBS terminology into practice, none was more controversial
than the category of atypical squamous cells (ASCUS). At that
time, the majority of abnormal Pap tests reported annually in
the United States, approximately 2.5 million, were interpreted
as ASCUS and had highly variable management at considerable
cost to the healthcare system. Another 1.2 million were inter-
preted as low-grade squamous intraepithelial lesion (LSIL).5 In
an effort to determine the best management strategy (effective
as well as cost-effective) for women with these equivocal and
low-grade abnormalities, the National Cancer Institute (NCI)
sponsored the ASCUS/LSIL Triage Study (ALTS), which was
completed in 2001.6 This study, as detailed below, has allowed
for a data-driven approach to management of these prevalent
cervical cytologic abnormalities.
From its inception, the fundamental aim of the Bethesda
System has been to communicate clinically relevant information
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