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Quality and liability issues with the Papanicolaou smear: the problem of definition of errors and false-negative
1Department of Pathology and Laboratory Medicine, University of Kentucky Medical Center, Lexington 40536-0093, USA.
Abstract:
A universally accepted definition for a false-negative Papanicolaou smear has not been established. Therefore, it is important to specify the criteria used to define false-negative smears when discussing the performance of clinical cytology. If these variables are not specified, there is potential for miscommunication. Variables include sampling versus laboratory false-negative errors, the definitions of what constitutes disease and the threshold to define an error, the time interval to detection, and the mechanism for detection of errors. False-negative error rate is defined as the number of false-negative Papanicolaou smears divided by the number of patients with disease. Discrepancy rate is often used interchangeably with false-negative rate, but the former does not factor in the prevalence of disease and the threshold used to define an error. The false-negative fraction is most useful for interlaboratory comparison. A reasonable definition of a laboratory false negative is a smear originally reported as negative or normal that is found to have sufficient numbers of carcinoma or dysplastic cells on review. The abnormal cells should be verifiable by more than one experienced cytologist in a blinded fashion, and it is ideal if the lesion is confirmed by biopsy or other confirmatory test.
Insights
Defining false-negative Papanicolaou smears is crucial for accurate clinical cytology. Clear criteria prevent miscommunication regarding Papanicolaou smear errors and disease detection.
Area of Science:
- Cytopathology
- Gynecologic Oncology
Background:
- A universally accepted definition for a false-negative Papanicolaou smear is lacking.
- This absence of a standard definition can lead to miscommunication in clinical cytology.
- Key variables influencing false-negative definitions include error type, disease criteria, detection intervals, and error detection mechanisms.
Purpose of the Study:
- To highlight the importance of establishing clear criteria for defining false-negative Papanicolaou smears.
- To discuss the variables that need specification when reporting Papanicolaou smear performance.
- To differentiate between related metrics like false-negative rate, discrepancy rate, and false-negative fraction.
Main Methods:
- Review of existing literature and definitions related to Papanicolaou smear errors.
- Analysis of variables contributing to the definition of false-negative smears.
- Proposal of a reasonable definition for laboratory false-negative Papanicolaou smears.
Main Results:
- The false-negative error rate is calculated as the number of false-negative Papanicolaou smears divided by the number of patients with disease.
- Discrepancy rate is distinct from the false-negative rate as it does not account for disease prevalence or error thresholds.
- The false-negative fraction is most valuable for interlaboratory comparisons.
Conclusions:
- A proposed definition for a laboratory false-negative Papanicolaou smear involves a negative or normal initial report with subsequent identification of sufficient abnormal cells upon review.
- Verification of abnormal cells by multiple experienced, blinded cytologists is recommended.
- Confirmation of the lesion by biopsy or other confirmatory tests is considered ideal for validating a false-negative finding.
