The Negligent Interpretation Of Pap Smears
Published by the American Society of Cytopathology in their Journal, Pathology Patterns Reviews.
Cervical cancer continues to kill approximately 4900 women annually. This is a particularly alarming statistic to the 15,700 women who are annually diagnosed with new cases of cervical cancer.
Though there are a variety of diagnostic errors which occur due to negligence in the processing and interpretation of Pap smears some misinterpretations are unavoidable. Assume that a gynecologist properly obtains a Pap smear that is then properly applied to a slide and fixed. Though the patient, at the time is suffering from a pre-invasive lesion of the cervix, so few abnormal cells are present in the smear that they are unlikely to be located during a careful screening of the slide. The delay in diagnosis that results from this unrevealing smear is unavoidable and undoubtedly occurs. However, in the author’s experience the patient presenting with advanced cervical cancer, following serial purportedly benign annual Pap smears has been the victim of professional carelessness. Review of slides, in such cases, reveals inadequate smears which were not reported, abnormal cells that were either identified but then ignored by the physician performing the Pap smear or were misinterpreted or not located by the cytopathologist or cytotechnologist examining the smear.
The devastation that results from a needlessly advanced case of cervical cancer, a disease, which most believe is largely preventable, is tragic. It is the obligation of the lawyer representing claimants in such cases to obtain through the legal system what compensation is there available. However, the legal process also can reveal the causes of a client’s injuries and properly identify those persons responsible. Ideally, the process of litigation should inform those persons responsible of their errors and encourage them and others to act more responsibly in the future.
Each year many women diagnosed with cervical cancer, or their significant survivors consult lawyers to determine whether the stage of the cervical cancer at the time of diagnosis and the related morbidity and mortality could and should have been avoided. According to Dr. Scott, examining pathology claims at one insurance carrier corresponding to the period of July 1, 1993 to August 10, 1995, 17% of the claims involved Pap smear interpretations as the central issue. The dollar value of the claims was estimated to represent 25% of all new pathology claims during the measured interval. Though an examination of the claims for any interval of any given insurance carrier is not necessarily reflective of national or regional trends, there is no question that it is the common experience of knowledgeable physicians and lawyers that Pap smear cases represent significant liability exposure for health care providers.
The number of claims made involving Pap smears represents, at best, a very small percentage of the total number of false-negative cases which have, in fact, resulted in needless delays in diagnosis and treatment and resultant excess morbidity. This is obvious when one considers that the false-negative rate of a single Pap smear is widely quoted to be 20%. . Some maintain that more recent data actually indicate the sensitivity of a single Pap smear in women undergoing routine screening may be closer to 50%.
Koss has asserted that invasive cancer is rarely preceded by truly negative serial Pap smears when available for the 2 to 3 years prior to the diagnosis of invasive cancer being made. My experience is consistent with that of Dr. Koss.
In 1987, Van der Graaf, Y., et al., reported striking findings concerning screening errors in cervical cytoloty. In a screened population of 165,185 women, 555 women demonstrated “moderate dysplasia” or a higher lesion, three years after a negative screening. An examination of the slides previously read as negative showed that the adequate smears all were misread. Fully 1/3 represented “dysplasia” or a carcinoma in situ. According to Dr. Koss, in those cases contained in the literature where prior negative smears of patient with invasive cancer are examined, cancer cells are apparent on review.
In 1961, at a time when few American women were being screened, the incidence of cervical cancer was 33 per 100,000. By 1987, when the population of women screened at some time during their lives reached 80%, the incidence of squamous cell carcinoma of the cervix dropped to 8.3 per 100,000. The rate of cervical cancer, in countries where screening does not occur, continues at the same rate as that of industrialized countries before the initiation of large-scale screening programs. It is obvious that screening programs have greatly reduced the incidence of the disease. However, the continued occurrence of cervical cancer in the screened population suggests that inadequate screening occurs or that the screening process is inherently incapable of identifying a significant percentage of women with disease prior to the occurrence of invasive cervical cancer. It is this author’s position that the occurrence of 8.3 cases per 100,00 is due to inadequacies in the screening process. That inadequacies exist is well borne out by the literature. It is these inadequacies which are the subject of this paper.
Can Advanced Cancer and Deaths be Prevented by Pap Smears?
The object of reducing the occurrence of false-negative Pap smears has been a major focus of legislative reform and of ongoing quality control programs throughout the country. Whether the 4900 annual excess deaths from cervical cancer are subject to further reduction has been questioned by some authors recently. Frabel and others focus primarily on the perceived plight of the cytotechnologist, cytopathologist or laboratory, or the assumed increased cost which would result from any significant improvement to the existing system. , DeMay argues that cytologists are being held to an impossible standard of perfection in malpractice litigation and that a zero error standard is both unreasonable and impossible to achieve in practice. The legal system does not demand perfection. The legal system does demand that cytotechnologists and cytopathologists perform in conformity with those principles of practice about which there is uniform agreement. From a legal perspective, a zero error standard is reasonable, whether or not it is possible to achieve in practice. All standards of practice must be at least theoretically obtainable. If it were theoretically impossible to perform in a certain manner in practice, such performance would not be a standard to which any professional would be held. We do not ignore in our culture the incidence of carelessness simply because it is supposed that human beings will, on occasion, be careless.
The cytopathologist can have a far-reaching role in reducing morbidity due to cervical cancer. This role is not limited to interpreting properly Pap smears submitted for review. The cytopathologist also has a responsibility to inform those submitting smears of the adequacy of the smears and to submit reports in a comprehensive and comprehensible form, together with recommendations for future management (diagnostic evaluation).