Critical values and diagnoses, with emphasis on cytopathology

CAP Today

January 2012
Cytopathology And More

Manon Auger, MD, FRCP(C)
Güliz A. Barkan, MD, FIAC

Although the concept of critical values is well established in the field of clinical laboratory medicine, the concept is relatively new and not as widely adopted and standardized in the field of anatomic pathology and cytopathology. A recent review article by Christopher N. Chapman, MD, and Christopher N. Otis, MD, addresses this important topic, giving a historical and evolutionary perspective of “critical values and diagnoses” in general as well as referring to the current regulations and future possibilities in surgical pathology and cytopathology (From critical values to critical diagnoses—a review with an emphasis on cytopathology. Cancer Cytopathol. 2011; 119:148–157). The article provides an important and timely viewpoint, especially today when there is a constant need to reduce medical errors in the health care system and improve patient safety.

The article first traces the development of the critical value concept, which is attributed to George D. Lundberg, MD, who published in 1972 an article titled “When to panic over abnormal values.”¹ The definition of critical value in this article is “...those laboratory values which reflect pathophysiologic derangements at such variance with normal as to be life-threatening if therapy is not instituted immediately.”¹ In this definition, three processes form the basis of the critical value concept: 1) detection of an abnormal important value, 2) effective communication of this value to the treating physician, and 3) prompt institution of therapy.

The Cancer Cytopathology article starts by providing an overview of critical values in the clinical laboratory where it most often corresponds to a numerical determination (for example, low blood glucose value) of a physiologic abnormality. Chapman and Otis then outline the evolution from “critical values” in the clinical laboratories to “critical diagnoses” in anatomic pathology. From being a purely time-sensitive value, the critical value becomes more an information-critical one, hence the preferred name of “critical diagnoses” in anatomic pathology, a conceptual difference introduced by Virginia LiVolsi, MD.² The article also summarizes the current requirements of CLIA ’88, the Joint Commission, and the CAP for laboratories in terms of having written procedures for reporting critical values/diagnoses.^3–5

The article refers to the few studies that have addressed critical diagnoses in the field of cytopathology. Although the list of what constitutes a critical diagnosis varies somewhat among the various publications, the most common circumstances for critical diagnoses include unexpected malignancies, the finding of organisms in nongynecologic specimens, and disagreement between the immediate and final interpretations in fine-needle aspiration specimens. The authors point out that although there is general agreement about notification within 24 hours on many critical diagnoses, there are some differences of opinion about other critical diagnoses (for example, notification is required as soon as possible, but not necessarily within 24 hours). They highlight the importance of the concept that the critical diagnoses policies should conform to each individual institution, evolving from open discussions between the pathologists and their clinical colleagues as to what constitutes “critical diagnoses” that both parties need to act on.

Finally, the authors raise many important questions related to critical diagnoses. Among them: What is a critical diagnosis versus an important diagnosis? What is the best method of clinician notification? To whom should the notification be delivered? How should the notification be documented in the cytopathology report? They also touch upon the role of the cytotechnologist in the critical diagnosis process. The article ends with a list of key elements that are instrumental in the operational success of a critical diagnosis policy in cytopathology. The most important are the creation and endorsement of a critical diagnosis list by laboratory personnel and key clinicians, a periodic review of the critical diagnosis policy with emphasis on correcting identified problems, and an increase in the relevance of the critical diagnosis policy by evaluating outcomes of patient care based on those diagnoses.

In summary, this article does not provide an exhaustive list of potential critical values/diagnoses. However, it is an excellent review of the evolution of critical values and diagnoses, the current regulations and requirements, and the issues and future directions. It can serve as a useful guide for those interested in implementing these important processes to improve patient safety.

References

1. Lundberg GD. When to panic over abnormal values. MLO Med Lab Obs. 1972;4: 47–54.
2. LiVolsi VA. Critical values in anatomic pathology: how do we communicate? Am J Clin Pathol. 2004;122:171–172.
3. Clinical Laboratory Improvement Amendments of 1988. Final rule (42 CFR Part 493.1109). Fed Regist. 1992;42:283.
4. Joint Commission on Accreditation of Healthcare Organizations. National Patient Safety Goals. Oakbrook Terrace, Ill.: Joint Commission on Accreditation of Healthcare Organizations; 2006.
5. College of American Pathologists. Laboratory Accreditation Program general and anatomic checklist items. GEN.41320, GEN.41330, GEN.41340, ANP.12175. Northfield, Ill., College of American Pathologists; June 17, 2010.

Dr. Auger, a member of the CAP Cytopathology Committee, is an associate professor in the Department of Pathology at McGill University, Montreal. Dr. Barkan, also a member of the committee, is an assistant professor of pathology at Loyola University, Chicago.