Stop Repeating Critical Values
A critical value is defined as an unexpected laboratory result that indicates a life threatening situation for the patient unless immediately acted upon. Therefore, the goal of the clinical laboratory is to report a critical value to a licensed caregiver as quickly as the result becomes available. The licensed caregiver must read-back the critical results to the medical laboratory scientist to prevent telephone communication errors and then call the physician. Both laboratory and nursing must document the date and times of all phone calls.
A recent Q-Probes study by the College of American Pathologists reported that 61% of clinical laboratories delay communication of critical values by as much as 20 minutes because they repeat the test to confirm the result before reporting (Lehman C, Howanitz P, Souers R et al. Arch Pathol Lab Med 2014; 138: 788-93).
In this study, 81 laboratories in the United States and 5 outside the U.S. submitted 40 initial and repeat critical value results for glucose, potassium, WBC count and platelet count. More than 99% of initial and repeat critical results were deemed to not be significantly different. These results confirmed the findings of a previous study which showed that repeat testing of critical hemoglobin, platelet count, WBC count, prothrombin time and activated partial thromboplastin time results did not offer any advantage over singlet testing (Toll, AD, et al. Arch Pathol Lab Med 2011;135:440-444).
Is repeat testing of critical values in a central clinical laboratory necessary? The answer is no! Even though critical values occur at the upper and lower ends of the analytical range, these results are just as reliable as normal results in a well-managed laboratory. Repeat testing may do more harm than good by delaying reporting of critical results.
