The policy of storing clinical samples in a pathology laboratory is based on long-standing practice rather than on objective data regarding the actual use of the stored samples.
To determine the time after initial order that requests for add-on tests are submitted to the laboratory. These data might be useful for improving the efficiency of sample storage.
Two hundred sixteen add-on requests evenly divided between inpatients and private practice patients were reviewed for types of tests added on and the time of the requests.
Ninety-five percent of add-on test requests for inpatients were made by 0.75 day after the initial order (range, 0.01-4.3 days). However, the 95th percentile for private practice patients' add-on requests did not occur until 5.6 days later (range, 0.01-7.0 days). The pattern of add-on tests for hospitalized patients also differed from those for private practice patients. Most add-on tests for hospitalized patients were for routine hospital tests, and the private practice add-on requests were for assays that were not as routine, frequently for testing referred to the reference laboratory. This difference affected the rapidity of completing the add-on tests.
Samples for hospitalized patients can be stored for 3 days, but samples from patients in private practices should be held for 7 days. This change of "usual" storage practice would increase the efficient use of laboratory space and personnel. Screening all requests for add-on tests for hospitalized patients might reduce the frequency of unnecessary add-on requests, further increasing the efficiency of the laboratory.