Clinical laboratories often receive extra blood tubes beyond what is needed for associated laboratory test orders. Sometimes, this practice involves drawing tubes of every possible color (the “rainbow”) to allow for add-on testing at a later time. Despite the widespread use of extra tubes, we found virtually no peer-reviewed literature on this practice.1 There has been more focus on phlebotomy draw volumes2-4 and iatrogenic anemia from repeated laboratory testing.5 We performed a retrospective study analyzing extra blood tube usage over 6 years at the University of Iowa Hospitals and Clinics (UIHC) to examine how often extra tubes were used for add-on orders.

Methods

The study had institutional review board approval from the University of Iowa and included data from May 2, 2009, to June 15, 2015. The UIHC uses Epic (Epic Inc) as the electronic medical record (EMR) and for computerized order entry of laboratory testing. Data were extracted using Reporting Workbench and Healthcare Enterprise Decision Intelligence reports within Epic, using specimen accession numbers to explicitly link extra tubes with add-on testing.6

Results

During the retrospective time period, 370 601 extra blood tubes were collected, with the emergency department (ED), outpatient clinics, and inpatient units accounting for 23.7%, 30.2%, and 46.1% of total extra tubes, respectively. The maximum for an individual patient was 165 extra blood tubes; 572 additional patients had 50 or more extra blood tubes each.

Overall, only 7.0% of extra tubes were used for add-on testing. The percentage was highest for the inpatient units (11.5%) and lowest for the ED (2.8%). Figure 1 shows a breakdown of total extra blood tubes (subdivided into tube types) and the fraction ultimately used for add-on testing. Add-on testing for extra tubes was highest for K 2 -EDTA tubes (commonly used for hematology tests) and lithium-heparin plasma separator tubes (for clinical chemistry tests). Extra serum tubes were used for add-ons in less than 0.4% of cases for the ED, outpatient clinics, and inpatient units.

Multiple changes occurred that were temporally followed by decreases in extra tubes (Figure 2A). For inpatient units and the ED, there was a switch over time to paperless specimen labeling, whereby specimen labels printed only if required for ordered testing. This replaced the previous process that used hardcopy patient requisitions and generic patient identification labels.6 In this new system, extra tubes required an additional electronic order to generate a specimen label. For the outpatient areas, data analysis showed 2 clinics with very high extra tube usage. Collaboration between the laboratory and the nursing and medical leadership of those 2 clinics was followed by a drop in extra tube usage that almost entirely accounts for the overall decrease in outpatient extra tubes from 2013 to 2015. Patient encounters (inpatient, outpatient, and ED) and laboratory test activity all were steady or increasing during the retrospective time period, indicating the drop in extra tubes was not due to lower patient volumes (Figure 2B).

Discussion

Our study shows that extra blood tubes were used for add-on testing at a low rate (7.0%). The rate was especially low for serum tubes (< 4 in 1000). Excessive use of extra tubes may contribute to iatrogenic anemia, patient discomfort, and risk of biohazard exposure. Extra tubes also consume phlebotomy and laboratory resources in the collection, processing, and disposal of specimens. Ongoing education and changes in the EMR may help address the use of extra tubes. At our institution, electronic order sets underwent extensive review and specify extra tube collection only for situations or protocols likely to need these tubes for add-on orders. Future studies are needed to understand the clinical situations under which extra tube collection is most appropriate.

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Corresponding Author: Matthew D. Krasowski, MD, PhD, Department of Pathology, University of Iowa Hospitals and Clinics, 200 Hawkins Dr, Ste C-671 GH, Iowa City, IA 52242 (mkrasows@healthcare.uiowa.edu).

Published Online: November 7, 2016. doi:10.1001/jamainternmed.2016.6834

Author Contributions: Dr Krasowski had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Concept and design: Humble, Krasowski.

Acquisition, analysis, or interpretation of data: All authors.

Drafting of the manuscript: All authors.

Critical revision of the manuscript for important intellectual content: Humble, Krasowski.

Statistical analysis: Humble, Krasowski.

Administrative, technical, or material support: Hounkponou, Krasowski.

Study supervision: Krasowski.

Conflict of Interest Disclosures: Dr Krasowski has served as the principal investigator for clinical trials for Roche Diagnostics and Radiometer Inc. No other disclosures are reported.

Additional Contributions: We thank Nitin Karandikar, MD, PhD, and Nancy Rosenthal, MD (Department of Pathology, University of Iowa Hospitals and Clinics, Iowa City), for critically reviewing the manuscript. We also thank Jodi L. Felderman (Department of Finance and Accounting Services, University of Iowa Hospitals and Clinics, Iowa City, Iowa) for extracting data for inpatient discharges, inpatient days, outpatient discharges, and emergency department visits for the University of Iowa Hospitals and Clinics and affiliated facilities. None of these individuals received compensation.