What Is A Rainbow Draw Lab

Abstract

Background

Collecting a predefined set of blood tubes (the "rainbow draw") is a common but controversial practice in many emergency departments (EDs), with limited data to support it. We determined the actual utilization of rainbow draw tubes at a single facility and evaluated the perceptions of ED staff regarding the utility of rainbow draws.

Methods

We analyzed 2 weeks of ED visits (1326 visits by 1240 unique patients) to determine blood tube utilization for initial and add-on testing, as well as the incidence of additional venipunctures. We also surveyed ED staff regarding aspects of ED phlebotomy and test ordering. Utilization data analysis was structured to satisfy specific concerns addressed in the ED staff survey.

Results

Observed tube utilization data showed that fluoride/oxalate, citrate, and serum separator tubes were frequently discarded unused, and that the actual utility of the rainbow draw for add-on testing and avoiding additional venipunctures was low. ED staff perceived that the rainbow draw was highly valuable, both to expedite add-on testing and to avoid additional venipunctures. Contrasting the objective (utilization data) and subjective (survey results) to drive changes in the standard ED blood collection reduced the estimated waste blood by 175 L/year.

Conclusions

Comparison of perceptions and objective utilization data drove process changes that were mutually agreeable to ED and laboratory staff. Although specifics of ED and laboratory work flows vary between institutions, the principles and strategy of this study are widely applicable.

Impact Statement

Emergency departments (EDs) and laboratories are challenged to maximize efficiency while maintaining optimal patient care. Rainbow draws (collecting a predefined set of blood tubes from all ED patients) are common, but little evidence is published that evaluates their utility. EDs often support use of rainbow draws to reduce turnaround time for laboratory testing and avoid additional venipunctures. Laboratories often argue against rainbow draws because of the wasted blood, materials, and staff time. This study addresses the utility of rainbow draws in 1 ED and highlights study design and process improvement factors that are likely to be applicable to any institution.

The practice of collecting extra blood tubes at the time of initial phlebotomy, often referred to as a "rainbow draw" (because of the various colors of tube stoppers) is a common but controversial procedure in many emergency departments (EDs)³. Proponents argue that rainbow draws facilitate rapid test performance and reduce need for additional venipunctures in the event of add-on testing. Critics point out the wasted blood, materials, staff time, and the potential for errors such as improperly labeled tubes (1).

Despite the controversy surrounding rainbow draws, there are few studies that examine their utility (1, 2). Studies often focus on efficiency (materials and time wasted) rather than impact to patients (e.g., additional venipunctures) or provider work flows (e.g., delays in laboratory test turnaround time). As a result, there is little published evidence to guide practice and even less that directly addresses clinical staff concerns or contains sufficient detail to allow comparison across institutions whose ED work flows might differ.

A common belief at our institution was that the rainbow draw was both necessary and useful. We sought to evaluate both the objective utilization and the subjective perception of the rainbow draw in our ED to foster a data-driven assessment of whether the practice accomplished the intended goal of minimizing waste while meeting clinical needs.

MATERIALS AND METHODS

This study was approved by the Mayo Clinic Institutional Review Board.

General work flows

ED work flow consisted of a triage nurse or physician placing orders based on symptom-specific protocols or clinical judgments, respectively; orders prompted phlebotomy personnel to collect the rainbow draw plus any other necessary specimens. Median time from order to collection typically ranges from 15 to 25 min in our ED. The standard rainbow draw included 2 serum tubes [5.0 mL of rapid serum (RST) and 8.5 mL of serum separator (SST)], 4.0 mL of EDTA whole blood for hematology, 2.7 mL of sodium citrate plasma for coagulation studies, and 4.0 mL of fluoride/oxalate plasma for lactate, for a total of 24.2 mL of blood per collection. All tube labels contained all necessary patient identifiers.

Tube utilization

Laboratory test orders were retrieved retrospectively from the laboratory information system and reviewed for all patients presenting to the ED from February 1 through 14, 2015.

Survey

We sent an e-mail link to an anonymous online survey regarding perceptions of the rainbow draw, add-on testing, and venipunctures to all ED physicians (n = 18) and nurses (n = 76); 19 individuals (20.2%) responded.

RESULTS

We extracted laboratory test details from a total of 1326 ED arrivals (average 95 patients/day) by 1240 unique patients. There were 878 venipunctures for rainbow draws (66.2% of ED visits).

Tube utilization and second venipunctures

We tallied tests according to the tube required and whether they were ordered before ("initial") or after ("add-on") venipuncture. All 5 rainbow draw tubes were required for testing in only 73 patients (8.3% of collections). Test counts for each tube type (Fig. 1) reflected almost 100% utilization of RST and EDTA tubes but incomplete utilization of SST (211 of 878; 24.0%), citrate (450 of 878; 51.2%), and fluoride/oxalate (256 of 878; 34.2%) tubes from the rainbow draw. It was not possible to determine retrospectively which serum tube was used for add-on testing; all serum add-ons were assigned to the SST unless no initial chemistries (always performed on the RST) were ordered. Add-on tests were ordered in 268 visits (30.5% of collections) and comprised 8.6% of tests performed on rainbow draw tubes (755 add-ons compared with 8028 initial tests). Most add-ons were for serum chemistries specific to the patient's presentation (e.g., liver function or thyroid tests) or additional coagulation studies beyond those initially ordered. Only 5% of citrate and fluoride/oxalate tubes were used solely for add-ons.

The utilization of each tube drawn in the rainbow is shown according to whether the tube was required for initial testing (blue) or the tube was unused until add-on tests were ordered (red).

Fig. 1.

The overlaid numbers provide the exact percentages for each category. Percentages that do not sum to 100% reflect unused tubes.

Fig. 1.

The utilization of each tube drawn in the rainbow is shown according to whether the tube was required for initial testing (blue) or the tube was unused until add-on tests were ordered (red).

The overlaid numbers provide the exact percentages for each category. Percentages that do not sum to 100% reflect unused tubes.

A total of 251 patients had add-on tests that could be performed using previously unused rainbow draw tubes; however, 71 of those patients required a second collection for other tests, so the rainbow draw did not avert a second venipuncture. The remaining 180 patients represent the maximum number of additional venipunctures potentially avoided by the rainbow draw. Most add-ons were for serum tests; these can generally be accommodated using the same tube as initial chemistries unless many add-on tests are ordered. Of the patients with only serum add-ons, most (n = 86) had ≤2 add-on tests ordered; 36 patients had >2 serum add-ons, which might have necessitated additional serum for testing. Another 58 patients had add-ons requiring plasma or whole blood. Combining the 36 patients with >2 serum add-ons and the 58 requiring nonserum tests, the estimated number of second venipunctures averted by the rainbow draw was 94, i.e., an average of 6.7 patients/day.

From the 878 rainbow draws, 15 RST, 20 EDTA, 667 SST, 575 fluoride/oxalate, and 428 citrate tubes were discarded unused. This averaged 10.6 mL of wasted blood per rainbow draw, or an annual estimated waste of >240 L of blood from unused tubes based on our annual (28000 visits) ED census at that time. Estimated material and labor costs per year for collecting and processing >45000 unused tubes were approximately $64000.

Staff perceptions

The ED staff survey demonstrated a high perceived value for the rainbow draw (Table 1). Staff overestimated how many patients required blood collections (78.9% of respondents selected ≥75%; actual was 66.2%) and how often all 5 tubes were used (94.7% of respondents chose >25%; actual was 8.3%). Although survey responses did accurately reflect the percentage of patients with add-on orders (actual was 30.5%), the number of add-on tests was substantially overestimated: 73.7% of respondents believed add-ons comprised ≥25% of test orders; actual was 8.6%. Finally, 78.9% of respondents believed that the rainbow draw averted a second venipuncture in >10 patients/day (including 36.8% who selected >20 patients/day), whereas the actual rate of averted venipunctures was approximately 7 patients/day.

Table 1.

Questions and responses in ED staff perception survey.^a

Questions asked	Answer options	Responses, % of respondents
What percentage of ED patients do you think have blood lab tests performed (i.e., a venipuncture in the ED is required)?	>90% of patients	31.6
	75%–90% of patients	47.4
	50%–74% of patients	21.1
	25%–49% of patients	0
	<25% of patients	0
For the ED patient encounters in which blood is drawn, how often do you think all 5 "rainbow draw" tubes are required to perform testing (both initial labs and add-ons)?	>90% of encounters	5.3
	75%–90% of encounters	31.6
	50%–74% of encounters	42.1
	25%–49% of encounters	15.8
	<25% of encounters	5.3
What percentage of blood tests do you think are add-ons, that is, ordered after initial blood collection in the ED?	>90% of tests	0
	75%–90% of tests	5.3
	50%–74% of tests	26.3
	25%–49% of tests	42.1
	<25% of tests	26.3
What percentage of patients who have blood collected do you think have add-on tests ordered during their ED encounter?	>90% of patients	0
	75%–90% of patients	5.3
	50%–74% of patients	26.3
	25%–49% of patients	42.1
	<25% of patients	26.3
On a typical winter day (about 90–100 patients), how many patients do you think have a second venipuncture while still in the ED?	0 patients	0
	1–2 patients	0
	3–5 patients	5.3
	6–10 patients	31.6
	11–15 patients	5.3
	16–20 patients	36.8
	>20 patients	21.1
On a typical winter day (about 90–100 patients), how many patients do you think avoid a second venipuncture because add-on tests can be done using the extra tubes drawn in the rainbow?	1 patient	0
	1–2 patients	5.3
	3–5 patients	5.3
	6–10 patients	10.5
	11–15 patients	21.1
	16–20 patients	21.1
	>20 patients	36.8

Questions asked	Answer options	Responses, % of respondents
What percentage of ED patients do you think have blood lab tests performed (i.e., a venipuncture in the ED is required)?	>90% of patients	31.6
	75%–90% of patients	47.4
	50%–74% of patients	21.1
	25%–49% of patients	0
	<25% of patients	0
For the ED patient encounters in which blood is drawn, how often do you think all 5 "rainbow draw" tubes are required to perform testing (both initial labs and add-ons)?	>90% of encounters	5.3
	75%–90% of encounters	31.6
	50%–74% of encounters	42.1
	25%–49% of encounters	15.8
	<25% of encounters	5.3
What percentage of blood tests do you think are add-ons, that is, ordered after initial blood collection in the ED?	>90% of tests	0
	75%–90% of tests	5.3
	50%–74% of tests	26.3
	25%–49% of tests	42.1
	<25% of tests	26.3
What percentage of patients who have blood collected do you think have add-on tests ordered during their ED encounter?	>90% of patients	0
	75%–90% of patients	5.3
	50%–74% of patients	26.3
	25%–49% of patients	42.1
	<25% of patients	26.3
On a typical winter day (about 90–100 patients), how many patients do you think have a second venipuncture while still in the ED?	0 patients	0
	1–2 patients	0
	3–5 patients	5.3
	6–10 patients	31.6
	11–15 patients	5.3
	16–20 patients	36.8
	>20 patients	21.1
On a typical winter day (about 90–100 patients), how many patients do you think avoid a second venipuncture because add-on tests can be done using the extra tubes drawn in the rainbow?	1 patient	0
	1–2 patients	5.3
	3–5 patients	5.3
	6–10 patients	10.5
	11–15 patients	21.1
	16–20 patients	21.1
	>20 patients	36.8

Boldface type denotes the answer option fitting the measured data (i.e., actual utilization rates).

Table 1.

Questions and responses in ED staff perception survey.^a

Questions asked	Answer options	Responses, % of respondents
What percentage of ED patients do you think have blood lab tests performed (i.e., a venipuncture in the ED is required)?	>90% of patients	31.6
	75%–90% of patients	47.4
	50%–74% of patients	21.1
	25%–49% of patients	0
	<25% of patients	0
For the ED patient encounters in which blood is drawn, how often do you think all 5 "rainbow draw" tubes are required to perform testing (both initial labs and add-ons)?	>90% of encounters	5.3
	75%–90% of encounters	31.6
	50%–74% of encounters	42.1
	25%–49% of encounters	15.8
	<25% of encounters	5.3
What percentage of blood tests do you think are add-ons, that is, ordered after initial blood collection in the ED?	>90% of tests	0
	75%–90% of tests	5.3
	50%–74% of tests	26.3
	25%–49% of tests	42.1
	<25% of tests	26.3
What percentage of patients who have blood collected do you think have add-on tests ordered during their ED encounter?	>90% of patients	0
	75%–90% of patients	5.3
	50%–74% of patients	26.3
	25%–49% of patients	42.1
	<25% of patients	26.3
On a typical winter day (about 90–100 patients), how many patients do you think have a second venipuncture while still in the ED?	0 patients	0
	1–2 patients	0
	3–5 patients	5.3
	6–10 patients	31.6
	11–15 patients	5.3
	16–20 patients	36.8
	>20 patients	21.1
On a typical winter day (about 90–100 patients), how many patients do you think avoid a second venipuncture because add-on tests can be done using the extra tubes drawn in the rainbow?	1 patient	0
	1–2 patients	5.3
	3–5 patients	5.3
	6–10 patients	10.5
	11–15 patients	21.1
	16–20 patients	21.1
	>20 patients	36.8

Questions asked	Answer options	Responses, % of respondents
What percentage of ED patients do you think have blood lab tests performed (i.e., a venipuncture in the ED is required)?	>90% of patients	31.6
	75%–90% of patients	47.4
	50%–74% of patients	21.1
	25%–49% of patients	0
	<25% of patients	0
For the ED patient encounters in which blood is drawn, how often do you think all 5 "rainbow draw" tubes are required to perform testing (both initial labs and add-ons)?	>90% of encounters	5.3
	75%–90% of encounters	31.6
	50%–74% of encounters	42.1
	25%–49% of encounters	15.8
	<25% of encounters	5.3
What percentage of blood tests do you think are add-ons, that is, ordered after initial blood collection in the ED?	>90% of tests	0
	75%–90% of tests	5.3
	50%–74% of tests	26.3
	25%–49% of tests	42.1
	<25% of tests	26.3
What percentage of patients who have blood collected do you think have add-on tests ordered during their ED encounter?	>90% of patients	0
	75%–90% of patients	5.3
	50%–74% of patients	26.3
	25%–49% of patients	42.1
	<25% of patients	26.3
On a typical winter day (about 90–100 patients), how many patients do you think have a second venipuncture while still in the ED?	0 patients	0
	1–2 patients	0
	3–5 patients	5.3
	6–10 patients	31.6
	11–15 patients	5.3
	16–20 patients	36.8
	>20 patients	21.1
On a typical winter day (about 90–100 patients), how many patients do you think avoid a second venipuncture because add-on tests can be done using the extra tubes drawn in the rainbow?	1 patient	0
	1–2 patients	5.3
	3–5 patients	5.3
	6–10 patients	10.5
	11–15 patients	21.1
	16–20 patients	21.1
	>20 patients	36.8

Boldface type denotes the answer option fitting the measured data (i.e., actual utilization rates).

DISCUSSION

EDs are high-pressure environments in which care must be not only accurate but also efficient. Many EDs are in a near-constant state of process improvement to increase patient throughput (3–5); per-visit improvements of even 6 min are considered worthy of publication (6). In such an environment, ED personnel often subscribe to process improvement philosophies that place a premium on time efficiencies.

Laboratory personnel, however, often use process improvement philosophies that emphasize reducing waste. The risk of iatrogenic anemia and other patient safety concerns related to excessive phlebotomy drive laboratories to reduce blood volumes collected, particularly in hospital settings where repeat collections are common. In addition, the cost of "extra" tubes includes materials plus staff time to collect, process, store, and retrieve samples that might never be used.

Although the survey response rate was low (20.2%), it was consistent with online survey response rates for healthcare professionals (7). In addition, the results aligned with anecdotal impressions of both ED and laboratory staff: It was generally understood that the ED reliance on add-on testing necessitated use of the rainbow draw and saved patients unnecessary additional venipunctures.

Although ED staff perceived the rainbow draw as important, utilization data suggested that a full rainbow draw for every patient led to significant waste. We used this discordance between perceived value and actual utilization to drive change: Extra citrate and fluoride/oxalate collections were eliminated, and the SST was reduced to a 3.5-mL tube. Occasionally extra tubes are drawn in select scenarios (e.g., stroke protocol), but currently <5% of citrate and fluoride/oxalate tubes are discarded unused. The SST was retained because of the frequent need to send serum for testing outside of the hospital laboratory and the inability to add tests onto the RST until initial testing is completed. Anecdotally, ED staff did not perceive these changes as disruptive to their work flow.

These changes decreased the estimated blood waste to 2.8 mL/collection, which projects to a decreased waste of approximately 65 L/year. Subsequent reviews of ED collections demonstrated no increase in second venipunctures because of these changes, despite the data suggesting that some citrate and fluoride/oxalate tubes were being used solely for add-ons. We believe this likely reflects concurrent implementation of an electronic solution addressing the most common fluoride/oxalate add-ons (lactate added during sepsis evaluation) and might also reflect changes in ordering practices.

Although ED and laboratory work flows vary between institutions, the strategy of incorporating both objective (tube/test counts) and subjective (staff perception) factors into the evaluation of process efficiency is applicable to other institutions. We believe that ensuring the objective study was sufficiently detailed to address all subjective concerns was a key factor in this project—a simple count of unused tubes would not have addressed ED staff perceptions regarding second venipunctures, for example. Other generally applicable factors driving successful translation of this study into meaningful improvement included willingness of both the ED and laboratory to compromise (eliminating some but not all extra tubes) and doing adequate follow-up to ensure changes did not result in negative outcomes (e.g., additional venipunctures).

3 Nonstandard abbreviations

Author Contributions: All authors confirmed they have contributed to the intellectual content of this paper and have met the following 4 requirements: (a) significant contributions to the conception and design, acquisition of data, or analysis and interpretation of data; (b) drafting or revising the article for intellectual content; (c) final approval of the published article; and (d) agreement to be accountable for all aspects of the article thus ensuring that questions related to the accuracy or integrity of any part of the article are appropriately investigated and resolved.

Authors' Disclosures or Potential Conflicts of Interest: No authors declared any potential conflicts of interest.

Role of Sponsor: No sponsor was declared.

References

Seaver

Gray

Drawing extra blood tubes in the ED: re-examining a common practice

(Accessed June 2018).

Sanders

Karr

Improving ED specimen TAT using Lean Six Sigma

Int J Health Care Qual Assur

2015

;

428

–

Takakuwa

Shofer

Abbuhl

Strategies for dealing with emergency department overcrowding: a one-year study on how bedside registration affects patient throughput times

J Emerg Med

2007

;

337

–

O'Brien

Williams

Blondell

Jelinek

Impact of streaming "fast track" emergency department patients

Aust Health Rev

2006

;

525

–

Traub

Wood

Kelley

Nestler

Chang

Saghafian

Lipinski

Emergency department rapid medical assessment: overall effect and mechanistic considerations

J Emerg Med

2015

;

620

–

Soremekun

Biddinger

White

Sinclair

Chang

Carignan

Brown

Operational and financial impact of physician screening in the ED

Am J Emerg Med

2012

;

532

–

Cho

Johnson

VanGeest

Enhancing surveys of health care professionals: a meta-analysis of techniques to improve response

Eval Health Prof

2013

;

382

–

407

Author notes

This manuscript represents original work that has not been previously reported. A subset of the information was presented in a webinar in November 2016.