PA PSRS Patient Saf Advis 2007 Jun;4(2):64-6.
In Vitro Hemolysis: Delays May Pose Safety Issues
Nursing; Pathology
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Appropriate specimens are required for accurate and precise laboratory results that facilitate good patient care. When specimens are inappropriate, they must be rejected and the specimen must be redrawn.1 Jones et al. studied the rate of rejection of chemistry and hematology patient specimens and found the most frequently cited reason for specimen rejection in chemistry was hemolysis, which occurred five times more frequently than the next reason, insufficient specimen quantity.2

Hemolysis occurs when there is a break in a red blood cell’s membrane, which causes the release of hemoglobin and other internal components to leak into the surrounding fluid.3 The cell breakdown is often evident to the naked eye in a pink to red tinge in the serum or plasma. As of December 2006, PA-PSRS received more than 550 reports regarding specimens that were grossly hemolyzed. Of those reports, more than 50% (312) were specimens collected in the emergency department (ED).

Hemolyzed specimens present a patient safety concern because hemolysis may cause certain analytes (e.g., potassium) to increase due to leakage from broken red blood cells.3 Laboratories reject hemolyzed specimens for analysis, rather than rendering an inaccurate result from such specimens that could result in an error in patient care. However, rejecting the specimen has its own safety implications because the patient has to sustain another invasive test, and the process of redrawing the specimen may delay patient diagnosis and treatment.1 While reducing the number of hemolyzed specimens may yield some cost saving benefit related to an overall lower number of blood draws, there are also significant quality and safety benefits, which include a reduced number of needle sticks per patient; improved turnaround times for patient specimens; and increased satisfaction among physicians, nurses, and patients.4

Hemolysis can occur from two sources: in vivo hemolysis, which is primarily due to pathological conditions such as autoimmune hemolytic anemia or a transfusion reaction; and in vitro hemolysis, which may be due to improper specimen collection, specimen processing, or specimen transport.3 In vivo hemolysis, which may have as many as 50 clinical causes, is beyond the scope of this article. However, in vitro hemolysis can be controlled by monitoring the process in which the blood samples are drawn and treated.5 This article will focus on the causes of in vitro hemolysis and highlight some recommended corrective action steps to monitor and improve the process.

PA-PSRS Reports

The reports submitted to PA-PSRS of hemolyzed specimens originating in the ED (see above) illustrate the potential for hemolyzed specimens to cause patient harm. For example, lack of timely reporting may cause delays in treatment. In some cases, patients may leave against medical advice or be transferred before another specimen can be obtained. While patients and physicians wait for results, ED overcrowding can occur and patient satisfaction decreases. The following reports submitted to PA-PSRS illustrate some of these scenarios:

Specimen grossly hemolyzed; called to recollect specimen. About an hour later, emergency room called for results. Doctor called lab and wanted hemolyzed specimen run. Ran and reported.

Grossly hemolyzed specimen; patient transferred before specimen recollected. The test was canceled.

Causes of In Vitro Hemolysis

The causes of in vitro hemolysis may include one or a combination of the following:3,6

  • Poor selection of venipuncture site
  • Inadequate preparation of venipuncture site
  • Extended tourniquet application and time
  • Improper venipuncture technique
  • Vigorous tube mixing
  • Errors in specimen transport and processing

Risk Reduction Strategies

Addressing the following issues can help ensure that a quality specimen is obtained for analysis.

Site Selection

Choosing an optimal venipuncture site is essential to obtaining a quality sample. The preferred site is the median cubital vein, because this vein is usually the easiest to access; this means less trauma to the patient from probing to find the vein.6 Drawing from a site distal to the antecubital region of the arm, rather than drawing from an antecubital site, may result in greater incidence of hemolysis.3

Site Preparation

Allow sufficient drying time when using alcohol to clean the site.3 Cleansing the venipuncture site with alcohol and not allowing the site to air dry may cause the alcohol to contaminate the specimen and cause hemolysis.6,7

Tourniquet Application and Time

Limiting the time a tourniquet is used may prevent hemolysis. Prolonged tourniquet time can lead to an increase in various chemistry analytes, including serum protein, potassium, and lactic acid due to hemoconcentration of blood at the puncture site.6   Avoid tourniquet use in excess of one minute, as well as excessive fist clenching by the patient.3,8 Repeated fist clenching with or without tourniquet may cause excessive release of potassium from skeletal muscles (pseudohyperkalemia), which may lead to an inaccurate reporting of the results.9

A good rule of thumb to determine the one-minute tourniquet time is to remove the tourniquet when blood starts to flow into the first tube of blood being drawn.6  Be sure that the tourniquet is visible as a reminder that it must be removed after the blood specimen has been drawn.

Drawing Technique

Proper drawing technique avoids coming too close to the vein wall. An improper venipuncture, evidenced by a slower than normal blood flow, may indicate occlusion due to the lumen of the needle being too close to the inner wall of the vein, causing hemolysis.10 Excessive probing to find a vein can result in a poor quality sample, including hemolysis.6

Select the right size needle. A needle bore that is too small can lead to a large vacuum force applied to the blood, and may cause stress on the red blood cells, causing them to rupture. A needle bore that is too large may result in a much faster and more forceful flow of blood through the needle, resulting in hemolysis.3,5

Handle the syringe plunger with care. Hemolysis may result from pulling the plunger of a syringe back too hard, generating too much negative pressure, while using a large-bore needle.5 To avoid needlestick injury, after the blood is collected by syringe, consider the use of a shielded transfer device to complete the transfer.11 If such a device is unavailable when filling the specimen tube, the positive pressure behind the plunger that forces the blood through the needle combined with the vacuum force in the tube may result in hemolysis or may cause the stopper of the tube to pop off.3

Check the tubing connection when taking specimens from intravenous catheters. Several studies have noted that when blood is drawn from a peripheral IV catheter, a higher incidence of hemolysis occurs due to frothing of the blood from a loose connection of the blood collection assemblies.3

Tube Mixing

All tubes with additives need to be inverted gently a number of times to mix the additive evenly with the blood.6 Avoid vigorous mixing or shaking of a specimen because the red blood cells may break and leak intracellular contents. Because the concentration of potassium in the red blood cells is nearly
23 times the level in plasma, prolonged contact between the red blood cells and the serum fraction may cause artificial elevations in the serum potassium level.9

Specimen Transport and Processing

Mechanical trauma during transport may occur with the use of a pneumatic tube system, resulting in hemolysis. Variable factors are related to system differences such as length, speed, and number of times the specimen is transported, as well as the number of angles or turns the system uses.4

Monitor specimen temperature. Excessive heat or cold can also cause the red blood cells to rupture.3

Allow for proper clotting time. Not allowing the serum specimen to clot for the recommended amount of time can result in fibrin formation in the serum. The use of applicator sticks to dislodge the fibrin may cause rupture of the red blood cells, resulting in hemolysis.3

Is There an Opportunity for Improvement at Your Facility?

Reports of hemolyzed specimens submitted to PA-PSRS indicate an opportunity for process improvement. Consider the following steps to determine if a problem exists within your facility:

  1. Analyze the reasons for redraw requests. In many cases, the greatest number of redraw requests will be attributed to hemolysis.2,4 Each time a hemolyzed specimen is rejected, there may be a 60- to 90-minute delay in providing physicians and/or nurses with valid results. This delay includes time needed to obtain the redraw, transport the specimen, complete preanalytic preparation, and conduct final analysis.4
  2. Determine the causes of hemolysis within the facility. If hemolysis is determined to be the main reason for the majority of redraws, 2. the facility-specific causes need to be identified.2 While this might be difficult to accomplish, conducting a careful review of the processes for each of the causes mentioned above may yield target areas for corrective action.3 A review of where the hemolysis is occurring may be of interest. For example, if a high number of occurrences are from the ED, a focused review of that area might be warranted. Since blood drawing requires some technical expertise, consider conducting periodic reviews of phlebotomy techniques among clinical personnel.
  3. Implement corrective action. Standardizing processes seems to be one of the more effective ways to manage cases of hemolysis.2,4 Spencer et al. recommended creating an easy-to-use visual aid for grading the levels of hemolysis (e.g., slight, moderate, gross) to maintain uniformity and help reduce the subjectivity associated with several people looking at a specimen and rating it differently.4 Solicit input from each technical area within the laboratory as to how its tests are affected by hemolysis, including the exact level of hemolysis that would interfere with each method.5,12 Collate the information into a chart of acceptable levels of hemolysis for specific tests. Document a procedure outlining how testing personnel decide whether to accept a hemolyzed specimen.4 Redraws would be requested only if the specimen failed to meet the facility’s established criteria.5
  4. Monitor results and measure improvement. Consider monitoring redraws and missed venipunctures on a monthly basis.4 With such information, the rate of redraws could be calculated and quality measures put in place to reduce the incidence of these events.2


Hemolyzed specimens represent a unique patient safety concern that is not readily apparent. Monitoring patterns of rejected specimens and analyzing the various causes may help Patient Safety Officers better understand the impact this issue has on patient safety within their facility. Howanitz recommends eight core performance measures for implementation in all laboratories, including customer satisfaction, test turnaround times, patient identification, specimen acceptability, proficiency testing,
critical value reporting, blood product wastage, and blood culture contamination.1

Gaining a better understanding of why a hemolyzed specimen is rejected, coupled with increased physician and nursing staff knowledge about what specific hematology and chemistry tests may be adversely affected by hemolysis, can help facilities reduce the number of hemolyzed specimens, which in turn will help:

  • Facilitate accurate laboratory diagnosis
  • Directly affect patient care and outcome
  • Influence therapeutic decisions
  • Impact patient length of stay, hospital costs, and laboratory costs
  • Influence laboratory efficiency

Reducing the number of hemolyzed specimens may help to reduce risk, improve patient satisfaction, lower utilization, and reduce costs. 


  1. Howanitz PJ. Errors in laboratory medicine: practical lessons to improve patient safety. Arch Pathol Lab Med 2005 Oct;129(10):1252-61.
  2. Jones BA, Calam RR, Howanitz PJ. Chemistry specimen acceptability: a College of American Pathologists Q-Probes study of 453 laboratories. Arch Pathol Lab Med 1997 Jan;121(1):19-26.
  3. Arzoumanian L. What is Hemolysis? Tech Talk 2003 Nov [cited 2007 Mar 21]. Available from Internet:
  4. Spencer LL, Rogers LC. Hemolysis meets QIP (quality improvement process). MLO Med Lab Obs 1995 Oct;27(10):41-2, 44,46.
  5. Carraro P, Servidio G, Plebani M. Hemolyzed specimens: a reason for rejection or a clinical challenge? Clin Chem 2000 Feb;46(2):306-7.
  6. Magee LS. Preanalytical variables in the chemistry laboratory. Lab Notes 2005 [cited 2007 Mar 21] Available from Internet:
  7. Clinical Laboratory and Standards Institute. Procedures for the collection of diagnostic blood specimens by venipuncture; approved standard, fifth edition [consensus standard]. H3-A5. 2003 Dec.
  8. Burns ER, Yoshikawa N. Hemolysis in serum samples drawn by emergency department personnel versus laboratory phlebotomists. Lab Med 2002:33(5):378-80.
  9. Mehaffie, C. Specimen integrity: elevated potassium results [online]. 2003 [cited 2007 May 10]. Available from Internet:
  10. Garza D, Becan-McBride K. Phlebotomy handbook, 5th ed. Stamford (CT): Appleton & Lange; 1999.
  11. ECRI Institute. Needlestick-prevention devices. Health Devices 2003 Sep;32(9):333-64.
  12. Yucel D, Dalva K. Effect of in vitro hemolysis on 25 common biochemical tests. Clin Chem 1992 Apr;38(4):575-7.

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