Common Causes of Hemolysis in Blood Samples and How to Prevent Them

Illustration of blood samples being collected

Addressing the issue of hemolysis in blood samples is crucial for accurate lab results and optimal patient care. Hemolysis, the rupture of red blood cells, poses a significant risk to sample integrity, potentially leading to skewed lab results and jeopardizing patient care. This article delves into the common causes of hemolysis and offers practical strategies for healthcare professionals to prevent it throughout the entire process. By understanding and implementing these preventive measures, healthcare professionals can enhance the reliability of blood samples and contribute to more accurate diagnostic outcomes.

Key Takeaways

  • Hemolysis in blood samples, often occurring in the preanalytical phase, results from factors like improper handling, incorrect needle size, and prolonged tourniquet time.
  • Best practices for preventing hemolysis involve employing proper specimen collection techniques, ensuring gentle sample handling and transportation, selecting appropriate equipment, and minimizing tourniquet time.
  • Hemolysis can substantially affect patient care, introducing false readings in laboratory tests that may lead to delayed treatment and diagnosis.

Identifying Common Causes of Hemolysis in Blood Samples

In laboratory testing, maintaining blood specimen integrity is crucial. Hemolysis, the breakdown of red blood cells, can compromise sample quality, leading to inaccurate test results, potential misdiagnosis, and delayed treatment. Hemolysis often occurs in the preanalytical phase due to factors like improper specimen handling, incorrect needle size, and extended tourniquet time. Recognizing and addressing these causes are vital steps in ensuring accurate diagnostics and improving patient outcomes.

Improper Specimen Handling

Blood specimens face potential pitfalls in their journey from vein to vial. Mechanical destruction of red blood cells can occur if the specimen undergoes vigorous mixing, such as with a metallic flea or squeezing through a narrow syringe, leading to hemolysis. This jeopardizes sample quality and raises doubts about laboratory result reliability.

Moreover, the method of mixing, be it mechanical or manual, must be carefully calibrated. Excessive agitation or inadequate mixing can either destroy red blood cells or prevent the proper dissolution of anticoagulants, respectively. Variability in technique among healthcare providers can further contribute to inconsistent results. Even actions as seemingly trivial as shaking a blood sample can have deleterious effects, emphasizing the need for standardization and care in every interaction with the specimen.

Incorrect Needle Size

The importance of needle size in blood sample collection is often underestimated, but it plays a crucial role in the process. Using a needle that is either too large or too small can have significant implications. A needle that is too large may cause unnecessary trauma to the vein, increasing the risk of hemolysis. Conversely, a needle that is too small, particularly below the gauge of 23, can also lead to hemolysis when blood flow is forced or the collection tube is not filled adequately.

Achieving the right balance with a correctly sized needle is essential. It minimizes contact between the vein wall and the needle, reducing the likelihood of hemolysis.

Excessive Tourniquet Time

While applying a tourniquet is a standard procedure in blood collection, it’s essential to recognize that excessive tourniquet time can invite hemolysis. Leaving a tourniquet on the patient’s arm for more than one minute significantly increases the risk of rupturing red blood cells. This excessive pulling pressure can cause turbulence in the circulating blood, leading to the mechanical breakdown of cells against the vein wall.

Healthcare professionals are trained to be swift and efficient to prevent this risk. They ensure the tourniquet is released as soon as the blood collection tube begins to fill. This practice not only reduces the likelihood of hemolysis but also enhances patient comfort. It underscores the notion that, in some cases, the most effective strategy is simply to save time.

Best Practices for Preventing Hemolysis

Photo of proper specimen collection techniques

Combatting hemolysis demands a multifaceted approach: employing proper specimen collection techniques, gentle sample handling, and careful tourniquet application. These practices aren’t mere guidelines; they are vital for maintaining blood sample integrity from collection to analysis. Adhering to these best practices is crucial for healthcare professionals, ensuring that collected blood specimens accurately reflect the patient’s health status.

Proper Specimen Collection Techniques

Efficient specimen collection requires a combination of knowledge and skill to ensure a seamless procedure. Key to this process is the careful selection of the appropriate needle size, a critical factor in minimizing shear stress on delicate red blood cells. Equally important is the meticulous treatment of the venipuncture site, with thorough disinfectant drying to prevent contamination and cellular damage.

Performing venipuncture away from intravenous devices is a strategic move, mitigating the heightened risk of hemolysis associated with line draws. In addition, correct needle positioning is imperative to avoid occlusion by the vein wall. These precise techniques, when executed accurately, collectively safeguard the quality of the collected sample.

Gentle Sample Handling and Transportation

Even after the blood has been drawn, the process is not yet complete. The way a sample is handled and transported can be just as important as the initial draw. Here are some important steps to follow:

  • Gentle mixing, according to the manufacturer’s instructions, is necessary to prevent hemolysis.
  • Exercise care when removing the needle from the syringe.
  • Transfer the blood gently to the collection tube to avoid agitation, preventing potential cell rupture.

Following these steps will ensure that the blood sample remains intact and suitable for testing.

When it comes to transportation, the samples deserve the utmost care. They should be cushioned with foam or bubble wrap to prevent any jostling or shaking that could induce hemolysis. If the samples are being transported over longer distances, they may require an insulated container with a cold pack to maintain their integrity. These precautions ensure that the sample reaches the laboratory in the best condition possible, ready for accurate analysis.

Reducing Tourniquet Time

Mitigating hemolysis is contingent upon minimizing tourniquet time, a critical aspect of blood specimen collection. Adhering to best practices in this regard not only significantly reduces the risk of hemolysis but also prevents excessive pulling pressure. Healthcare professionals can achieve this by promptly releasing and removing the tourniquet as soon as the first tube starts to fill. This action minimizes pressure on the patient’s veins, contributing to the overall integrity of the collected blood sample.

Continuous education on the importance of promptly releasing the tourniquet is essential in fostering a culture that prioritizes patient safety. In addition to managing tourniquet time, other strategies play a role in minimizing hemolysis. Pre-warming the skin puncture site is one such approach, diminishing the need for excessive squeezing, which is another potential cause of hemolysis. The use of transillumination to locate veins further aids in reducing the risk of hemolysis by eliminating venous stasis caused by the tourniquet.

The Role of Equipment in Hemolysis Prevention

Illustration of equipment selection for blood collection

The equipment chosen for blood collection plays a pivotal role in hemolysis prevention. Factors such as needle gauge selection, the use of low vacuum tubes, and the optimization of pneumatic tube systems significantly impact hemolysis rates. When selected and utilized correctly, this equipment acts as a formidable defense against hemolysis, preserving the integrity of blood samples.

Choosing the Right Needle Gauge

In navigating the nuanced decisions surrounding needle gauge selection, healthcare professionals often find the 21-gauge needle to be the optimal choice. This particular size strikes a delicate balance, minimizing the risk of hemolysis while prioritizing patient comfort. Smaller needles, typically larger than 21 gauge, tend to elevate the likelihood of hemolysis, whereas larger needles offer a gentler path for the blood to traverse.

Utilizing Vacuum Tubes

Vacuum tubes are a game-changer in the world of blood collection. By reducing the blood transfer rate, these tubes minimize the stress exerted on red blood cells, thereby lowering hemolysis rates. These tubes are especially effective when drawing blood from intravenous catheters, a common procedure that comes with its own set of challenges.

The adoption of these tubes offers several benefits:

  • It does not require significant behavioral changes from medical staff
  • It does not impose additional economic burdens on hospitals
  • It makes blood collection safer and more reliable

Implementing Pneumatic Tube Systems

As blood samples are transported through the hospital’s pneumatic tube system, it’s crucial to assess and optimize these conduits to prevent hemolysis. While this system’s swift delivery of samples to the lab is a marvel of modern medicine, without proper calibration, it can result in a rough ride for the specimens.

Healthcare facilities need to make sure the pneumatic tube system treats samples gently. This helps prevent unnecessary damage to red blood cells and keeps the blood specimens intact during transport.

Training and Education for Healthcare Professionals

In the ongoing efforts to prevent hemolysis within healthcare settings, the significance of comprehensive training and education for healthcare professionals cannot be overstated. These individuals, often serving as the initial point of contact with patients, play a critical role in ensuring the highest quality of patient care. Accredited phlebotomy programs serve as the backbone of this training, equipping professionals with a profound understanding of human anatomy, physiology, and blood collection techniques, crucial elements in reducing hemolysis rates.

The journey of learning in healthcare is perpetual, reflecting the dynamic nature of the field. Continuous education emerges as the compass guiding professionals toward excellence. Through these educational opportunities, healthcare workers remain updated on the latest strategies for preventing hemolysis, thereby maintaining practices at the forefront of patient care.

Within the realm of phlebotomy training programs, such as the comprehensive NCC Phlebotomy program, healthcare professionals are honed into skilled practitioners. Covering everything from the art of drawing blood to the science of handling specimens, these programs delve into the intricacies of phlebotomy. It’s not solely about technical skills; these programs also instill the ability to manage the pressures associated with blood collection procedures, provide compassionate patient care, and implement crucial techniques like pre-gloving tourniquet application. This well-rounded training is indispensable for healthcare professionals, ensuring competence and confidence in their duties.

The Impact of Hemolysis on Patient Care and Laboratory Testing

The impact of hemolysis extends beyond the laboratory, affecting patient care and laboratory testing. When hemolysis occurs, it can lead to:

  • False readings and errors in laboratory analysis, thus, hindering accurate diagnoses and effective treatment.
  • Biased readings in tests like cardiac troponin levels potentially interfering with heart condition detection.
  • Delays in patient care, occurring six times more frequently than issues related to insufficient sample volume.

The repercussions of hemolysis in patient blood samples create a ripple effect, influencing medical diagnoses and distorting results in analyte detection. Confronting this challenge demands a vigilant and proactive approach, underscoring the necessity for precise practices and accurate detection methods to ensure the optimal care for patients.

Effects on Test Results

Hemolysis can trigger a series of distortions in laboratory test results. It releases intracellular contents like potassium, which can cause false readings and lead clinicians down a misguided path of diagnosis. The altering of results doesn’t stop there; analytes such as LDH, AST, ALT, and several others are also affected, leading to dilution of the serum or plasma and ultimately unfavorable test outcomes. This can result in indirect harm, such as increased patient length of stay, additional healthcare expenses, and the psychological toll of extra blood draws.

Laboratories may have different practices for detecting and reporting hemolysis, which can lead to inconsistent test results and affect patient care. The challenge is to ensure that the detection of hemolysis is as precise as the tests it affects, requiring a standard that all laboratories can adhere to, ensuring that every patient receives accurate results and the best possible care.

Implications for Patient Care

Hemolyzed samples, including those from blood, carry extensive implications that extend beyond mere specimen rejection and the need for repeat tests. They instigate delays in treatment and diagnosis, with potentially severe consequences for patient health. Clinicians frequently find themselves grappling with decisions, torn between:

  • Rejecting or releasing results from hemolyzed samples.
  • Conducting additional tests to validate result accuracy.
  • Collaborating with other healthcare professionals to chart the optimal course of action.

These decisions wield significant influence in patient treatment, especially in urgent care scenarios.

Strategies for Addressing Hemolyzed Samples

Implementing a proactive approach empowers healthcare professionals to develop effective strategies for managing hemolyzed samples. Key considerations include the proper storage of serum samples, where serum should be promptly transferred to a sample tube and stored at 4°C for tests within 48 hours of collection. Alternatively, it should be aliquoted and stored at -20°C for tests conducted beyond this timeframe. Standard operating procedures within clinical laboratories play a pivotal role in detecting, analyzing, and reporting hemolysis, and understanding its potential influence on test results.

The utilization of Automated Hemolysis Index (HI) assessments on chemistry analyzers provides a standardized method for handling hemolyzed specimens. This approach brings clarity and consistency to decision-making processes. Additionally, fostering effective communication between clinicians and laboratory specialists is indispensable, particularly in scenarios where new blood samples are unavailable. This ensures that patient care remains uncompromised. Together, these strategies constitute a comprehensive approach to managing hemolyzed samples, working to minimize their impact on patient care while upholding the accuracy and reliability of laboratory testing.


In hemolysis prevention, it is clear that each step in the process of collecting and handling blood samples holds great importance. From the precise technique employed during blood extraction to the cautious transport and analysis of specimens, every step bears significant weight. Through the implementation of best practices, the correct use of equipment, and the ongoing education and training of healthcare professionals, the rates of hemolysis can be significantly reduced, enhancing patient care and the accuracy of laboratory testing.

Further Reading

Frequently Asked Questions

What are the factors that increase the risk of hemolysis?

Hemolysis can occur due to factors like infection, certain medications, autoimmune disorders, and genetic conditions, all of which increase the risk of red blood cell destruction.

How do you control hemolysis?

In addressing hemolysis, effective management involves various treatment options. These include blood transfusions, corticosteroid medications, immune system support, and the application of rituximab. To preemptively curb hemolysis, implementing best practices is key. This entails using the correct needle size for blood collection, avoiding butterfly needles unless explicitly requested, warming the venipuncture site, and ensuring thorough drying of the applied disinfectant.

What steps can be taken by a phlebotomist to prevent a hemolyzed sample?

To prevent hemolyzed samples, a phlebotomist must employ the correct needle size and apply appropriate pressure during blood collection.

How does hemolysis affect laboratory testing?

Hemolysis can lead to false readings and errors in laboratory tests by altering analyte levels and reaction pH. It can release substances like potassium, which may distort test results and impact diagnosis or treatment.