The Hemolyzed Sample
You are training a new phlebotomist, Alex. He is drawing blood from a 30-year-old female for a basic metabolic panel (BMP) and a lipid panel. He uses a 22-gauge needle and a 10 mL syringe because he needs to fill a 5 mL gold top tube and a 4 mL green top tube. He pulls back on the syringe plunger forcefully to speed up the draw. The blood appears slightly frothy. He then transfers the blood into the tubes by pushing the plunger down hard. After the draw, you notice the serum in the gold top tube is pinkish-red after centrifugation. The patient asks if everything is okay.
1. What error did Alex make, and what are the consequences?
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Alex made several errors: 1. Excessive suction: Pulling back forcefully on the syringe plunger can cause hemolysis (rupture of red blood cells) due to turbulence and shear stress. 2. Forcing blood into tubes: Pushing the plunger down hard to transfer blood increases pressure and can also cause hemolysis. 3. Using a syringe for a routine draw: Unless veins are fragile, a syringe is not necessary; a butterfly or straight needle with vacuum tubes is preferred. Consequences: Hemolysis releases intracellular contents (e.g., potassium, LDH, hemoglobin) into the serum, falsely elevating potassium and LDH, and interfering with spectrophotometric assays. The pinkish-red serum indicates hemolysis. The BMP results for potassium may be falsely elevated, which could lead to inappropriate treatment. The lipid panel may also be affected. The specimen should be rejected and recollected.
2. How should Alex have performed the draw to avoid hemolysis, and what should you do now?
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Correct technique: 1. Use a straight needle or butterfly with vacuum tubes if possible, to avoid syringe suction. 2. If a syringe is necessary, pull back slowly and steadily; do not force. 3. Transfer blood gently into tubes by allowing the vacuum to draw the blood (if using a syringe, remove the needle and let blood flow down the side of the tube) or use a transfer device. 4. Do not push the plunger; let the vacuum in the tube pull the blood. Now: 1. Inform the patient that a small amount of blood will need to be redrawn because the sample was not suitable. 2. Discard the hemolyzed specimen. 3. Recollect using proper technique, preferably with a butterfly and vacuum tubes. 4. Document the incident and provide feedback to Alex.