Question

I work in a very busy Procedure Center at the University of Connecticut. We draw a great deal of blood off our IV sites using a vacuum tube collection system or syringe. More often than not the Type and Screen or Type and Cross will be reported back within an hour as "hemolyzed."

I have looked into everything, including the amount of time the tourniquet is on the person, the amount of time of blood flow into the large red top tube, the use of a large vein versus a small vein, and the amount of time between drawing the blood and having it sent from the OR to the laboratory.

Do you have any valid documentation as to why we have this problem? It is very frustrating and also time consuming, not to mention what the patient is thinking and feeling, when we have to redraw the bloodwork.

Answer

Hemolysis is, without question, the BIGGEST problem standing between caregivers and the laboratory.

The hemolysis issue is a recurring one, both in this column and many times each and every day in healthcare centers. The primary reason for it is the use of the IV set up to obtain the blood. It is meant to allow flow of liquids into the body. When used as a port to obtain a blood sample, a portion of the red cells (there 4-6 million of them per microliter of blood) break as they physically go through the inlet port of the IV in reverse.

Large evacuated collection tubes (10 ml) will also be more likely to be hemolyzed due to the amount of vacuum in them, which can at times disrupt red cell membranes causing cell breakage.

To significantly reduce this problem, which we in the lab refer to as a "preanalytical error", a number of medical centers have adopted the policy of not using the IV line to obtain blood samples. A direct venipuncture, in addition to significantly reducing the occurrence of hemolysis, eliminates of other problems dealing with contaminating the blood collection tube with residual saline when the IV line is flushed. 

For further information, see "Factors Affecting the Risk of Blood Bank Specimen Hemolysis," a study published in the August 2003 issue of Academic Emergency Medicine. Go to http://www.aemj.org/cgi/content/abstract/10/8/897 for a free abstract of the study. There is a fee to view the full text of the study for those who are not members of the Society for Academic Emergency Medicine. 

Additionally, read "Seeing red? An answer to nurses' questions regarding hemolyzed blood specimens," from the online archives of ADVANCE for Nurses, at  http://nursing.advanceweb.com/Editorial/Content/editorial.aspx?CC=92211

Sally Perry Ball is a faculty member of the Medical Laboratory Science Department at Northeastern University and a freelance writer.