Hemolysis of coagulation specimens: a comparative study of intravenous draw methods

Hemolysis of blood samples creates significant delays in the treatment and disposition of patients in the emergency department. The purpose of this study was to compare the hemolysis rates of coagulation blood samples obtained during insertion of an intravenous (IV) catheter without (group 1) or with (group 2) extension tubing connected to the IV catheter hub. A secondary purpose of this study was to determine whether the investigators could predict whether a coagulation sample was hemolyzed based on visual observation during the specimen withdrawal process.

A prospective, 2-group randomized comparative design was used to determine which method of blood collection for coagulation specimens provided the lowest hemolysis rate. This study was conducted in an urban level I emergency department averaging 58,000 visits per year. The sample consisted of 121 adult ED patients randomly assigned to 1 of the 2 groups. Data collectors were trained in the 2 methods of coagulation sample collection and followed a strict protocol. The clinical laboratory used a standardized color-coded scale to determine hemolysis.

Pearson χ(2) analysis was used to test for differences between all nominal variables. The level of significance for all tests was P < .05. There was no significant difference in hemolysis rates between the groups by use of χ(2) analysis (P = .84). Nurses were significantly more likely to predict that a sample was hemolyzed when it was not and to think that it was not hemolyzed when in fact it was (P < .001).

High hemolysis rates occurred equally when coagulation blood samples were drawn via a peripheral IV catheter either at the hub or through extension tubing. Emergency nurse investigators could not accurately predict by visualization whether a coagulation sample was hemolyzed at the time of blood withdrawal. Venipuncture as the preferred method of blood draw is an industry recommendation. This method has been shown in prior experimental studies to reduce hemolysis rates to less than 4%. Therefore, if hemolysis rates are a concern, one should consider obtaining blood whenever possible through a venipuncture rather than through an IV catheter. Replication studies are needed to determine whether the findings of this study can be generalized to the larger population.