Question

Maria was admitted to Peace Hospital due to severe stomachache and vomiting for a few days. Based on physical examination, she presented dehydration so the doctor ordered 2 liters of 0.99 % NaCl to drip for 24 hours and also electrolyte tests (Sodium, Potassium, and Chloride). Upon blood collection, the phlebotomist noticed that the IV was inserted to her right dorsal vein and fistula to her left arm. She decided to draw blood on her right median antecubital vein immediately and delivered the sample to its respective section for processing.

1. Did the phlebotomist choose the right site for blood collection? Why?

2. State the reason why a phlebotomist must never place a tourniquet on an arm above an IV site.
3. Describe how a blood sample collected at a site above an IV will be affected and how this will impact the results of laboratory testing performed on the sample.  

Answer 1

There is a risk of obtaining erroneous and misleading results when drawing blood from a patient with an IV catheter. It is recommended using the opposite arm (not the arm with the IV catheter) whenever possible, and when not possible, collecting the specimen below (distal to) the IV site. So since the other arm had the fistula, uSing the right arm was a good choice, but drawing blood above the IV catheter was not the right choice.

Data suggest that collection below the IV with the tourniquet, and from the opposite arm as the IV, are equally effective approaches to collecting blood from a patient with an IV. Although not explicitly asked or stated in this question, a minimum two-minute pause of IV fluids is highly desirable and perhaps more important than the choice of site in terms of avoiding contamination. Blood cannot be drawn above the IV because, blood that is drawn from a vein that has an intravenous (IV) line may be diluted by the IV fluid. This can ultimately affect the accuracy of the blood test results. Therefore, an arm containing an IV should not be used to draw blood specimens if it can be avoided.