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.
However, if there is no alternative and an arm with an IV line in place must be used for venipuncture, try to choose a site away from and below the location of the IV. Document that the venipuncture was performed distal to (below) an infusion site.
If the only vein available is proximal to (above and near) the IV, these steps should be followed:
- Ask the patient's caregiver if the IV can be turned off for a short period of time. The IV should be discontinued for at least two minutes before the venipuncture.
- Apply the tourniquet between the IV site and the area of the venipuncture.
- Perform the venipuncture.
- Document that the venipuncture was performed proximal to an IV site and that the IV was discontinued for two minutes prior to specimen collection.
- Notify the patient's caregiver when the procedure is completed and be certain that she/he restarts the IV.