Which of the following is used to stabilize a patient's arm during a venipuncture?

Choice A reason:
Expired tubes may lose their vacuum, which is necessary to draw the correct volume of blood into the tube. The vacuum in blood collection tubes ensures that the correct amount of blood is drawn. If the vacuum is lost, the blood will not be drawn into the tube properly, which can lead to underfilling and affect the test results.

Choice B reason:
Hemoconcentration refers to an increase in the concentration of cells and solids in the blood, usually because of a loss of plasma. While this can occur due to prolonged tourniquet application or dehydration, it is not directly caused by the use of expired tubes.

Choice C reason:
Hemolysis is the destruction of red blood cells, which can release hemoglobin and other intracellular components into the plasma. It can be caused by physical damage, such as from a needle during blood draw, but is not a consequence of using expired tubes. However, if an expired tube causes improper blood draw due to loss of vacuum, it could indirectly lead to hemolysis due to multiple attempts to draw blood.

Choice D reason:
An elevation of the red blood cell count would not be directly caused by using expired tubes. The red blood cell count is determined by the body's production and destruction of red blood cells, not by the collection method or equipment used.

Choice A Reason:

Positioning the needle at a 45° angle to the skin is not the recommended approach for venipuncture using a butterfly needle on dorsal hand veins. The correct angle for insertion is usually less than 45°, often around 15-30°, to ensure a shallow entry and reduce the risk of going through the vein.

Choice B Reason:

Holding the needle by the wings of the butterfly is the correct technique. This allows for better control and stability during insertion. The wings are designed to be held between the thumb and forefinger, providing an easy grip for the phlebotomist to maneuver the needle with precision.

Choice C Reason:

Instructing the patient to hold the collection tubes is not standard practice and could lead to pre-analytical errors. The phlebotomist should maintain control of the tubes to ensure proper blood flow and fill volume, as well as to prevent contamination or accidents.

Choice D Reason:

Applying the tourniquet at the antecubital area is not specific to the use of a butterfly needle for venipuncture on dorsal hand veins. While a tourniquet is used to engorge the veins and make them more prominent, its placement may vary depending on the selected puncture site and is not the action in question here.