When using the evacuated tube method, which of the following will result in a failed venipuncture if the needle is at a 45° angle upon insertion?
The needle will collapse the vein.
The needle will go completely through the vein.
The needle will miss the vein superficially.
The needle will contact the upper wall of the vein.
The Correct Answer is B
Choice A reason:
Using a needle at a 45° angle does not typically result in collapsing the vein. A collapsed vein is more likely due to excessive vacuum pressure from the tube, a very small or fragile vein, or the tourniquet being too tight.
Choice B reason:
At a 45° angle, the needle is more likely to penetrate through the entire depth of the vein, especially if the vein is superficial. This can result in a failed venipuncture because the needle has entered and exited the vein, missing the opportunity to collect blood.
Choice C reason:
While a steep angle like 45° could cause the needle to miss the vein superficially, it is more likely that the needle would go through the vein at this angle rather than merely missing it superficially. A superficial miss is more likely with an angle that is too shallow.
Choice D reason:
Contacting the upper wall of the vein alone would not necessarily result in a failed venipuncture. However, at a 45° angle, the needle could easily slip through the vein entirely after contacting the upper wall, especially if the vein is not anchored well.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
Choice A Reason:
SST, or Serum Separator Tube, contains a gel at the bottom to separate the blood from the serum upon centrifugation. It does not indicate plasma; rather, it is used to collect serum after the blood has clotted. The SST allows for the blood to clot and the serum to be separated for various tests that require serum instead of plasma.
Choice B Reason:
Sodium fluoride is a common additive in collection tubes that serves as a glycolysis inhibitor. It preserves glucose levels and is not specifically indicative of serum. However, it is often used in grey-top tubes, which are typically used for glucose testing and may contain plasma, not serum.
Choice C Reason:
Sodium citrate is an anticoagulant that binds calcium in the blood, preventing clotting. Tubes with sodium citrate are used to collect plasma for coagulation studies, not serum. Therefore, this statement is incorrect as sodium citrate indicates plasma, not serum.
Choice D Reason:
EDTA, or Ethylenediaminetetraacetic acid, is an anticoagulant that binds calcium ions, preventing blood from clotting. Tubes with EDTA are used for collecting plasma because they prevent clotting and allow for the separation of plasma from the blood cells upon centrifugation. This is the correct choice as EDTA indicates plasma.
Correct Answer is B
Explanation
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.
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