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:
When performing a capillary blood collection, such as a fingerstick, the lancet should be positioned perpendicular to the fingerprint grooves. This orientation helps to ensure that the incision is made across the ridges of the fingerprint, which can facilitate a better blood flow and make it easier to collect an adequate sample without needing to squeeze the finger excessively, which could hemolyze the sample.
Choice B reason:
Positioning the lancet parallel to the nail bed is not recommended because it can result in a cut that runs along the length of the fingerprint grooves, which may not bleed as freely and could also be more painful for the patient.
Choice C reason:
Using the lancet along the lateral portion of the first digit is not part of the standard aseptic technique protocol for capillary blood collection. The first digit, or thumb, has a pulse and should generally be avoided because it can be more sensitive and is more prone to bruising.
Choice D reason:
The medial portion of the fifth digit, or the little finger, is also not a recommended site for capillary blood collection with a lancet. The little finger is typically smaller and may not provide an adequate site for blood collection, and similar to the thumb, it can be more sensitive and prone to injury.
Correct Answer is D
Explanation
Choice A Reason:
The right antecubital fossa is not the optimal site for blood collection in this case because the presence of a shunt in the right forearm can complicate the procedure and potentially damage the shunt, which is a critical access point for dialysis treatments.
Choice B Reason:
The right hand should also be avoided for blood collection due to the shunt placement in the right forearm. Using the same arm as the shunt for venipuncture could lead to complications such as infection, clotting, or accidental damage to the shunt.
Choice C Reason:
The left antecubital fossa might seem like a viable option; however, with an IV placed in the left hand, it is generally recommended to avoid using the same limb for blood collection to prevent contamination of the sample and reduce the risk of infection at the IV site.
Choice D Reason:
Capillary collection from the left hand is the most appropriate choice in this scenario. It avoids the arm with the shunt and the IV, reducing the risk of complications. Capillary blood collection is a suitable alternative when venipuncture sites are limited, and it can provide an adequate sample for a CBC.
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