Which of the following is caused by excessive shaking of a tube?

Choice A reason:
Capturing the initial stream of urine, also known as the "first catch," is not recommended for a urine culture. This part of the urine stream can contain contaminants from the urethral opening and is not ideal for culture testing, which requires a clean sample.

Choice B reason:
Cleaning the genital area prior to collection is crucial for obtaining a clean-catch urine specimen. This reduces the risk of contamination from bacteria that are normally present on the skin around the urinary opening. Patients should be instructed to use antiseptic wipes to clean the area before collecting the urine sample.

Choice C reason:
Filling the container to capacity is not necessary and is not a specific instruction for urine culture collection. The focus should be on obtaining a midstream sample after the genital area has been cleaned, which provides a more accurate representation of the urine for culture purposes.

Choice D reason:
Labeling the lid prior to collection is an important step in the process to ensure proper identification of the specimen. However, it is not the primary instruction related to the actual collection of the urine sample. The label should include the patient's name, date, and time of collection and should be done after the sample is collected to avoid confusion or contamination.

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.