Hemoconcentration of a venous blood sample is most often caused when:
The site is prepped with povidone iodine.
The tourniquet is in place for more than 2 minutes.
The specimen is not refrigerated within 30 minutes.
The needle is removed before the tourniquet.
The Correct Answer is B
Choice A Reason:
Prepping the site with povidone iodine is not typically associated with hemoconcentration. Povidone iodine is used as an antiseptic to clean the skin before venipuncture to prevent infection. While it's important to allow it to dry to avoid sample contamination, it does not cause hemoconcentration.
Choice B Reason:
Leaving the tourniquet in place for more than 2 minutes can lead to hemoconcentration. A tourniquet is applied to engorge the veins, making them easier to puncture. However, prolonged application can result in fluid being forced out of the vein into the tissue, increasing the concentration of cells and larger molecules in the blood. This can affect certain laboratory test results by artificially increasing the levels of cellular components.
Choice C Reason:
Not refrigerating the specimen within 30 minutes does not cause hemoconcentration. However, it can affect the stability of certain analytes in the blood sample. Refrigeration is necessary for preserving the integrity of certain components of the blood until analysis, but it is unrelated to the concentration of cells within the sample at the time of collection.
Choice D Reason:
Removing the needle before the tourniquet is released does not cause hemoconcentration. This action might lead to other complications, such as hematoma formation, but it does not affect the concentration of cellular elements in the collected sample.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is D
Explanation
Choice A Reason:
The age of the newborn is important for certain metabolic screenings, as some metabolites may not be present or at measurable levels immediately after birth. However, the requirement for the newborn to be at least 3 days old is not a standard for all blood spot collections for inborn errors of metabolism (IEM). Some screenings are performed within 24 to 48 hours after birth.
Choice B Reason:
While it is important that the circles on the filter paper are adequately filled to ensure there is enough blood for the test, the requirement for them to be at least half filled is not specified in the guidelines. The focus is usually on ensuring the blood spot is of the right size and properly saturated through the filter paper.
Choice C Reason:
The inclusion of the first drop of blood is not typically a requirement. In fact, the first drop is often wiped away to avoid contamination with tissue fluids that could affect the test results. Subsequent drops are used to fill the circles on the filter paper.
Choice D Reason:
The specimen must be completely dried before the test can be processed to prevent degradation or hemolysis of the blood sample. This is a critical step in the preparation of the sample for accurate testing of IEM. The drying process helps preserve the integrity of the metabolites to be analyzed.
Correct Answer is A
Explanation
Choice A reason:
Chilling the sample is the correct method for preparing a lactic acid sample for processing and transportation. Lactic acid levels can continue to change after the blood is drawn due to ongoing cellular metabolism. Chilling the sample slows down this metabolism, preserving the accuracy of the lactic acid measurement. The sample should be placed on ice or in a refrigerated environment as soon as possible after collection.
Choice B reason:
While protecting the sample from light is important for some types of specimens, it is not the primary concern for lactic acid samples. The key factor for lactic acid stability is temperature control, not light exposure. Therefore, while it may be beneficial to keep the sample out of direct sunlight, chilling it is the priority to prevent changes in lactic acid levels.
Choice C reason:
Attaching a heat block to the sample is not a recommended method for lactic acid samples. Heat can increase metabolic activity, potentially altering the lactic acid levels in the sample. This would lead to inaccurate results, as the goal is to preserve the state of the sample at the time of collection.
Choice D reason:
Freezing the sample is not typically recommended for immediate processing and transportation of a lactic acid sample. While freezing can preserve certain types of specimens for long-term storage, it is not necessary for short-term transport and can cause issues such as hemolysis, which may interfere with the test results.
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