Study "the tables", a flashcard deck on FORKSAI.
Why is it important for a requisition form to accompany specimens delivered to the laboratory?
A requisition form ensures that the information on the form matches the information on the specimen label, providing crucial details such as the method of collection, possible interfering medications, and the patient's clinical information, which are essential for accurate testing and diagnosis.
Define the conditions under which a urine specimen should be rejected by the laboratory.
A urine specimen should be rejected if it is in an unlabeled container, if the labels and requisition forms do not match, if it is contaminated with feces or toilet paper, if the container's exterior is contaminated, if the quantity is insufficient, or if it has been improperly transported.
How does improper handling of a urine specimen after collection affect its composition?
Improper handling, such as delays in delivery or testing without preservation, can lead to significant changes in urine composition due to in vitro processes. These changes, often related to bacterial growth, can seriously affect the results of a routine urinalysis.
Why should urine specimens be delivered to the laboratory promptly and tested within 2 hours of collection?
Urine specimens should be delivered and tested promptly to maintain specimen integrity. If left unpreserved at room temperature for longer than 2 hours, significant changes can occur in various analytes, primarily due to bacterial growth and metabolism, which can alter test results.
How does refrigeration at 2°C to 8°C preserve a urine specimen?
Refrigeration at 2°C to 8°C is the most routinely used preservation method because it effectively decreases bacterial growth and metabolism. This helps to maintain the specimen's integrity and prevents changes in its composition that would otherwise occur at room temperature.
Explain why a refrigerated urine specimen must return to room temperature before chemical testing by reagent strips.
A refrigerated urine specimen must return to room temperature before chemical testing by reagent strips because the chemical reactions on the strips are temperature-dependent. Testing a cold specimen could lead to inaccurate or falsely low results.
What are the ideal characteristics of a chemical preservative for urine specimens?
The ideal chemical preservative for urine specimens should be bactericidal, inhibit urease activity, and preserve formed elements in the sediment. Additionally, it should not interfere with chemical tests, although such an ideal preservative does not currently exist.
Why does the color of unpreserved urine become modified or darkened?
The color of unpreserved urine becomes modified or darkened primarily due to the oxidation or reduction of metabolites present in the specimen over time. This chemical change alters the visual appearance of the urine.
How does bacterial growth affect the clarity of an unpreserved urine specimen?
Bacterial growth in an unpreserved urine specimen leads to a decrease in clarity. This is because the multiplication of bacteria, along with the precipitation of amorphous material, makes the urine appear cloudier.
Explain the cause of increased odor in unpreserved urine.
The increased odor in unpreserved urine is caused by bacterial multiplication. These bacteria break down urea into ammonia, which has a distinct, strong odor, leading to the noticeable change in the specimen's smell.