Blood draw for complete blood count (CBC) is collected with which ingredients?

Appeared in: BHU NO - 2015

Explanation

Blood for a Complete Blood Count (CBC) is collected in a vial containing Ethylenediaminetetraacetic acid (EDTA).
EDTA acts as an anticoagulant by chelating (binding) calcium ions, which are essential for the blood clotting cascade.
Preventing clotting is crucial to ensure that individual blood cells (red cells, white cells, and platelets) remain suspended in plasma and can be accurately counted.
The vial for a CBC test is typically identifiable by its lavender or purple-colored top.

Option B: A monocyte is a type of large white blood cell (leukocyte) that is part of the body's immune system. Its quantity is measured during the differential component of a CBC, but it is not an additive in the collection tube.
Option C: A lymphocyte is another type of white blood cell crucial for the adaptive immune response. Like monocytes, lymphocytes are counted in a CBC, not used to prepare the sample.
Option D: An eosinophil is a type of granulocytic white blood cell involved in combating parasitic infections and allergic reactions. It is a cell type quantified by the CBC, not a collection ingredient.

Clinical Relevance

Nursing practice connection: Knowing Anticoagulants for hematological tests helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Using the correct collection tube is a critical pre-analytical step. Using the wrong tube can lead to sample rejection, requiring a redraw and causing delays in diagnosis and treatment.
Nurses must always confirm the required tube for each specific lab test as per the facility's protocol, which is often detailed in a lab manual or on the electronic order.
After collection, EDTA tubes must be gently inverted 8-10 times to ensure the anticoagulant is thoroughly mixed with the blood to prevent micro-clots, which can interfere with automated counters.

How to Approach the Question

First, identify the core of the question: it asks about the ingredient used for collecting a blood sample for a CBC.
Analyze the options provided. You should recognize 'EDTA vial' as a piece of laboratory equipment containing a chemical.
Recall or deduce that 'Monocyte,' 'Lymphocyte,' and 'Eosinophil' are all types of blood cells.
The question asks what the blood is collected with, not what is being measured in the blood.
Therefore, the blood cells are the subject of the test, not the collection medium.
This process of elimination leaves 'EDTA vial' as the only logical answer related to sample collection.

Concept Tested & Keywords

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E6 PATHOLOGY QUICK REVIEWBased on Harsh Mohan Textbook of PATHOLOGY p. 97-99

E6 Pathology-Vandana Puri & Kavita Gaur Textbook of Pathology and Genetics p. 384-386

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