Wintrobe Tube & Hematocrit: Best Practices

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Questions and Answers

Why is it important to avoid air bubbles when filling the Wintrobe tube?

Air bubbles can damage the Wintrobe tube, leading to potential blood leakage during centrifugation.
Trapped air bubbles may lead to an inaccurate reading of the packed cell volume. (correct)
Air bubbles can cause the blood to clot prematurely, affecting the accuracy of the hematocrit reading.
Air bubbles interfere with the centrifuge's ability to properly separate blood components.

What is the purpose of balancing the Wintrobe tube with a tube of water in the centrifuge?

To prevent damage to the centrifuge and ensure even distribution of force.
To maintain a constant temperature inside the centrifuge during operation.
To counteract vibrations and ensure proper separation of blood components. (correct)
To calibrate the centrifuge speed and ensure accurate separation of blood components.

What is the significance of the buffy coat layer when reading the hematocrit?

It indicates the presence of abnormal red blood cells and should be included in the hematocrit reading.
It is a precipitate formed by the anticoagulant and must be thoroughly mixed before reading.
It represents the plasma component of the blood and contributes to the overall hematocrit value.
It is a layer of white blood cells and platelets and should be excluded from the red cell column measurement. (correct)

Why should a hemolysed blood specimen not be used for hematocrit determination?

Hemolysis causes the release of hemoglobin into the plasma, leading to falsely low hematocrit values. (D) Signup and view all the answers

Which anticoagulant is recommended for hematocrit determination using the Wintrobe method, and why?

EDTA or double oxalate, because they preserve red blood cell size and shape effectively. (B) Signup and view all the answers

If the blood level in the Wintrobe tube exceeds the 10 cm mark, how should the excess blood be removed, and why?

Use a Pasteur pipette to remove the extra blood, to avoid disturbing or altering the cell distribution. (C) Signup and view all the answers

If a centrifuge used for the Wintrobe method consistently operates at a force significantly less than 2300 g, how would this affect hematocrit readings?

It would result in falsely high hematocrit readings due to incomplete cell packing. (C) Signup and view all the answers

What is the correct speed and duration for centrifuging the Wintrobe tube in the hematocrit procedure?

30 minutes at 3000 rpm (A) Signup and view all the answers

A researcher finds a patient's hematocrit is slightly elevated but their red blood cell count and hemoglobin levels are within normal ranges. Which of the following is the MOST likely explanation for this discrepancy?

The patient is experiencing dehydration, leading to a concentration of red blood cells. (C) Signup and view all the answers

In a clinical laboratory setting, which of the following scenarios would justify the use of the macrohematocrit (Wintrobe) method over the microhematocrit method?

When other tests requiring a larger volume of anticoagulated venous blood are also needed. (B) Signup and view all the answers

Ideally, within what time frame should hematocrit determination be performed after blood collection, and why?

Within 6 hours, to minimize changes in red blood cell volume and prevent clotting. (B) Signup and view all the answers

A female patient's hematocrit is reported as 30%. Considering the normal range for adult females, what does this result likely indicate?

The patient has anemia. (D) Signup and view all the answers

Why is it essential to correlate hematocrit values with red blood cell count and hemoglobin content when interpreting a patient's red blood cell status?

To differentiate between different types of anemia and assess overall red blood cell health. (A) Signup and view all the answers

A phlebotomist consistently fails to properly mix the blood sample with the anticoagulant in the collection tube before performing a manual hematocrit test. How could this affect the accuracy of the hematocrit result, and why?

It will decrease accuracy; the hematocrit result will be falsely high due to clot formation. (D) Signup and view all the answers

A Wintrobe tube is filled with anticoagulated blood, centrifuged, and the plasma appears pinkish-red. How would this affect the hematocrit reading and what is the likely cause?

Falsely high; hemolysis. (D) Signup and view all the answers

If the ascending and descending scales on the Wintrobe tube are accidentally reversed during the reading of erythrocyte sedimentation rate (ESR) and hematocrit, respectively, what would be the MOST direct consequence?

The ESR value would be inaccurate because the scale reads in the opposite direction, leading to a false interpretation of the sedimentation rate. (B) Signup and view all the answers

Why is it important to discard and refill a blood tube if air bubbles enter during the filling process for hematocrit determination?

Air bubbles displace the blood volume, leading to an artificially low hematocrit reading. (D) Signup and view all the answers

What is the primary advantage of using the Wintrobe method for determining ESR and hematocrit simultaneously?

It allows for ESR and hematocrit to be determined from the same sample sequentially, saving time and resources. (C) Signup and view all the answers

Why does using a higher than recommended concentration of anticoagulant, such as EDTA, lead to falsely low hematocrit results?

Excess EDTA may cause hemolysis, leading to a decrease in the measured packed cell volume. (A) Signup and view all the answers

For which patient population is the microhematocrit method particularly well-suited, and why?

Pediatric and burn patients, because it requires only a small volume of blood. (D) Signup and view all the answers

If hematocrit determination cannot be performed within six hours of blood collection, what is the recommended action and why?

Preserve the blood in the refrigerator to slow down metabolic changes and prevent hemolysis. (D) Signup and view all the answers

Why is the hematocrit value of venous blood typically higher than that of arterial blood?

Arterial blood returns a small amount of fluid via lymphatics instead of the veins, and venous blood experiences an increase in osmotically active particles due to CO2. (B) Signup and view all the answers

In the microhematocrit method, what is the purpose of sealing one end of the capillary tube with plasticine or another sealant after filling it with blood?

To prevent leakage of blood during centrifugation. (D) Signup and view all the answers

What is the correct centrifugation speed and duration for a microhematocrit test, and why is it important to adhere to these parameters?

10,000 – 12,000 RPM for 5 minutes, to achieve adequate packing of red blood cells. (A) Signup and view all the answers

What is the primary mechanism behind the sedimentation of red blood cells in the Erythrocyte Sedimentation Rate (ESR) test?

Rouleaux formation, leading to increased weight and settling of red cells. (A) Signup and view all the answers

Why is it critical to use anticoagulated venous blood within six hours of collection for a microhematocrit test?

After six hours, cellular degradation may occur, affecting the accuracy of the hematocrit determination. (B) Signup and view all the answers

In the context of hematocrit determination, what is the most accurate definition of hematocrit?

The percentage of whole blood volume occupied by red blood cells. (B) Signup and view all the answers

What could be the most likely reason for obtaining a falsely low hematocrit reading in a microhematocrit test?

Insufficient centrifugation time. (C) Signup and view all the answers

Which of the following scenarios would most likely result in hemoconcentration and a falsely elevated hematocrit reading?

Severe vomiting and diarrhea leading to dehydration. (B) Signup and view all the answers

Why is it important to differentiate between Erythrocyte Sedimentation Rate (ESR) and Packed Cell Volume (PCV) or Hematocrit?

ESR measures the settling of red cells due to gravity, while PCV measures the percentage of red cells after centrifugation. (D) Signup and view all the answers

A phlebotomist is performing a microhematocrit test using capillary blood from a finger puncture. After centrifuging the sample, they observe that the plasma appears hemolyzed (reddish). What is the most appropriate course of action?

Repeat the finger puncture and collect a new sample, ensuring gentle handling to avoid hemolysis; discard the hemolyzed sample. (A) Signup and view all the answers

Rouleaux formation plays a crucial role in the Erythrocyte Sedimentation Rate (ESR). Which of the following best describes rouleaux?

The stacking of red blood cells resembling a pile of coins. (D) Signup and view all the answers

Which of the following directly inhibits rouleaux formation, leading to a decreased ESR?

Increased blood viscosity as seen in polycythemia. (B) Signup and view all the answers

In a patient with acute rheumatic fever, which factor contributes most significantly to an elevated ESR?

Increased levels of C-reactive protein. (B) Signup and view all the answers

How does anemia typically affect the ESR, and why?

Raises ESR due to decreased blood viscosity. (B) Signup and view all the answers

Why does sickle cell disease, despite often causing anemia, typically result in a lower ESR than other types of anemia?

The altered shape of red blood cells in sickle cell disease inhibits rouleaux formation. (A) Signup and view all the answers

What is the primary role of fibrinogen in influencing the ESR?

It neutralizes the negative charges on red blood cells, promoting rouleaux formation. (B) Signup and view all the answers

How does increasing the temperature of a blood sample affect the ESR, and what is the underlying mechanism?

Increases ESR by decreasing blood viscosity. (C) Signup and view all the answers

A patient has polycythemia vera. What effect would you expect this condition to have on their ESR?

Significantly decreased ESR due to increased blood viscosity. (B) Signup and view all the answers

During an inflammatory response, acute-phase reactants like C-reactive protein increase in the blood. What direct effect do these reactants have on red blood cells that influences ESR?

They neutralize the negative charges on red blood cells, facilitating rouleaux formation. (A) Signup and view all the answers

Why is the Westergren method considered more sensitive than the Wintrobe method for determining ESR?

It employs longer and narrower tubes, providing a more accurate measurement of the settling distance. (B) Signup and view all the answers

What is the correct ratio of blood to 3.8% sodium citrate anticoagulant in the Westergren method, and why is it important?

4:1, to ensure proper anticoagulation without affecting red cell sedimentation. (C) Signup and view all the answers

In the Westergren method, what could be the most likely cause if the blood sample shows signs of clotting despite the addition of sodium citrate?

The blood-to-citrate ratio was incorrect, with too much blood. (C) Signup and view all the answers

Why should the Westergren setup be kept away from direct sunlight and at a temperature not higher than 27°C?

To minimize the risk of bacterial contamination of the sample. (B), To avoid temperature-induced changes in blood viscosity and prevent erroneous ESR results. (C) Signup and view all the answers

A phlebotomist consistently observes air bubbles in the Westergren tube after filling it. Besides compromising the reading, what specific effect might these bubbles have on the ESR?

Slow down the ESR, creating artificial impedance to the settling of erythrocytes. (B), Have no significant effect on the ESR reading as long as the blood level reaches the 0 mark. (D) Signup and view all the answers

A lab technician notices that the ESR results for all samples processed on a particular day are significantly higher than normal. Which of the following is the most likely pre-analytical error influencing these results?

Positioning the Westergren stand at a slight angle. (B) Signup and view all the answers

A researcher is investigating the effect of a new drug on inflammation and uses ESR as one of the markers. If the drug reduces inflammation, how would you expect the ESR to change, and why?

Fluctuate randomly, as drug effects on ESR are unpredictable. (A), Decrease, because reduced inflammation lowers the concentration of acute-phase proteins. (C) Signup and view all the answers

A newborn shows an ESR of 3 mm/h using the Westergren method. Considering the provided reference ranges, how should this result be interpreted?

Significantly elevated, indicating an acute inflammatory process. (C) Signup and view all the answers

Flashcards

Hematocrit (PCV)

Percentage of blood volume occupied by packed red blood cells.

Hematocrit as an Index

A reliable indicator of the red cell population in the blood.