MICROHEMATOCRIT

Question 1

The volume of packed RBCs that occupies a given volume of whole blood.

Answer 1

Hematocrit

Question 2

Hematocrit aka

Answer 2

Packed cell volume

Question 3

Hematocrit
It is reported either as a

Answer 3

percentage (%)

liters per liter (L/L)

Question 4

Hct

• Suitable anticoagulants:

Answer 4

Dried Heparin
Ethylenediaminetetraacetic acid (EDTA)

Question 5

is a macroscopic observation of the volume of packed red blood cells in a sample of whole blood, if measured by manual technique.

It may be performed separately or as a part of a complete blood count
(СВС).

Answer 5

hematocrit, or packed cell volume

Question 6

is defined as the ratio of the volume of erythrocytes to that of the whole blood.

It may be expressed in conventional unit as percentage (%), or in S.l. unit as a decimal fraction indicated in liters per liters (L/L).

Dried heparin and ethylene diaminetetraacetic acid (EDTA) are suitable anticoagulants.

Answer 6

Hematocrit

Question 7

Define hct

Answer 7

the ratio of the volume of erythrocytes to that of the whole blood.

Question 8

Gross Examination
• Inspection of the specimen after centrifugation may give a valuable information.
The relative heights of the (3) should be noted

Answer 8

red cell column
buffy coat
plasma column

Question 9

The color of the____ may suggest possible pathologic findings.

Example:
an_______ color is suggestive of increased bilirubin;

a______ suggests presence of hemoglobin (e.g. as occurred during hemolysis).

_____may be suggestive of recent fat-rich meal, or nephrosis (if blood is not collected within 1-2 hours after meal), or presence of abnormal proteins (e.g. hyperglobulinemia, cryoglobulinemia).

Answer 9

plasma

orange or green

pink or red

Cloudy plasma

Question 10

MICROHEMATOCRIT METHOD
Sample:

Answer 10

Capillary (through skin puncture)

Venous Blood (EDTA- anticoagulated)

Question 11

Procedure
1. Fill two capillary tubes approximately three-quarters (or at least_____) with blood. Wipe any excess blood from the outside of the tube.
2. Seal the end of the tuble with the colored ring using non-absorbent clay. Hold the tube horizontally and seal by placing the dry end into the tray with sealing compound at 90-degree angle. The plug should be at least____ long.
3. Balance the tubes in the radial grooves of the______ head with the sealed end away from the center, touching the rubber gasket.
4. Tighten the head cover on the centrifuge and close the top. Centrifuge the tubes at_______ for 5 minutes
5. Determine the hematocrit by using_______. Read the level of RBC packing; do not include the buffy coat when taking the reading.
6. The values of the duplicate hematocrits should agree within_____
7. Report the average of the two results.

Answer 11

5 cm

4mm

microhematocrit centrifuge

10,000 g to 15,000 g (or 10,000-12,000 g [Henry’s])

microhematocrit reading device

1% (0.01 L/L)

Question 12

Normal (hematocrit =_____)
Anemia (hematocrit =_____)
Polycythemia (hematocrit =____)
Dehydration (hematocrit =____)

Answer 12

45%

30%

70%

70%

Question 13

Determining Maximum Packing Time for Microhematocrit

The time to obtain maximum packing of red blood cells should be determined for each centrifuge.
Duplicate microhematocrit determinations should be made using fresh, well-mixed blood anticoagulated with_______

Answer 13

ethylenediaminetetraacetic acid (EDTA).

Question 14

Determining Maximum Packing Time for Microhematocrit

_____specimens should be used, with one of the specimens having a known hematocrit of_______. Starting at___ minutes, centrifuge dupli- cates at 30-second intervals and record results.

When the hematocrit has remained at the same value for two consecutive readings, optimum packing has been achieved, and the second time interval should be used for microhematocrit determinations.

Answer 14

Two

50% or higher

2

Question 15

LABORATORY DETERMINATION OF HEMATOCRIT
Principle:
It is based on the separation of cellular elements of the blood from the plasma by centrifugation.

In both macro- and micromethods, by virtue of density, the… ( arrange from bottom to top)

• The hematocrit is then determined by comparing the volume of the_____ to _____

Answer 15

red blood cells will be at the bottom, the white blood cell and platelets will form a layer on top of the red blood cells, and the plasma will be at the top

red blood cells to the total volume of the whole blood sample.

Question 16

REFERENCE RANGE

Answer 16

MALE: 41.5 - 50.4%
FEMALE: 35.9 - 44.6%

Question 17

SOURCES OF ERRORS
DECREASED

Answer 17

→ Improper sealing
→ Excess EDTA (K3-EDTA lowers PCV more vs. K2-EDTA)
→ Immediately after blood loss
→ Contamination with tissue juice during skin puncture
→ Hemolyzed specimen

Question 18

ERRORS

INCREASED

Answer 18

→ Inadequate centrifugation
→ Inclusion of the buffy coat
→ Presence of poikilocytes
(sickle cells, spherocytes, etc.)
→ Dehydration
→ Clotted specimen
→ Prolonged tourniquet application
→ Delay in reading

Question 19

ERRORS

INCREASED OR DECREASED

Answer 19

→ Specimen not mixed properly
→ Improper use of the micro-hematocrit reader

Question 20

RULE OF THREE
• The rule of three states that:

Answer 20

the value of the hematocrit should be three times the value of the hemoglobin plus or minus 3

Question 21

Used for quality control/validating test results
• This rule only applies to specimens that have normocytic, normochromic RBCs.

Answer 21

Rule of three