02 LAB: HEMATOCRIT DETERMINATION & RULE OF THREE Flashcards
The volume of packed RBC that occupies a given volume of whole blood after centrifugation of a blood sample
Hematocrit
In Adam’s microhematocrit method, the capillary tubes are filled up to ___ with blood
3/4
In Henry’s microhematocrit method, the capillary tubes are filled up to ___ with blood
2/3
Length of capillary tubes
7-7.5 cm
Bore size of capillary tubes
1.2 mm
A non-heparinized capillary tube has a ___ colored ring
blue
A heparinized capillary tube has a ___ colored ring
red
The capillary tube is placed into the tray with sealing compound at ___-degree angle
90
The plug of the capillary tube should be atleast __ mm long
4
In the microhematocrit centrifuge, the clay ends should face ___ from the center
away
The capillary tube is centrifuged at ___ for ___
10 000 g - 15 000 g
4-5 mins
Reference range of hematocrit for males
40-54%
Reference range of hematocrit for females
35-49%
T/F: the estimation of hemoglobin and RBC is possible on the bases of hct value under normal circumstances
T
Under normal circumstances, 1% hct = ___ g/dL hgb or ___ RBC/cumm
0.34 g/dL
107 000 RBC/cumm
The improper sealing of the capillary tube causes a ___ hematocrit reading as a result of ___ of blood during centrifugation
decreased
leakage
An increased concentration of anticoagulant ___ the hematocrit reading
decreases
A decreased or increased result may occur if the specimen was not ___ properly
mixed
Insufficient centrifugation or a delay in reading results after centrifugation causes hematocrit readings to ___
increase
The buffy coat of the specimen should not be included in the hematocrit reading because this falsely ___ the result
elevates
Source of error:
amount of plasma that still remains in the RBC portion after the microhematocrit has been spun
trapped plasma
Trapping of the plasma causes the microhematocrit to be ___ higher than the value obtained using automated instruments that calculate the hematocrit
1-3%
How is hematocrit computed?
RBC X MCV
A temporarily low hematocrit reading may result immediately after a ___ because plasma is replaced faster than are the RBCs
blood loss
The fluid loss associated with dehydration causes a ___ in plasma volume and falsely ___ the hematocrit reading
decrease
increases
The introduction of interstitial fluid from a skin puncture of the improper flushing of an IV catheter causes ___ hematocrit readings
decreased
The length of the Wintrobe tube
11.5 cm
Size of the bore of Wintrobe tube
3 mm
Calibration of Wintrobe tube used for ESR
0-10 (red)
Calibration of Wintrobe tube used for hematocrit
10-0 (white)
The anticoagulant of choice in Wintrobe tube is ___
double oxalate
In the Wintrobe method of hematocrit determination, the tube is centrifuged at ___ for ___
3 000 rpm
30 mins
In the Wintrobe method of hematocrit determination, the hematocrit is computed by what formula?
height of packed RBC/ height of whole blood used
The Haden’s modification of hematocrit determination uses ___ as anticoagulant
1.1 sodium citrate in distilled water
The Haden’s modification of macrohematocrit method uses what formula to determine hematocrit concentration?
volume of packed RBC x 20
In the Haden’s modification, if the blood used is less than 5 mL, the formula to use is ___
(volume of packed RBC/ volume of whole blood used) x 100
In the Von Allen method of macrohematocrit method uses ___ as an anticoagulant of choice
1.6% sodium oxalata in distilled water
This macrohematocrit method uses a tube with bulb and calibration of 1-10 cm (10-100 mm)
Von Allen Method
In the Von Allen method, the capillary tube is centrifuged at ___ for ___
2 500 rpm
15-30 mins
In the Sanford-Magath macrohematocrit method, the anticoagulant of choice is ___
1.3% sodium oxalate
In the Sanford-Magath macrohematocrit method, the tube is calibrated at ___ per division
1 mm
In the Sanford-Magath macrohematocrit method, the tube is about ___ long and a ___ mouth
5 inches
funnel-like
In the Sanford-Magath macrohematocrit method, the tube is centrifuged at high speed for ___
15 mins
In the Bray’s macrohematocrit method, the anticoagulant of choice is ___
heparin
In the Bray’s macrohematocrit method, the tube should be ___-bottomed and calibrated on both sides, similar to ___ tube
flat
Wintrobe
In the Bray’s macrohematocrit method, the calibration is ___, each division is ___, and the capacity is ___
10-50 mm
1 mm
5 mL
In the Bray’s macrohematocrit method, the tube is left at a vertical position for ___
1 hour
According to the rule of three, hemoglobin is computed as ___
RBC X 3
According to the rule of three, hematocrit +/- 3 is computed as ___
hemoglobin x 3
The rule of three only applies to specimens that have ___, ___ RBCs
normocytic
normochromic
