RED BLOOD CELL INDICES INTERPRETATIONS AND CALCULATIONS
IDENTIFICATION: The average volume of Red Blood Cells
MCV
IDENTIFICATION: This substance is used as a fixative during manual staining of peripheral blood smears to preserve cellular morphology.
Methanol
Manual WBC counting is commonly performed using which piece of equipment?
A. Coulter counter
B. Spectrophotometer
C. Hemacytometer
D. Flow cytometer
C. Hemacytometer
Which dilution is typically used for a manual white blood cell count?
A. 1:10
B. 1:50
C. 1:100
D. 1:20
D. 1:20
According to Rodak, manual WBC counts are necessary when:
A. The blood sample is clotted
B. Automated counts exceed the instrument’s linearity
C. Platelet counts are low
D. RBC indices are abnormal
B. Automated counts exceed the instrument’s linearity
IDENTIFICATION: What is the normal range for MCHC?
Unit: g/dL (grams per deciliter)
Normal adult range: 32 – 36 g/dL
IDENTIFICATION: This type of stain is a polychrome Romanowsky stain that contains methylene blue and eosin, allowing simultaneous visualization of nuclei and cytoplasmic components.
Wright or Wright-Giemsa stain
Which hemacytometer chamber is commonly used for manual WBC counting?
A. Fuchs-Rosenthal chamber
B. Thoma chamber
C. Levy chamber with improved Neubauer ruling
D. Petroff-Hausser chamber
C. Levy chamber with improved Neubauer ruling
Which diluting fluid is commonly used to lyse RBCs while preserving WBC nuclei?
A. Normal saline
B. Turk’s solution
C. EDTA
D. Wright stain
B. Turk’s solution
During microscopic examination, which counting method ensures systematic coverage of the chamber?
A. Random scanning
B. Spiral method
C. Battlement or serpentine method
D. Zigzag method
C. Battlement or serpentine method
IDENTIFICATION: What is the correct formula for MCV?
MCV (fL) = (Hematocrit % / RBC count [millions/µL]) × 10
ENUMERATION: Enumerate at least 2 features of a well-made blood smear.
1.Two-thirds or three-fourths of the slide.
2.Finger shaped
3.Visible lateral edge
4.Smooth, without irregularities, holes, or streaks.
5.Thin portion shows a rainbow appearance.
6. The wholw drop of blood is picked up and spread.
What is the acceptable difference between the total WBC counts on each side of the hemacytometer?
A. Less than 5%
B. Less than 10%
C. Less than 15%
D. Less than 20%
B. Less than 10%
Which cells are lysed by the diluting fluid during a manual WBC count?
A. Platelets
B. White blood cells
C. Nucleated red blood cells
D. Non-nucleated red blood cells
D. Non-nucleated red blood cells
Give at least 1 counting rule for cells touching the borders of the ruled area in a hemacytometer
Count cells touching the top and left borders
Do NOT count cells touching the right and bottom borders
This rule prevents double counting of cells
Ensures standardization and reproducibility of results between counts
CALCULATIONS: A total of 92 WBCs is counted in Chamber 1 and 100 WBCs in Chamber 2 using a 1:20 dilution.
Calculate the average WBC count to be reported in ×10³/µL.
WBC = 4.8 × 10³ /µL
IDENTIFICATION: This microscope objective is primarily used to examine nuclear details of white blood cells and to perform the actual WBC differential count.
100× oil immersion objective
This is the ideal area of the blood smear where red blood cells have central pallor, are evenly distributed, and do not overlap—making it optimal for detailed examination.
Monolayer (optimal examination area)
Which characteristic must a WBC diluting fluid have to prevent interference during counting?
A. Isotonic
B. Hypertonic
C. Hypotonic
D. Buffered
C. Hypotonic
Which of the following is the PRIMARY purpose of performing a manual white blood cell count?
A. To replace automated hematology analyzers
B. To validate electronic counts and serve as a backup method
C. To identify abnormal hemoglobin variants
D. To measure red blood cell indices
B. To validate electronic counts and serve as a backup method
Patient Data: MCV = 25 fL MCHC = 36 g/dL
Question: Based on the RBC indices, how would you classify the red blood cells?
A. Microcytic, hypochromic
B. Microcytic, normochromic
C. Normocytic, normochromic
D. Macrocytic, hyperchromic
ENUMERATION: Enumerate at least two reasons why a smear that is too thick is considered unacceptable.
A. Chipped or rough edge
B. Hesitation in forward motion
C. Pushed too quickly
D. Drop of blood too small
E. Drop of blood did not spread across the width of the slide
F. Dirt or grease on the slide; may also be due to elevated lipids
G. Uneven pressure
H. Time delay
What is the formula for MANUAL WBC COUNTING?
WBC Count/µL = (Total Cells Counted × Dilution Factor) / (Area Counted in mm² × Depth in mm)
Why must red blood cells be lysed during a manual white blood cell count?
Red blood cells are far more numerous than white blood cells
Intact RBCs would obscure the visual field, making WBC counting inaccurate
WBC diluting fluids lyse non-nucleated RBCs while preserving WBC nuclei
Lysis allows clear visualization and accurate identification of WBCs under the microscope
Prevents false elevation or interference in the WBC count
Enumerate 4 simple steps of the manual wbc counting
STEP 1: SPECIMEN DILUTION
STEP 2: CHARGING OF HEMACYTOMETER
STEP 3: MICROSCOPY
STEP 4: REPORTING