Manual Sahl Pipette Method

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c. Physiologic conditions, with counts as high as 15,000/mm³. Some of these may occur as follows:

(1) in the newborn

(2) during late pregnancy

(3) during labor

(4) accompanying severe pain

(5) after exercise or meals

(6) after cold baths

(7) during severe emotional upset

2. Leukopenia (abnormally low count). This may be caused by:

a. Severe or advanced bacterial infections, such as typhoid, paratyphoid, and sometimes tularenia, or when the bacterial infection has been undetected for a period of time as with chronic beta streptococcal infections of the throat.

b. Infections caused by viruses and rickettsiae, such as measles, rubella, smallpox (until the 4th day), infectious hepatitis, psittacosis, dengue, tsusugamushi fever, and influenza (when it may fall to 1,5000/mm³, or shift to leukocytosis if complications develop).

c. Protozoal infections (such as malaria) and helminthic infections (such as Trichinosis). In malaria, slight leukocytosis may develop for a short time during paroxysm, but shortly after its onset leukopenia ensues. With trichinosis there may be leukocytosis with an increase in eosinophils (as high as 50 to 70 percent).

d. Overwhelming infections when the body’s defense mechanism breaks down

e. Anaphylctic shock

f. Radiation

Manual Sahl Pipette Method

The materials listed below are required to perform a white blood cell count using the manual Sahl pipette method:

Heacytometer set

Microscope with lamp

White cell pipette

Suction tube

Laboratory chits

White cell diluting fluid. This may be either of two acids. The acid ruptures the red cells, leaving the white cells intact.

These acids are:

Dilute hydrochloric acid. Prepare this by mixing 1 ml of concentrated hydrochloric acid with 99 ml of water. POUR ACID INTO WATER.

Glacial acetic acid 2 ml

1 percent aqueous solution of gentian violet 1 ml

Distilled water 97 ml

The gentian violet is not necessary, but by staining the nucleus, it makes the cells more refractive and helps to make an accurate count.

Four plain glass slides to prepare smears for differential count

hand held counter

Procedure

1. Draw well-mixed anticoagulated venous blood or fingertip blood to the 0.5 mark on the white cell pipette.

2. Observing the same precautions as for red cell count, draw diluting fluid to the 11.0 mark.

3. Shake the pipette for 3 minutes. Do not shake along the long axis. (See figure 6-5.)

4. Load the counting chamber, using the same technique as for the red cell count.

5. Count the white cells with the low-power lens in each of the four large corner fields (A, B, C, and D, in figure 6-8). Use subdued lighting. Go clockwise around the counting chamber; that is, from field A to field B to field C to field D. For convenience each field is divided into 16 smaller squares. Starting with the small square in the upper left corner of the field, count the cells in each square in the top row, moving across the field to the right, then drop down one row of squares and work back to the left, as indicated by the arrow in figure 6-8. Remember the rule for counting cells: COUNT THE CELLS TOUCHING THE BORDER LINES AT THE TOP AND ON THE LEFT. DO NOT COUNT