Cerebrospinal Fluidbody Fluid Cell Count And Differential

Principle

The examination of the cellular component of body fluids is an important part of total body fluid testing. Cell counts are performed in a counting chamber. Cere-brospinal fluid (CSF), synovial fluids, and serous fluids of the pleural, pericardial, and peritoneal cavities all have characteristic cellular elements, which often change with disease in predictable patterns. Cell counts and cell morphology are key elements in identifying abnormalities within each of these systems. The methods outlined here present a unique method and calculation reference for performing fluid counts. For the standard cell counting formula, refer to the Unopette method for manual cell counts on page 311.

Reagents and Equipment

1. Saline

2. Slide stainer

3. Phase microscope

4. Neubauer hemacytometer with coverslip

5. Petri dish

c. 1.0 volumetric d. 10.0 volumetric

7. 12 X 75-mm plastic tubes

8. Cytospin

9. Disposable Cytofunnels with white filter attached

10. Bovine albumin, 22%

11. Hyaluronidase

12. Plain microhematocrit tubes

13. Crystal violet diluent

Specimen Collection and Storage

Cerebrospinal Fluid

1. Collected in the sterile plastic tubes from the spinal tray. The laboratory accepts tubes 1 and/or 4.

2. Tube 4 is the preferred tube because it is least likely to be contaminated with blood.

3. CSF cell counts should be performed within 1 hour of receipt in the laboratory because cells lyse on prolonged standing and accurate counts become impossible.

Synovial and Serous Fluids (Pleural, Pericardial, and Peritoneal)

1. Fluids should be collected in a heparinized tube or EDTA tube.

2. Perform testing within 4 hours.

3. The addition of hyaluronidase to the fluid may reduce the viscosity of synovial fluid.

314 PartV • Laboratory Procedures

Quality Control

The College of American Pathologists has removed daily quality control for all body fluids. Each laboratory receives proficiency testing at least two times a year from their proficiency program.

Procedure

Cell Counting Method

1. Based on the gross appearance of the fluid, dilute the specimen by one of the following methods:

a. METHOD A (clear or slightly cloudy fluid) Dilute 1:2 with crystal violet diluent (0.2 mL specimen + 0.2 mL diluent)

b. METHOD B (moderately cloudy fluid) Dilute 1:11 with saline (0.1 mL specimen + 1.0 mL saline) using a volumetric pipette. Then dilute 1:2 with crystal violet diluent (0.2 mL of 1:11 dilution + 0.2 mL diluent)

c. METHOD C (very cloudy or bloody fluid) Dilute 1:101 with saline (0.1 mL specimen + 10.0 mL saline) using a volumetric pipette. Then dilute 1:2 with crystal violet diluent (0.2 mL of 1:101 dilution + 0.2 diluent)

2. Using a plain microhematocrit tube, fill each side of the hemacytometer with the dilution. Place the hemacytometer in a premoistened

Petri dish. Allow the cells to settle for 3 to 5

minutes in the Petri dish.

a. Place the hematocytometer in the phase microscope. Determining the number of squares to be counted depends on the initial viewing of the fluid on the hematocy-tometer chamber under the microscope. This is the judgment of the technologist/ technician.

b. Using the X20 or X40 objective, count the WBCs and RBCs on each side. Now enter the WBC and RBC of each dilution in the CSF/body fluid worksheet (see Table 20.9).

c. Combine the two totals and take the average for the WBC and RBC counts, which must agree within 20%. If this criterion is not met, reload the chamber and redo the counts.

d. The gross appearance of non-CSF fluid will determine whether an RBC dilution is needed. If the fluid is cloudy and bloody, then the red cells are too numerous to count; report RBCs as "TNTC."

e. Tables 20.8 and 20.9 offer a unique calculation reference for fluids. Once a dilution is determined and counts are performed for various fluids, then data can be plugged into these ready reference tables for a quick calculation of a final result. For example:

Dilution

No. of Squares

No. of Cells

Average No.

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Responses

  • Amanuel
    What is the diluent for cloudy body fluids?
    3 months ago

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