Page 607 - Clinical Hematology_ Theory _ Procedures ( PDFDrive )

CHAPTER 29 ■ Body Fluid Analysis 591

PROCEDURE FOR DIFFERENTIATION OF CELLS IN SPINAL FLUID

PRINCIPLE increased cellular ragility. In addition, cellular size can be

Slide preparations are routinely per ormed on all CSF speci- distorted by cytocentri uge preparation. Cells in the interior

mens. I the total leukocyte count exceeds the normal value, o a specimen may be smaller and have a denser nucleus than

a di erential count is usually per ormed. do cells at the periphery.

REAGENTS, SUPPLIES, AND EQUIPMENT CLINICAL APPLICATIONS

1. Conical centri uge tubes Normal CSF is crystal clear and colorless. Gross blood may

2. Microscope slides and Pasteur pipettes be observed in traumatic tap specimens or in cases o patho-

3. Centri uge logical bleeding caused by spontaneous subarachnoid hem-

4. Methylene blue or Wright’s stain orrhage or intracerebral hemorrhage.
Xanthochromia may be indicative o the pathological con-

PROCEDURE dition subarachnoid hemorrhage, i the erythrocytes have

Te sediment to be examined should be prepared using a been present long enough to hemolyze.

cytocentri uge, ltration, or sedimentation technique. T e Clotting can be caused by the presence o peripheral

cytocentri uge is the pre erred method or concentrating blood, increased protein, or gel ormation on standing due

CSF specimens. I these methods are not available, an older to an increased brinogen content.
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alternative can be used. urbidity is seen i at least 200 leukocytes × 10 /L, or 400
erythrocytes × 10 /L, or microorganisms are present. Increased
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ALTERNATIVE METHOD FOR SEDIMENT segmented neutrophil counts classically suggest bacterial

PREPARATION in ection; however, increased PMNs can be rom in ectious

1. Pour 1 to 2 mL o resh undiluted spinal f uid into a coni- and nonin ectious agents. In ectious disorders include bacte-

cal centri uge. Balance the centri uge and centri uge at rial meningitis, viral meningoencephalitis (the rst ew days o

2,500 rpm or 10 minutes. in ection), early tuberculosis, and mycotic meningitis. Aseptic

2. Following centri ugation, remove the supernatant f uid meningitis can exist in cases in which the septic ocus is adja-

with a Pasteur pipette and either save at 4°C to 6°C or cent to the meninges. Nonin ectious causes o increases in

reeze or other analyses, i needed. Resuspend the pre- PMNs include reaction to CNS hemorrhage (3 to 4 days a er-

cipitate by gently tapping the tip o the centri uge tube ward), injection o oreign substances such as lidocaine into

against the palm o the hand. the subarachnoid space, and leukemic in ltration.

3. rans er a small drop o the resuspended sediment onto a glass Increased numbers o lymphocytes are typically asso-

slide and smear out as a blood smear. Air-dry thoroughly. ciated with viral in ections but may be seen in a variety o

4. Stain with either methylene blue or Wright’s stain. T e disorders. T ese disorders include viral meningoencephali-

methylene blue stain is pre erred and should be applied to tis, ungal meningitis, syphilitic meningoencephalitis, and

the smear or approximately 12 minutes. Gently wash o partially treated bacterial meningitis. Nonin ectious causes

the stain with distilled water. o increased lymphocyte numbers include conditions such

5. Allow the smear to air-dry. Examine using the 100× (oil as multiple sclerosis.

immersion) objective. Count the number o di erent cells Other types o cells are rarely encountered. Plasma cells

observed on a total count o 100 leukocytes. are normally absent. Eosinophils may be increased because
o causes similar to those o an increase in PMNs; increased

REPORTING RESULTS basophils can be seen in chronic basophilic leukemia, which

Few mononuclear cells (lymphocytes and monocytes) and a involves the meninges; and monocytes may be seen in leuke-

rare ependymal cell are considered normal ndings. mic in ltration o the meninges and in ectious states.

PROCEDURE NOTES ASSOCIATED FINDINGS

Sources of Error Glucose and protein values are important to correlate with

Arti actual distortion o cells prepared with a cytocentri uge gross and microscopic ndings in the CSF. In general, a

can lead to misidenti cation. Specimens should be prepared decreased glucose level in the CSF in the presence o a nor-
with a cytocentri uge, but these preparations may demon- mal blood glucose level indicates bacterial utilization o glu-

strate arti acts. Portions o ragmented nuclei or cytoplasm cose. In addition, an elevated total protein concentration is
can be seen. In addition, cells may assume distorted shapes, also suggestive o an inf ammatory reaction or a bacterial

granules may become localized in the cytoplasm, and vacu- in ection. A viral in ection will not have a dramatic e ect on
oles may appear in the cytoplasm. Abnormal cells are more CSF glucose levels and may not a ect the total protein level

prone to exhibit arti actual disruptions, perhaps because o signi cantly.