BODY FLUIDS

• The analysis of body fluids, including blood cell count and differential cell count, can provide valuable diagnostic information
• This chapter covers cell counting, differential cell counts, and morphology of the commonly received body fluids
• Body fluids discussed in this chapter

  • Cerebrospinal fluid (CSF)
  • Serous or body cavity fluids (pleural, pericardial, and peritoneal fluids)
  • Synovial (joint) fluids
  • Bronchoalveolar lavage (BAL) specimens
• Performing cell counts on body fluids

  1. Observation of color and turbidity

  2. Cell counts (TNC, WBC, RBC)

  3. Differential cell count

  4. Preparing cytocentrifuge slides
• Automated methods for cell counts


  • Overcome limitations of manual methods (time consuming, high variability, poor reproducibility)
  • Dedicated body fluid mode optimizes technologies to account for different cellular composition
• Manual methods for cell counts

  • Using a hemacytometer (glass or disposable)
  • Appropriate dilutions based on turbidity and cell counts
• Performing differential cell counts on body fluids

  1. Identify types of cells (WBCs, tissue cells, malignant cells)

  2. Detect infection, inflammation, hemorrhage, or malignancy
• Cytocentrifuge preparation


  • Concentrates cells into a small area on the slide
  • Minimizes distortion of cells
• Cerebrospinal fluid (CSF)


  Fluid that bathes the brain and spinal column, serves as a cushion, circulating nutrient medium, excretory channel, and lubrication for the central nervous system
• Normal CSF


  • Nonviscous, clear, and colorless
  • Cloudy or hazy appearance may indicate presence of WBCs, RBCs, or microorganisms
• Traumatic tap


  Blood acquired as the puncture is performed
• Pathologic hemorrhage


  Intracranial hemorrhage
• Examining bloody CSF


  1. Centrifuge and observe color of supernatant

  2. Clear, colorless supernatant indicates traumatic tap

  3. Yellowish or pinkish yellow supernatant may indicate subarachnoid hemorrhage
• Normal CSF cell counts

  • 0-5 WBCs/μL and 0 RBCs/μL in adults
  • 0-30 WBCs/μL and 0 RBCs/μL in neonates
• Calculating WBCs added by traumatic puncture

  WBCB x RBCCSF / RBCB = WBCs added by traumatic puncture
• High WBC count in CSF may indicate infective processes like meningitis
• Figure 15.3 Flowchart for Examination of Cerebrospinal Fluid (CSF). RBC, Red blood cell; WBC, white blood cell.
• Dilute, Cytospin slide, Türk (1:2) or (1:20), Report WBC, RBC (1:200), Report RBC
• Characteristics of Cerebrospinal Fluid

  • Traumatic Tap
  • Pathologic Hemorrhage
• Traumatic Tap


  Clear supernatant, Clearing from tube to tube, Bone marrow contamination, Cartilage cells
• Pathologic Hemorrhage


  Colored or hemolyzed supernatant, Same appearance in all tubes, Erythrophages, Siderophages (may have bilirubin crystals)
• True WBCCSF


  CSF WBC hemacytometer count / WBCs added
• Some laboratories have questioned the value of an RBC count on CSF and report only the WBC count
• High WBC count


  May be found in fluid from patients with infective processes, such as meningitis
• WBC counts are much higher (in the thousands) in patients with bacterial meningitis than in patients with viral meningitis (in the hundreds)
• The predominant cell type present on the cytocentrifuge slide (neutrophils or lymphocytes) is a better indicator of the type of meningitis-bacterial or viral
• Elevated WBC counts also may be obtained in patients with inflammatory processes and malignancies
• Normal WBCs in CSF

  Lymphocytes and monocytes
• Neutrophils are not normal in CSF but may be seen in small numbers because of concentration techniques
• When the WBC count is elevated and large numbers of neutrophils are seen, a thorough and careful search should be made for bacteria because organisms may be present in very small numbers early in bacterial meningitis
• In viral meningitis


  The predominant cells seen are lymphocytes, including reactive or viral lymphocytes and plasmacytoid lymphocytes
• Early in the course of viral meningitis, neutrophils may predominate
• Eosinophils and basophils


  May be seen in response to the presence of foreign materials such as shunts, in parasitic infections, or in allergic reactions
• When nucleated RBCs are seen, bone marrow contamination resulting from accidental puncture of the vertebral body during spinal tap should be suspected and reported
• In the case of bone marrow contamination, other immature neutrophils and megakaryocytes also may be seen
• When there is obvious bone marrow contamination, the WBC differential is likely to be equivalent to that of the bone marrow and not that of the CSF
• Ependymal and choroid plexus cells

  Lining cells of the central nervous system, may be seen, are large cells with abundant cytoplasm that stain lavender with Wright stain, most often appear in clumps, and although they are not diagnostically significant, it is important not to confuse them with malignant cells
• Cartilage cells


  May be seen if the vertebral body is accidentally punctured, usually occur singly, are medium to large, and have cytoplasm that stains wine red with a deep wine red nucleus with Wright stain
• Siderophages


  Macrophages that have ingested RBCs and, as a result of the breakdown of the RBCs, contain hemosiderin, appear as large, rough-shaped, dark blue or black granules in the cytoplasm of the macrophage, may also contain bilirubin or hematoidin crystals, indicate a pathologic hemorrhage, appear approximately 48 hours after hemorrhage and may persist for 2 to 8 weeks after the hemorrhage has occurred
• A high percentage of patients with acute lymphoblastic leukemia or acute myeloid leukemia have central nervous system involvement