BODY CAVITY FLUIDS CYTOLOGY
Peter Vajdovich
Szent István University, Faculty of Veterinary Science, Department of Internal Medicine,
Budapest, Hungary, email: Vajdovich.Peter@aotk.szie.hu
Sample handling. Avoid: 1. coagulation (use EDTA containing tubes); 2. waste of cells
(don’t use gel-containing tubes); 3. bacterial contamination (sterility); 4. waste of bacteria
(use special tube for bacterial culture) (Sehlly, 2001); 5. cellular damage (Cowell, 1993).
Laboratory evaluation. 1. organoleptic examination; 2. Rivalta-test (Hartman, 2003); 3.
total nucleated and red blood cell count; 4. direct, unconcentrated smear; 5. specific
gravity (SG); 6. centrifuging (Sehlly, 2001); 7. separating upper layer; 8. total protein
concentration (TP) (O’Brien, 1988); 8. smearing; 9. staining (Cowell, 1993).
Ancillary tests: 1. pH is determined in pericardial effusion to evaluate malignant fluids
(Sehlly, 2001); 2. creatinine/potassium concentration values in fluid are higher than in
serum is suggestive for uroperitoneum (Sehlly, 2001); 3. albumin/globulin (Alb/Glob) ratio
value in effusion of a cat > 0.8, is suggestive for feline infectious peritonitis (FIP) (Sehlly,
2001); 4. serum-effusion albumin gradient (sAlb-eAlb gradient) in abdominal effusion,
with a gradient > or = 1.1 indicating portal hypertension (Pembleton-Corbett, 2000); 5. alpha
1-acid glycoprotein and haptoglobin concentration helps in evaluating FIP (Duthie, 1997);
6. adenosine deaminase activity helps in evaluating FIP (Hirschberger, 1995); 7. total
bilirubin (Br) concentration in peritoneal fluid greater than twice that in serum is
suggestive for bile peritonitis (Sehlly, 2001); 8. lipase and amylase activity in peritoneal
fluid higher than in serum is suggestive for acute pancreatitis (Sehlly, 2001) or small
intestinal rupture; 9. fluid glucose concentration in septic effusion is lower than in blood
(Bonczynski, 2003); 10. fluid lactate concentration in septic effusion is higher than in blood
(Bonczynski, 2003); 11. cholesterol/triglycerol (TG/Chol) ratio less than 1 in the effusion is
suggestive for chylous (Sehlly, 2001); 12. lactate dehydrogenase activity in a non
inflammatory effusion higher than in serum is suggestive for neoplasm; 13. immunology
tests: anti-coronavirus antibody concentration, presence of immune complexes (Hartman,
2003); 14. molecular biology tests: detection of corona viral RNA (Hartman, 2003); 15.
miscallenous tests to distinguish benign from malignant effusions: a) flow cytometry
analysis - DNA ploidy analysis, immunophenotyping; b) hyaluronan production for
lymphoma immunophenotype OHK; c) vascular endothelial growth factor; d) telomerase
enzyme activity; e) fibronectin concentrations; f) AgNOR counts; 16. microbiology tests to
detect infectious disease.
Effusion
type
Transudate
Modified
transudate
Exudate
Color/turbidity
TP g/l
Colorless/clear
< 25
Light yellow to red /clear  25
to cloudy
Apricot to tan/ cloudy
 30
SG g/ml
< 1.017
1.0171.025
 1.025
Nucleated
cell / µl
<1000
 1000
Predominant
cell type
Ly, Mes, Mac
Mon
 5000
Degenerate Ne
(septic),
Non degen. Ne
(non septic)
1. Characteristics of Common Body Cavity Effusions (Sehlly, 2001 with some modifications)
Abbreviations: Ly: small lymphocyte, Ne: neutrophil granulocyte, Mac: macrophage, Mes:
mesothelial cell, RBC: red blood cell, PLT: platelet, Mon: mononuclear cells in mixed
population
Specific conditions (often classified as exudates by TP, SG and nucleated cell count)
Effusion type
Color/ turbidity
Predominant cell type
Chylous
White/opaque
Acute: Ly, Chronic: Ne, Mon
TGChol
PseudoWhite/opaque
Ne, Mon
chylous
CholTG
Neoplastic
Light yellow to apricot/ clear to Mes and neoplastic cells
cloudy
Hemorrhagic
Pink to red/ cloudy
RBCs, Ne, Ly, acute bleeding –
PLTs,
chronic
bleeding
–
erythrophagocytosis, Mes, Mac
Bilious
Dark yellow or brown or green / Ne, Mon with bile pigment
opaque
(fluid Br  serum Br)
FIP
Colorless to yellow / transparent to Mac, Ne (karyopicnosis), Ly, Mes
cloudy
2. Characteristics of Specific Body Cavity Effusions (Sehlly, 2001 with some modifications)
Microscopic evaluation helps in differentiating inflammatory and non inflammatory fluids. If
the fluid diagnosed as inflammatory, it can be septic or non septic. If diagnosed as non
inflammatory it should be evaluated if it is neoplastic or reactive. The latter is often difficult
as hyperplastic mesothelial cells resemble to malignant neoplastic cells (Baker, 2000).
Sensitivity of cytology analysis of malignant tumors in effusion was low (64% for dogs, 61%
for cats), and the specificity was high (99% for dogs, 100% for cats) (Hirschberger, 1999), in
pericardial fluid specificity and sensitivity values were less (Shelly, 2001).
References
Baker R., Lumsden J.H., 2000. Color atlas of Cytology of the Dog and Cat. Mosby, Inc. St.
Louis pp 159- 165.
Bonczynski J.J., Ludwig L.L., Barton L.J., Loar A., Peterson M.E., 2003. Comparison of
peritoneal fluid and peripheral blood pH, bicarbonate, glucose, and lactate concentration as
a diagnostic tool for septic peritonitis in dogs and cats. Vet Surg. 32(2):161-6.
Cowell R.L., Tyler R.D. and Meinkoth J.H., 1993. Abdominal and Thoracic Fluid. In: Cowell
R.L., Tyler R.D. (ed) Diagnostic Cytology of the Dog and Cat. American Veterinary
Publications, Inc. Goleta pp 151-166.
Duthie S., Eckersall P.D., Addie D.D., Lawrence C.E., Jarrett O., 1997. Value of alpha 1-acid
glycoprotein in the diagnosis of feline infectious peritonitis. Vet Rec. 141(12):299-303.
Hirschberger J., Koch S.,1995 Validation of the determination of the activity of adenosine
deaminase in the body effusions of cats. Res Vet Sci. 59(3):226-9.
Hartmann K., Binder C., Hirschberger J., Cole D., Reinacher M., Schroo S., Frost J., Egberink
H., Lutz H., Hermanns W., 2003. Comparison of different tests to diagnose feline infectious
peritonitis. J Vet Intern Med. 17(6):781-90
Hirschberger J, DeNicola D.B, Hermanns W, Kraft W., 1999. Sensitivity and specificity of
cytologic evaluation in the diagnosis of neoplasia in body fluids from dogs and cats. Vet
Clin Pathol. 28(4):142-146.
O’Brien, P.J., and Lumsden J.H., 1988. The cytologic examination of body cavity fluids.
Semin. Vet Med Surg (Small Anim) 3:140-156.
Pembleton-Corbett J.R., Center S.A., Schermerhorn T., Yeager AE., Erb H.N., 2000. Serumeffusion albumin gradient in dogs with transudative abdominal effusion. J Vet Intern Med.
14(6):613-8.
Shelly S.M., 2001. Body Cavity Fluids. In: Raskin R., Meyer D.J. (ed) Atlas of Canine and
Feline Cytology. WB. Saunders Co., pp 187-205.