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This information is provided by
Provet for educational purposes only.
You should seek the advice of your
veterinarian if your pet is ill as only he or she can correctly advise on the
diagnosis and recommend the treatment that is most appropriate for your pet.
Accumulation of fluid within a body
cavity is a common clinical finding which may be associated with a variety of
diseases. Characterisation of the fluid helps with the differential diagnosis. Aspiration
and laboratory identification of fluid from a body cavity is a commonly
used diagnostic aid. The following table (modified after
MacWilliams et al, Proceedings NAVC Jan 2000) summarises the different
fluid characteristics and differential diagnosis :
|
Normal |
Transudate |
Exudate |
Volume of fluid |
Very small amount |
Large amount |
Variable amount |
Appearance of fluid |
Clear and colourless |
Clear and colourless or red-tinged |
Turbid and white-yellow. |
Protein content |
<2.5 g/dl |
<2.5 g/dl |
>3.0g/dl |
Total number of nucleated cells (TNCC) |
<3000 / mL |
<1500 / mL |
>5000 /mL |
Cell types present |
Mixed cells: Lymphocytes Macrophages Mesothelial
cells Monocytes |
Mixed cells: Lymphocytes Macrophages Mesothelial cells
Monocyte |
Inflammatory cells: Eosinophils Lymphocytes Macrophages
Neutrophils (majority) |
Cause 1 |
NA |
Hypoproteinaemia |
Inflammation |
Cause 2 |
NA |
Venous or lymphatic obstruction/congestion |
Organ perforation or rupture |
Cause 3 |
NA |
|
Neoplasia with inflammation or necrosis |
Hypoproteinaemia (serum albumin less than 1.0g/dl) may occur with:
- Severe protein loss :
- Intestinal malabsorption
- Proteinuria
- Liver disease
- Overhydration
Venous or lymphatic obstruction/congestion may be due to :
- Cardiac Failure - right heart failure. Fluid is clear to red-tinged with
increased protein (2.5-4.5 g/dl) and only a slightly increased TNCC (neutrophils,
lymphocytes and macrophages). This fluid is called a modified transudate.
- Lymphangiectasia
- Atelectasis
- Obstruction due to a mass
Inflammation may be due to infection caused by :
- Bacteria
- Fungi
- Protozoa
- Viruses eg Feline Infectious Peritonitis. Clear to yellow-orange
fluid. Turbid. Total nucleated cell count (TNCC) 500-20000/
mL. Protein content 3.5-7.0 g/dl
and by
- Fluid leakage from organs
- Neoplasia .
- Lymphoma results in white to yellow, clear or turbid fluid
accumulation. TNCC varies. Large hyperchromatic lymphoblasts with
evidence of mitosis are present.
Fluids originating from a perforated or ruptured organ include :
- Haemorrhage - trauma to blood vessels, thrombocytopenia, clotting
defects
- blood may appear in a sample due to contamination during collection
of the fluid
- If fluid has a high platelet count - blood presence is most likely
due to contamination or active haemorrhage is going on.
- Post-trauma a large number of red blood cells and few leukocytes are
present.
- Gastrointestinal perforation - leakage of secreted fluids,
digestive enzymes, chyme or faeces lead to peritonitis.
- Chyle - milky-white fluid sometimes with blood tinge. Chyle
contains higher triglyceride and lower cholesterol than serum. Causes :
- Obstruction of thoracic duct - neoplasia or granulomas
- Injury leading to rupture or perforation of the thoracic duct. May
be associated with diaphragmatic hernia.
- Cardiovascular disease
- Vomiting
- Chronic coughing
- Bile - causes peritonitis. Yellow-orange to green fluid and
turbid fluid.
- Urine - ruptured bladder, ureters, renal injury. Azotaemia may be
present. Little inflammation caused. Fluid is clear, light yellow and
contains few cells, unless inflammation was present before rupture.
- Ruptured gravid uterus
- Ruptured uterus with pyometra
- Ruptured cysts
Last updated : October 2013
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