Effusion Dx Flashcards
What is an effusion?
- ^ amount fluid in thoracic/abdo cavity
- not disease, indicates pathologic process
- BUT fluid may be only cause of clinical signs
What sample tube should effusions be collected into?
- EDTA for counts, cytology and protein
- Serum (plain) for biochem and culture
Give 4 main things that can be analysed in effusions
- TNCC (total nucleated cell count)
- Cell ID morphology
- Protein concentration
- Other (enzymes eg. amylase and lipase, urea and creatinine, cholesterol and TGs)
What should normal fluid be like in small animals>
- Low volume (2ml) - cannot tap if healthy animal
- clear, straw coloured
- TP: 25-30g/l
- TNCC: <3x10e9/l (very difficult to find cells under microscope)
- mesothelial cells/macrophages
What 4 factors affect movement of fluid in/out of pleural/peritoneal cavities? (ie. all pathologies -> effusion act via one of these)
- Hydrostatic pressure
- Colloid osmostic pressure (albumen)
- Permeability of capillary wall
- Lymph drainage
What are the 3 classifications of effusions based on TNCC and TP? What else may an effusion be?
- Transudate (passive, due to hydrostatic:oncotic pressure imbalance)
- Modified transudate
- Exudate (active)
> may also be haemorrhage
HOw may a transudate be identified?
> low protein and cellularity, clear like water
- SG <0.5x10e9/l (difficult to find cells)
- mesothelial cells/macrophages/low no.s non-degenerate neutrophils
What is the most common cause of transudate? what else may be involved?
- v colloid osmotic pressure (hypoalbumenaemia) 2* to glomerular disease, hepatic disease, GI loss (usually also v globulins)
- hypoalbumenaemia alone ONLY able to cause transudate if extremely severe ( ^ water retention RAAS system
How may hepatic cirrhosis lead to transudate formation?
- Portal hypertension 2* to hepatic fibrosis/cirrhosis
- 2* collateral circulation forms
- local production of vasodilators (NO)
- splanchnic casodilation, v blood flow
- compounded by renal retention of Na [RAAS] and hypertension generally
=> end result: expansion of plasma volume, leakage of low protein lymph from intestines
What effusion occours with pre-hepatic congesttion?
Low protein
Describe a modified transudate
- yellow - serosanginous, cloudy
- TNCC 0.3-7x10e9/L
- SG 1.018 - 1.030
- protein variable 25-50g/l
- mesothelial cells, macrohpages, non-degenerate neutrophils
What is true modified transudate usually seen due to?
> chronic heart failure/ cardiac disease -> ^ hydrostatic pressure (esp in hepatic sinusoids) -> leakage of protein rich lymph from liver. Also Na+ and fluid retention.
chylous effusion
lymphatic obstruction - neoplasia
chronic hepatic venous obstruction
- though other fluids may be lumped into this group!
Describe exudate. Why does this occour?
- due to inflammation (High TNCC and protein)
- Turbid - red/yellow/white, PUSS
- SG >1.018
- TP >30g/L
- TNCC >3x10e9g/L
- DOminance of neutrophils (degenerate/normal), macrophages, some lymphocytes and easinophils possibly
Give 3 causes of exudates
- Inflammation of pleural/abdominal cavities or linings
- septic OR non-septic - Long standing modified transudate becomes exudate as causes inflammation
- Neoplasia - necrotic foci etc. -> inflammatino
How would a septic exudate be distinguished from a non-septic exudate? Give an eg. of a non-septic exudate
Non-Septic - non-degenerate neutrophils - no bacteria - eg. FIP (viral) Septic - degenerate neutrophils - intracellular bacteria