Diagnosis of effusions

Question 1

What is an effusion?

Answer 1

increased amount of fluid (abdominal or thoracic cavity), not a disease but a sign of a pathologic process, may be the only cause of clinical signs

Question 2

Why analyse an effusion?

Answer 2

• differentiate fluid types –> further diagnostics and management
• identify fluid types with a more specific aetiology
• definitive diagnosis

Question 3

Into which tubes do you collect fluid?

Answer 3

• into EDTA for counts, cytology and protein

- into serum/plain tube for biochemistry or culture

Question 4

What are the 3 most important things looked at on fluid analysis?

Answer 4

• total nucleated cell count (TNCC)
• cell identification and morphology
• protein concentration

Question 5

What else can be looked at?

Answer 5

• enzymes (amylase, lipase)
• urea and creatinine
• cholesterol and Tg

Question 6

Describe normal fluid (volume, colour, protein, nucleated cell count, other cells)

Answer 6

low volume
clear, straw colour
total protein: 25-30g/L
nucleated cell count <3*10^9/L
-mesothelial cells and macrophages

Question 7

4 factors regulating fluid movement

Answer 7

• hydrostatic pressure
• collod osmotic pressure (albumin)
• capillary wall permeability
• lymphatic drainage

Question 8

How are transfusions classified? 3

Answer 8

TNCC, total protein and cell morphology/size

Question 9

3 types of effusion

Answer 9

transudate, modified transudate (less so), exudate.

Also haemorrage

Question 10

Describe transudate (colour, protein, nucleated cell count, other cells)

Answer 10

low protein and cellularity
clear 
S.G. < 25g/L
TNCC <0.5 * 10^9/L
mesothelial cells, macrophages, low numbers of non-degenerate neutrophils

Question 11

Causes - transudates

Answer 11

Several theories:

• decreased colloid osmotic pressure - hypoalbuminaemia (classic simplest theory but rarely occurs as often alterations in hydrostatic pressure too). This may occur secondary to glomerular disease, hepatic disease or GI loss (e.g. PLE). Most animals with abdominal transudates have albumin in range of 15-25g/L so other factors are involved.
• RAAS activation

Question 12

What exudate do hepatic cirrhosis and portal hypertension cause?

Answer 12

transudate

Question 13

Describe pathogenesis of transudate formation secondary to hepatic fibrosis/cirrhosis

Answer 13

Prolonged portal hypertension and formation of secondary collateral circulation –> local production of local vasodilators (NO), leads to splanchnic vasodilation and decreased effective BF, compounded by renal secretion of sodium via RAAS and generalised hypertension –> expansion of plasma volume and leakage of low protein lymph from the intestines

Question 14

Desribe modified transudate (colour, protein, nucleated cell count, other cells)

Answer 14

yellow to serosanguinois, cloudy
TNCC 0.3-5.5 * 10^9/L (up to 7*)
SG 1.018 to 1.030
protein variable 25-50g/L
mesothelial cells, macrophages, non-degenerate neutrophils, small lymphocytes

Question 15

Causes of modified transudates? 3

Answer 15

Cardiac disease
chylous effusion
lymphatic obstruction (neoplasia)

Question 16

Explain pathogenesis of how cardiac diseae leads to modified transudate formation

Answer 16

chronic passive congestion –> increased hydrostatis pressure, especially in hepatic sinuosids, leakage of protein rich lymph from liver, Na and fluid retention.

Question 17

Desrcibe exudate (colour, protein, nucleated cell count, other cells)

Answer 17

high TNCC and protein
turbid -red, yellow, white
SG > 1.018
total protein >30g/L
TNCC >3.0 *10^9/L
neutrophils (Degenerate or not), macrophages, (lymphocytes and eosinophils)

Question 18

Causes - exudates 3

Answer 18

• inflammation of pleural/abdominal cavities or their linings (septic vs non-septic)
• long-standing modified transudate
• neoplasia

Question 19

Distinguish non-septic exudate from a septic exudate

Answer 19

NON-SEPTIC: non-degenerate neutrophils, no bacteria, FIP

SEPTIC: degenerate neutrophils and intracellular bacteira

Question 20

Describe the fluid found in FIP

Answer 20

TNCC variable (0.2-23 * 10^9/L)
non-degenerate neutrophils and macrophages
high protein (35-80g/L)
albumin: globulin >0.81 on fluid - highly correlated
positive coronavirus (higher titres more suggestive in dry FIP (>640), may be 0->1280 with wet
alpha-1-acid glycoprotein (APP) elevation >1500microg/mL

FLUID MAY BE CLASSIFIED AS MODIFIED EXUDATE OR TRANSUDATE DEPENDING ON TNCC

Question 21

Describe a healthy neutrophil

Answer 21

• dense chromatin fibres
• intact membrane
• nice cytoplasm

Question 22

Describe a haemorrhagic effusion

Answer 22

turbid -red
SG 1.025-1.040
total protein >30g/L
TNCC 1.5-10*10^9/L (ccompare with peripheral blood)
cells present (WBC from peripheral blood, includes neutrophils), and macrophages

Question 23

Types of haemorrhage and how to distinguish them - 3

Answer 23

IATROGENIC OR ONGOIN (eryhrocytes and platelet clumps)
ACUTE HAEMORRHAGE (erythrophagia)
CHRONIC (siderophages, haematoidin)

Question 24

What might platelets in you fluid mean? 3

Answer 24

• you sampled actual blood
• animal still haemorrhaging (rare)
• iatrogenic haemorrahe

Question 25

Describe a chylous effusion (colour, protein, nucleated cell count, other cells)

Answer 25

opaque, milky SG >1.017 protein variable >30g/L TNCC 1.5-20*10^9/L Cytology: ACUTE - small lymphocytes, macrophages, mature neutrophils, variable CHRONIC: mixed population with increased neutrophils and macrophages but decreased lymphocyte % (although still many)

Question 26

Describe levels of Tg in chylous effusion fluid

Answer 26

Tg in fluid greater than in serum (and cholesterol lower)

Question 27

What is a 'cream top'?

Answer 27

the chylomicrons that form on the top of a chylous effusion if it is refridgerated

Question 28

What can you use to stain lipid droplets?

Answer 28

sudan 3

Question 29

Describe other features of a chylous effusion

Answer 29

-cholesterol:tg ratio of 100mg/dL (1.13mmol/L)

Question 30

What are mesothelial cells? Why are they important?

Answer 30

Normal lining cells of the abdominal and thoracic cavities/ Show 'reactive change' with inflammation or effusions that can cause them to be confused with neoplastic cells. Requires biopsy and histopathology to confirm a diagnosis of a neoplasm.

Question 31

Describe the appearance of mesothelial cells

Answer 31

they have a corona/cytoplasmic bleb that looks a bit like cilia. can have multiple nuclei and other features that make cells look like tumours (although they're not!)

Question 32

Describe some ectopic sources of fluid

Answer 32

Urine --> uroabdomen Bile - bile peritonitis Pancreatitis All of these can produce variable amounts of effusion and inflammation. TNCC and protein levels will vary.

Question 33

Describe uroabdomen fluid - classification

Answer 33

transudate/modified transudate (if chonric)

Question 34

Describe bile peritonitis fluid - classification

Answer 34

green colour, modified transudate/exudate

Question 35

Describe pancreatitis fluid - classification

Answer 35

modified transudate/exudate

Question 36

Describe biochemistry ratios of creatinine, lipase and bilirubin in fluid vs plasma

Answer 36

CREATININE - much higher in urine normally than plasma LIPASE BILIRUBIN (bile duct/gall bladder rupture) - much higher in blood normally. If higher in cavity fluid than in blood, then bilirubin has leaked.

Question 37

Describe equine peritoneal fluid - volume

Answer 37

Normally find low volume in equine abdomen (100-300ml) so can collect 3-5ml from a normal horse. Increased volume = effusion

Question 38

Describe equine peritoneal fluid (colour, protein, nucleated cell count, other cells)

Answer 38

``` pale yellow, clear TNCC 0.5-9.0 * 10^9/L (usually < 4.0*) protein <15g/L specific gravity 1.000 - 1.010 Approximately 50% macrophages and 50% non-degenerate neutrophils ``` roughly equivalent to a modified transudate

Question 39

Describe equine peritoneal fluid - NON-SEPTIC EXUDATE (colour, protein, nucleated cell count, other cells)

Answer 39

amber slightly turbid fluid TNCC >10*10^9/L protein >25g/L neutrophils>macrophages

Question 40

Describe equine peritoneal fluid - SEPTIC EXUDATE (colour, protein, nucleated cell count, other cells)

Answer 40

``` yellow, brown, turbid TNCC > 10*10^9/L protein > 34g/L degenerate neutrophils, bacteria loog for plant material = rupture of perforation of gut wall ```

Question 41

What is enterocentesis?

Answer 41

tap into gut

Question 42

What might you see on enterocentesis?

Answer 42

plant material, protozoa and bacteria (mixed population), very few cells

Question 43

How can you tell apart tapping into the gut or if you have a peracute rupture of the gut with overwhelming inflammation?

Answer 43

with both will see plant material, bacteria and possibly protozoa, cell count will be low if rupture is peracute, clinical impression is important in these cases - horses with gut rupture will quickly develop CV collapse.