Difference between revisions of "Colic - Peritoneal Fluid Analysis"

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==Introduction==
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Assessing the pertoneal fluid can give information about the disease process in the very early stages. The fluid sample is collected by [[abdominocentesis]], and it should be used in the work-up of '''severe, recurrent or persistent colic cases'''. The results may indicate whether '''surgery''' is required and potentially provide a '''diagnosis''' and '''prognosis'''.
  
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Assessing the pertioneal fluid can give information about the disease process in the very early stages. Some disease processes such as peritonitis and enteritis produce changes in the peritoneal fluid before the onset of clinical signs. This allows for the early diagnosis of the disease which will favour an improved prognosis for the patient. Strangulating obstructions produce changes in the peritoneal fluid within a few hours of the obstruction occurring. Horses with an intussusception may have normal peritoneal fluid initially as the peritonitis that develops is localised to the portion of entraped bowel.
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Some disease processes such as [[Peritonitis|peritonitis]] and [[Enteritis|enteritis]] produce changes in the peritoneal fluid before the onset of clinical signs. This allows for the '''early diagnosis''' of the disease which will favour an '''improved prognosis''' for the patient. Strangulating obstructions produce changes in the peritoneal fluid within a few hours of the obstruction occurring. Horses with an [[Intussusception - Horse|intussusception]] may have normal peritoneal fluid initially as the peritonitis that develops is localised to the portion of entraped bowel.
  
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Peritoneal fluid should be assessed for colour, turbidity, specific gravity, total nucleated cell count and examined under the microscope for cytology. Normal peritonel fluid is clear to yellow in colour and has a specific gravity of 1.005 mg/dl. The fluid becomes yellow or white and increasingly turbid when there is more protein or cells in it. The initial changes seen in the fluid during gastrointestinal disease are a serosanguinous appearance and an increased red blood cell count and total protein level. The fluid becomes yellow or white and increaingly turbid when there is more protein or cells in it. When the affected portion of bowel becomes ischaemic and necrotic, it leaks cells into the peritoneal fluid. White to yellow, cloudy fluid or exudate will be high in white blood cells. This is seen in septic peritonitis. Red, brown or green fluid can indicate rupture of the gastrointestinal tract and plant material may be present in the sample. A dark red sample may indicate accidental splenic or vessel puncture. The sample will have a higher Packed Cell Volume (CV) than the peripheral blood if it has been obtained from the spleen, and the same PCV as the peripheral blood if it has come from a vessel.  
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==Analysis==
 +
Peritoneal fluid should be assessed for '''colour, turbidity, specific gravity, [[Total protein|total protein]], total nucleated cell count, differential cell count and examined under the microscope for cytology'''. The cytology sample should be stained with Wright's and/or Gram stain and examined for the presence of '''bacteria (intracellular or extracellular), plant material, cellular appearance, a white blood cell count and a differential cell count'''. '''Glucose and lactate levels''' can also be measured.
  
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A high nucleated cell count indicates a ruptured bowel but this is not always the case. Sometimes the nucleated cell count is normal in a case of bowel rupture because the cells may have been lysed in the fluid. 
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===Normal Peritoneal Fluid===
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* Clear to yellow in colour
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* Specific gravity of 1.005 mg/dl
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* Total nucleated cell count of less than 10 (x 10<sup>9</sup>L)
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* Total protein of less than 25g/L
  
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A sample from the fluid should be stained with Wright's and/or Gram stain and examined under the microscope. The sample should be examined for the presence of bacteria (intracellular or extracellular), plant material, cellular appearance, a white blood cell count and a differential cell count.  
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Normal peritoneal fluid is a filtrate of the blood secreted by the peritoneum and it acts to lubricate the abdominal organs, preventing infection and the formation of [[Adhesions|adhesions]]. It is drained by specialist lymphatic lacunae in the diaphragm.
  
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===Abnormal Peritoneal Fluid===
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The peritoneal fluid may be a [[Transudate|transudate]], [[Modified Transudate|modified transudate]] or [[Exudate|exudate]], depending on the level of total protein and the total nucleated cell count. An '''exudate''' is formed in the presence of '''peritoneal [[Inflammation|inflammation]] and [[Ischaemia|ischaemia]] (aka severe [[:Category:Colic in Horses|colic]])''', due to an '''increase in capillary wall permeability'''. Inflammatory cells such as [[Neutrophils|neutrophils]], [[Macrophages|macrophages]] and [[Lymphocytes|lymphocytes]] pass from the capillaries into the peritoneum, producing a fluid with a high total protein and total nucleated cell count. Volume should increase over time, but it may be pocketed within the abdomen so too much significance should not be placed on this. [[Bilirubin#Hyperbilirubinaemia|Hyperbilirubinaemia]] is common in anorexic horses, giving the fluid a very yellow appearance.
 +
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====Visual Inspection====
 +
The initial changes seen in the fluid during gastrointestinal disease show a '''serosanguinous appearance'''. The fluid becomes '''yellow or white and increasingly turbid''' when there is more protein or cells in it. '''Red, brown or green fluid''' can indicate rupture of the gastrointestinal tract and plant material may be present in the sample. In cases of [[Haemorrhage|haemorrhage]] the fluid should not clot, unless it is very acute. If the gut is distended but no ischaemia is present then peritoneal fluid may be completely normal, or have a slightly high volume, total protein and nucleated cell count level. [[Peritonitis]] cases where the bowel is not ischaemic have a large buffy coat when left to settle.
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It is important to remember that a '''blood''' tinged sample may be the result of iatrogenic '''contamination'''. This can be differentiated by spinning the sample down, a pellet of red blood cells will form in iatrogenically contaminated samples - in compromised samples it will not. Equally, if '''plant material''' is present it is important to ensure that the '''bowel''' was not directly sampled. A dark red sample may indicate accidental '''splenic or vessel puncture'''. The sample will have a higher [[PCV|Packed Cell Volume]] (PCV) than the peripheral blood if it has been obtained from the spleen, and the same PCV as the peripheral blood if it has come from a vessel.
 +
 +
====Smell====
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The sample should be smelt. The presence of '''urine, bacteria or gut content''' may be detectable.
 +
 +
====Total Protein and Specific Gravity====
 +
Total protein and spoecific gravity should be analysed using a '''refractometer'''. Levels should be increased where '''peritonitis, severe inflammation and ischaemia''' are present. Levels should be normal in cases of medical colic.
 +
 +
====Total Nucleated Cell Count====
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Total nucleated cell count should correlate fairly closely with the TP and specific gravity, with levels increasing in cases of '''peritonitis, ischaemia and inflammation'''. Levels should remain normal in [[:Category:Medical Colic in the Horse|medical colics]]. 
 +
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====Cytology====
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Cytology is not always performed in the emergency colic work-up. '''Inflammatory cells, red blood cells and [[Mesothelial cells|mesothelial cells]]''' (the cells that line the peritoneum) should be examined and counted. The sample should also be examined for bacteria and plant material.
 +
A high nucleated cell count suggests a ruptured bowel but this is not always the case - sometimes the nucleated cell count is normal because the cells may have been lysed in the fluid. Cases of septic peritonitis will have samples with predominantly toxic and degerate neutrophils. Bacteria may be visible in [[Peritonitis|septic peritonitis]] or rupture of the gut.
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====Bacterial Culture====
 +
Baterial culture should be performed when '''peritonitis''' is suspected. Its use is not appropriate when deciding surgical or medical treatment in emergency colic case, as results are not immediately available.
 +
 +
====Other Tests====
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The fluid can be assessed for '''glucose and lactate''' level. A sample with a glucose concentration higher than that of the peripheral blood indicates septic peritonitis. If the peritoneal lactate concentration is higher than the peripheral blood concentration then intestinal infarction is likely. Serum and peritoneal fluid '''[[creatinine]]''' levels can be measure in cases where '''uroperitoneum''' is suspected (peritoneal creatinine levels should be double than of plasma in these cases).
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==Summary of Peritoneal Fluid Parameters and Intra-abdominal Disorders==
 
{| cellpadding="10" cellspacing="0" border="1"  
 
{| cellpadding="10" cellspacing="0" border="1"  
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|+ Peritoneal Fluid Analysis and Intraabdominal Disorders
 
 
! Clinical Condition
 
! Clinical Condition
 
! Appearance
 
! Appearance
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| Normal
 
| Normal
 
| Clear - Yellow
 
| Clear - Yellow
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| < 2.0
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| < 2.5
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| < 7.5 x10<sup>9</sup>
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| < 10 x10<sup>9</sup>
 
| 20 - 80% mononuclear cells, 40 - 80% neutrophils
 
| 20 - 80% mononuclear cells, 40 - 80% neutrophils
 
|-
 
|-
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| Mostly neutrophils (moderate degeneration), no intracellular bacteria
 
| Mostly neutrophils (moderate degeneration), no intracellular bacteria
 
|}
 
|}
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'''Abdominocentesis and peritoneal fluid analysis are important tools in the colic work-up. They provide information on diagnosis and prognosis, and can help the clinician decide whether or not the colic case will require surgical treatment.'''
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{{Learning
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|flashcards = [[Cytology Q&A 15]]
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}}
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===References===
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Edwards B. (2009) '''Diagnosis and Pathophysiology of Intestinal Obstruction, in Equine Gastroenterology''' courtesy of the ''University of Liverpool'', pp 8 - 9
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Meuller E, Moore J. N, (2008) '''Classification and Pathophysiology of Colic, Gastrointestinal Emergencies and Other Causes of Colic, in Equine Emergencies- Treatments and Procedures''' (3rd Edition) ''Eds Orsini J. A, Divers T.J, Saunders Elsevier''
 +
 +
Milne, E (2004) '''Peritoneal fluid analysis for the differentiation of medical and surgical colic in horses''' ''In Practice 2004 26: 444-44''
 +
 +
Rose R.J, Hodgson D.R (2000) '''Examination of the Alimentary Tract, Alimentary Tract, Manual of Equine Practice''', 2nd Edition, ''Saunders Elsevier'', pp 284 - 286
 +
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RVC staff (2009) '''Alimentary System''' RVC Intergrated BVetMed Course, ''Royal Veterinary College''
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{{review}}
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==Webinars==
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<rss max="10" highlight="none">https://www.thewebinarvet.com/gastroenterology-and-nutrition/webinars/feed</rss>
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[[Category:Colic Diagnosis in the Horse|HZ]]
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[[Category:Expert Review - Horse]]

Latest revision as of 15:04, 4 January 2023


Introduction

Assessing the pertoneal fluid can give information about the disease process in the very early stages. The fluid sample is collected by abdominocentesis, and it should be used in the work-up of severe, recurrent or persistent colic cases. The results may indicate whether surgery is required and potentially provide a diagnosis and prognosis.

Some disease processes such as peritonitis and enteritis produce changes in the peritoneal fluid before the onset of clinical signs. This allows for the early diagnosis of the disease which will favour an improved prognosis for the patient. Strangulating obstructions produce changes in the peritoneal fluid within a few hours of the obstruction occurring. Horses with an intussusception may have normal peritoneal fluid initially as the peritonitis that develops is localised to the portion of entraped bowel.

Analysis

Peritoneal fluid should be assessed for colour, turbidity, specific gravity, total protein, total nucleated cell count, differential cell count and examined under the microscope for cytology. The cytology sample should be stained with Wright's and/or Gram stain and examined for the presence of bacteria (intracellular or extracellular), plant material, cellular appearance, a white blood cell count and a differential cell count. Glucose and lactate levels can also be measured.

Normal Peritoneal Fluid

  • Clear to yellow in colour
  • Specific gravity of 1.005 mg/dl
  • Total nucleated cell count of less than 10 (x 109L)
  • Total protein of less than 25g/L

Normal peritoneal fluid is a filtrate of the blood secreted by the peritoneum and it acts to lubricate the abdominal organs, preventing infection and the formation of adhesions. It is drained by specialist lymphatic lacunae in the diaphragm.

Abnormal Peritoneal Fluid

The peritoneal fluid may be a transudate, modified transudate or exudate, depending on the level of total protein and the total nucleated cell count. An exudate is formed in the presence of peritoneal inflammation and ischaemia (aka severe colic), due to an increase in capillary wall permeability. Inflammatory cells such as neutrophils, macrophages and lymphocytes pass from the capillaries into the peritoneum, producing a fluid with a high total protein and total nucleated cell count. Volume should increase over time, but it may be pocketed within the abdomen so too much significance should not be placed on this. Hyperbilirubinaemia is common in anorexic horses, giving the fluid a very yellow appearance.

Visual Inspection

The initial changes seen in the fluid during gastrointestinal disease show a serosanguinous appearance. The fluid becomes yellow or white and increasingly turbid when there is more protein or cells in it. Red, brown or green fluid can indicate rupture of the gastrointestinal tract and plant material may be present in the sample. In cases of haemorrhage the fluid should not clot, unless it is very acute. If the gut is distended but no ischaemia is present then peritoneal fluid may be completely normal, or have a slightly high volume, total protein and nucleated cell count level. Peritonitis cases where the bowel is not ischaemic have a large buffy coat when left to settle.

It is important to remember that a blood tinged sample may be the result of iatrogenic contamination. This can be differentiated by spinning the sample down, a pellet of red blood cells will form in iatrogenically contaminated samples - in compromised samples it will not. Equally, if plant material is present it is important to ensure that the bowel was not directly sampled. A dark red sample may indicate accidental splenic or vessel puncture. The sample will have a higher Packed Cell Volume (PCV) than the peripheral blood if it has been obtained from the spleen, and the same PCV as the peripheral blood if it has come from a vessel.

Smell

The sample should be smelt. The presence of urine, bacteria or gut content may be detectable.

Total Protein and Specific Gravity

Total protein and spoecific gravity should be analysed using a refractometer. Levels should be increased where peritonitis, severe inflammation and ischaemia are present. Levels should be normal in cases of medical colic.

Total Nucleated Cell Count

Total nucleated cell count should correlate fairly closely with the TP and specific gravity, with levels increasing in cases of peritonitis, ischaemia and inflammation. Levels should remain normal in medical colics.

Cytology

Cytology is not always performed in the emergency colic work-up. Inflammatory cells, red blood cells and mesothelial cells (the cells that line the peritoneum) should be examined and counted. The sample should also be examined for bacteria and plant material. A high nucleated cell count suggests a ruptured bowel but this is not always the case - sometimes the nucleated cell count is normal because the cells may have been lysed in the fluid. Cases of septic peritonitis will have samples with predominantly toxic and degerate neutrophils. Bacteria may be visible in septic peritonitis or rupture of the gut.

Bacterial Culture

Baterial culture should be performed when peritonitis is suspected. Its use is not appropriate when deciding surgical or medical treatment in emergency colic case, as results are not immediately available.

Other Tests

The fluid can be assessed for glucose and lactate level. A sample with a glucose concentration higher than that of the peripheral blood indicates septic peritonitis. If the peritoneal lactate concentration is higher than the peripheral blood concentration then intestinal infarction is likely. Serum and peritoneal fluid creatinine levels can be measure in cases where uroperitoneum is suspected (peritoneal creatinine levels should be double than of plasma in these cases).

Summary of Peritoneal Fluid Parameters and Intra-abdominal Disorders

Clinical Condition Appearance Total Protein (g/dl) Total Nucleated Cells/L Cytology
Normal Clear - Yellow < 2.5 < 10 x109 20 - 80% mononuclear cells, 40 - 80% neutrophils
Non-strangulating Obstruction Clear - Yellow, Slightly turbid < 3.0 < 3.0 - 15.0 x 109 Mostly neutrophils (preserved)
Strangulating Obstruction Red - Brown, Turbid 2.5 - 6.0 5.0 - 50.0 x 109 Mostly neutrophils (degenerate)
Proximal Enteritis Yellow - Red, Turbid 3.0 - 4.5 < 10.0 x 109 Mostly neutrophils (preserved)
Bowel Rupture Red - Brown - Green, Turbid with or without particulate matter 5.0 - 6.5 20 - 150 x 109 > 95% neutrophils ( severely degenerate), intracellular or extracellular bacteria, with or without particulate matter
Septic Peritonitis Yellow - White, Turbid > 3.0 20.0 - 100.0 x 109 Mostly neutrophils (degenerate)
Accidental Enterocentesis Brown - Green, with or without paticulate matter Variable < 1.0 x 109 Free bacteria, plant material, few cells
Intraabdominal haemorrhage Dark red Similar TPP to peripheral blood White Blood Cell Count increases with time PCV less than peripheral blood, erythrocytophagia, few if any platelets
Post-celiotomy Yellow - Red, Turbid Variable Variable Mostly neutrophils (moderate degeneration), no intracellular bacteria


Abdominocentesis and peritoneal fluid analysis are important tools in the colic work-up. They provide information on diagnosis and prognosis, and can help the clinician decide whether or not the colic case will require surgical treatment.


Colic - Peritoneal Fluid Analysis Learning Resources
FlashcardsFlashcards logo.png
Flashcards
Test your knowledge using flashcard type questions 		Cytology Q&A 15


References

Edwards B. (2009) Diagnosis and Pathophysiology of Intestinal Obstruction, in Equine Gastroenterology courtesy of the University of Liverpool, pp 8 - 9

Meuller E, Moore J. N, (2008) Classification and Pathophysiology of Colic, Gastrointestinal Emergencies and Other Causes of Colic, in Equine Emergencies- Treatments and Procedures (3rd Edition) Eds Orsini J. A, Divers T.J, Saunders Elsevier

Milne, E (2004) Peritoneal fluid analysis for the differentiation of medical and surgical colic in horses In Practice 2004 26: 444-44

Rose R.J, Hodgson D.R (2000) Examination of the Alimentary Tract, Alimentary Tract, Manual of Equine Practice, 2nd Edition, Saunders Elsevier, pp 284 - 286

RVC staff (2009) Alimentary System RVC Intergrated BVetMed Course, Royal Veterinary College


This article has been peer reviewed but is awaiting expert review. If you would like to help with this, please see more information about expert reviewing.


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