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An exudate is a fluid emitted by an organism through pores or a wound, a process known as exuding or exudation.[1] Exudate is derived from exude 'to ooze'

Latin exsūdāre 'to (ooze out) sweat' (ex- 'out' and sūdāre 'to sweat').[3]


An exudate is any fluid that filters from the circulatory system into lesions or areas of inflammation. It can be a pus-like or clear fluid. When an injury occurs, leaving skin exposed, it leaks out of the blood vessels and into nearby tissues. The fluid is composed of serum, fibrin, and leukocytes. Exudate may ooze from cuts or from areas of infection or inflammation.[4]


Transudate vs. exudate
Transudate Exudate
Main causes
osmotic pressure
vascular permeability
Appearance Clear[5] Cloudy[5]
Specific gravity
Protein content
2.5 g/dL
> 2.9 g/dL[6]
fluid protein/
serum protein
< 0.5 > 0.5[7]
Serum [albumin] - Effusion [albumin]
> 1.2 g/dL < 1.2 g/dL[8]
fluid LDH
upper limit for serum
< 0.6 or < 23 > 0.6[6] or > 23[7]
Cholesterol content < 45 mg/dL > 45
Radiodensity on CT scan 2 to 15 HU[9] 4 to 33 HU[9]

Types of exudates: Serous, Serosanguineous, Sanguineous, Hemorrhaging and Purulent drainage.

  • Serous: Clear straw colored liquid that drains from the wound. This is a normal part of the healing process.
  • Serosanguineous: Small amount of blood is present in the drainage; it is pink in color due to the presence of red blood cells mixed with serous drainage. This is a normal part of the healing process.
  • Sanguineous: This type of drainage contains red blood due to trauma of blood vessels, this may occur while cleaning the wound. Sanguineous drainage is abnormal.
  • Hemorrhaging: This type of drainage contains frank blood from a leaking blood vessel. This will require emergency treatment to control the bleed. This type of drainage is abnormal.
  • Purulent drainage: This type of drainage is malodorous and can be yellow, gray, or greenish in color. This is an indication of an infection.

Exudates vs. transudates

There is an important distinction between

specific gravity of extracted fluid. Specific gravity is used to measure the protein content of the fluid. The higher the specific gravity, the greater the likelihood of capillary permeability changes in relation to body cavities. For example, the specific gravity of the transudate is usually less than 1.012 and a protein content of less than 2 g/100 mL (2 g%). Rivalta test
may be used to differentiate an exudate from a transudate. It is not clear if there is a distinction in the difference of transudates and exudates in plants.

Plant exudates

Plant exudates include

microorganisms of the rhizosphere.[15][16]

See also


  1. ^ "exudate". The Free Dictionary - Medical. Retrieved 5 August 2014.
  2. Merriam Webster
    . 2008. Retrieved 2008-07-04.
  3. .
  4. ^ "Exudate". MedlinePlus.
  5. ^ a b The University of Utah • Spencer S. Eccles Health Sciences Library > WebPath images > "Inflammation".
  6. ^
    PMID 9106577
  7. ^ .
  8. .
  9. ^ .
  10. ^ Robbins Basic Pathology 7th ed
  11. ^ About.com > Malignant Pleural Effusion By Lynne Eldridge MD. Updated March 27, 2010
  12. . Retrieved 2 October 2012.
  13. .
  14. .
  15. .
  16. .

External links