Peritoneal Fluid Analysis

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.At a Glance
Why Get Tested?
To help diagnose the cause of peritonitis, an inflammation of the membrane lining the abdomen, and/or peritoneal fluid accumulation, where fluid builds up in the abdomen or around internal organs (called ascites)
When To Get Tested?
When you have abdominal pain and swelling, nausea, and/or fever and your health care practitioner suspects you have peritonitis or ascites
Sample Required?
A peritoneal fluid sample obtained by inserting a needle into the abdominal cavity
Test Preparation Needed?
You will be asked to empty your bladder prior to sample collection.
What is being tested?
Peritoneal fluid is a liquid that acts as a lubricant in the abdominal cavity. It is found in small quantities (generally 5-20 mL) between the layers of the peritoneum that line the abdominal wall. Peritoneal fluid acts to moisten the outside of the organs and to reduce the friction of organ movement during digestion and movement.
A variety of conditions and diseases can cause inflammation of the peritoneum (peritonitis) and/or excessive accumulation of peritoneal fluid (peritoneal effusion or ascites). Peritoneal fluid analysis is a group of tests that evaluate this liquid to determine the cause of the increased fluid.
The two main reasons that fluid may collect in the abdominal cavity are:
- An imbalance between the pressure within blood vessels—which drives fluid out of blood vessels—and the amount of protein in blood—which keeps fluid in blood vessels. The fluid that accumulates in this case is called a transudate. Transudates are most often caused by congestive heart failure, nephrotic syndrome, or hepatic cirrhosis.
- An injury or inflammation of the peritoneum, in which case the fluid is called an exudate. This type of fluid may be the result of conditions such as infection, malignancies (metastatic cancer, lymphoma, mesothelioma), pancreatitis, ruptured gallbladder, or autoimmune disease.
Determining the type of fluid present (transudate or exudates) is important because it helps narrow down the possible causes of fluid buildup or inflammation. Healthcare practitioners and laboratorians use an initial set of tests, including cell count, serum and fluid albumin levels, and appearance of the fluid, to distinguish between transudates and exudates. Once the fluid is determined to be one or the other, additional tests may be performed to further pinpoint the disease or condition causing ascites.
Common Questions
Related Content
On This Site
Tests: Pleural Fluid Analysis, Pericardial Fluid Analysis, Gram Stain, Susceptibility Testing, Glucose Tests, Albumin, White Blood Cell Count, Red Blood Cell Count, AFB Testing, Lactate Dehydrogenase (LD), Adenosine Deaminase
Elsewhere On The Web
MedlinePlus Medical Encyclopedia: Peritonitis – spontaneous bacterial
MedlinePlus Medical Encyclopedia: Ascites
American Cancer Society: Malignant Mesothelioma Detailed Guide
National Cancer Institute: Malignant Mesothelioma
View Sources
Sources Used in Current Review
Wolf, D. (Updated 2014 December 10). Chylous ascites. Medscape Reference. Available online at http://emedicine.medscape.com/article/185777-overview#showall. Accessed 9/9/2016.
Christensen, B. (Updated 2014 December 15). Serum ascites albumin gradient (SAAG) interpretation. Medscape Reference. Available online at http://www.mayoclinic.org/diseases-conditions/peritonitis/basics/definition/con-20032165. Accessed 9/9/2016.
Lal, S. K. (Updated 2015 February 11). Peritoneal fluid analysis. MedlinePlus Medical Encyclopedia. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003626.htm. Accessed 9/9/2016.
Mayo Clinic Staff. (Updated 2015 March 23). Peritonitis. Mayo Clinic. Available online at http://www.mayoclinic.org/diseases-conditions/peritonitis/basics/definition/con-20032165. Accessed 9/9/2016.
Lal, S. K. (2015 August 14). Ascites. MedlinePlus Medical Encyclopedia. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/000286.htm. Accessed 9/9/2016.
Shlamovitz, G. L. (Updated 2016 July 28). Paracentesis. Medscape Reference. Available online at http://emedicine.medscape.com/article/80944-overview. Accessed 9/9/2016.
Bhutta RA, Syed NA, Ahmad A. Peritoneal fluid analysis (Ascitic fluid analysis, Peritoneal tap or abdominal paracentesis, or abdominal tap) part 3. Available online at http://www.labpedia.net/test/227. Accessed Sept 2016.
Shah, Rahil. Ascites. Medscape. Available online at http://emedicine.medscape.com/article/170907-overview#a5. Accessed Sept 2016.
Sources Used in Previous Reviews
Pagana, Kathleen D. & Pagana, Timothy J. (© 2007). Mosby’s Diagnostic and Laboratory Test Reference 8th Edition: Mosby, Inc., Saint Louis, MO. Pp 694-699.
Wu, A. (2006). Tietz Clinical Guide to Laboratory Tests, Fourth Edition. Saunders Elsevier, St. Louis, Missouri. Pp 1535-1536.
Thomas, Clayton L., Editor (1997). Taber’s Cyclopedic Medical Dictionary. F.A. Davis Company, Philadelphia, PA [18th Edition]. Pp 1448-1449.
Forbes, B. et. al. (© 2007). Bailey & Scott’s Diagnostic Microbiology, Twelfth Edition: Mosby Elsevier Press, St. Louis, Missouri. Pp 904 – 913.
Van Voorhees, B. (2007 January 22, Updated). Peritoneal fluid analysis. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003626.htm. Accessed on 6/21/08.
Lehrer, J. (2006 November 14, Updated). Peritonitis – spontaneous. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/000648.htm. Accessed on 6/21/08.
(2002 May 13). National Cancer Institute. Mesothelioma: Questions and Answers [On-line information]. Available online at http://www.cancer.gov/cancertopics/factsheet/sites-types/mesothelioma. Accessed on 7/3/08.
(2008 March 22, Updated). ACS. Malignant Mesothelioma Detailed Guide [On-line information]. Available online at http://www.cancer.org/docroot/CRI/content/CRI_2_4_7x_CRC_Malignant_Mesothelioma_PDF.asp. Accessed on 7/3/08.
Carl Kjeldsberg and Joseph Knight. Body Fluids. Third edition. ASCP Press. Pp. 223-253.
Shlamovitz, G. and Shah, N. (Updated 2012 May 9). Paracentesis. Medscape Reference. [On-line information]. Available online at http://emedicine.medscape.com/article/80944-overview. Accessed June 2012.
Dugdale, D. (Updated 2011 February 4). Peritoneal fluid analysis. MedlinePlus Medical Encyclopedia. [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003626.htm. Accessed June 2012.
Daley, B. et. al. (Updated 2011 March 29). Peritonitis and Abdominal Sepsis. Medscape Reference [On-line information]. Available online at http://emedicine.medscape.com/article/180234-overview. Accessed June 2012.
Zieve, D. (2011 October 16). Ascites. MedlinePlus Medical Encyclopedia . [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/000286.htm. Accessed June 2012.
Wolf, D. and Raghuraman, U. (Updated 2011 March 21). Chylous Ascites. Medscape Reference. [On-line information]. Available online at http://emedicine.medscape.com/article/185777-overview#showall through http://emedicine.medscape.com. Accessed June 2012.
Herrine, S. (Revised 2009 July). Ascites. Merck Manual for Healthcare Professionals. [On-line information]. Available online through http://www.merckmanuals.com. Accessed June 2012.
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