Peritoneal fluid analysis

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Also known as: Ascitic fluid analysis
Formal name: Peritoneal fluid analysis

At a Glance

Why Get Tested?

To help diagnose the cause of peritonitis and/or peritoneal fluid accumulation (called ascites)

When to Get Tested?

When a doctor suspects that someone with abdominal pain and swelling, nausea, and/or fever has a condition associated with inflammation of the peritoneum (peritonitis) or ascites.

Sample Required?

A peritoneal fluid sample obtained by inserting a needle into the abdominal cavity

The Test Sample

What is being tested?

Peritoneal fluid is a liquid that acts as a lubricant in the abdominal cavity. It is found in small quantities between the layers of the peritoneum. Peritoneal fluid is produced by mesothelial cells in the membranes and acts to moisten the outside of the organs and to reduce the friction of organ movement during digestion.

A variety of conditions can cause accumulation of peritoneal fluid (ascites). The most common cause by far is cirrhosis of the liver (80% in Western Europe and north America).

Among the other causes are congestive heart failure, metastatic cancer, lymphoma, mesothelioma), rheumatoid disease, or systemic lupus erythematosus.

Laboratories use an initial set of tests (cell count, albumin and appearance of the fluid) in addition to the history and physical examination of the patient to help determine the cause of the accumulation of fluid.

How is the sample collected for testing?

A sample of peritoneal fluid is collected by a doctor with a syringe and needle using a procedure called paracentesis.
A sample of blood may be collected at the same time for measurement of serum albumin.

Is any test preparation needed to ensure the quality of the sample?

You will be asked to empty your bladder prior to sample collection.

The Test

Common Questions

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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.