At a glance
Also known as
Ascitic fluid analysis
Why get tested?
To help diagnose the cause of peritonitis and/or peritoneal fluid accumulation (called )
When to get tested?
When a doctor suspects that someone with abdominal pain and swelling, nausea, and/or fever has a condition associated with of the (peritonitis) or ascites.
A peritoneal fluid sample obtained by inserting a needle into the abdominal cavity
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 . 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 of the liver (80% in Western Europe and North America).
Among the other causes are congestive heart failure, cancer, lymphoma, ), 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 (see Common questions).
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.
What is paracentesis and how is it performed?
Paracentesis is the removal of peritoneal fluid from the abdominal cavity with a needle, tubing, and a container that may have a vacuum. The patient is positioned lying down with the head of the bed raised. A local anaesthetic is applied and then the doctor inserts the needle into the abdominal cavity and the fluid is removed.
Are there other reasons to do a paracentesis?
Yes. Sometimes it will be performed to drain excess peritoneal fluid - to relieve pressure in the abdomen. The volume of fluid removed may be large - sometimes as much as four litres or more. This may need to be repeated periodically with some diseases.