Peritoneal Fluid Analysis

In paracentesis, a needle is used to withdraw (aspirate) fluid from the peritoneal cavity, which surrounds the organs of the abdomen. The fluid sample is sent to a laboratory for analysis to identify the cause of ascites (excess fluid in the abdomen). This procedure may also be performed as a therapeutic measure to remove this excess peritoneal fluid.

Purpose of the Paracentesis

  • To detect the perforated viscus in a patient with an acute abdomen or someone who experienced trauma to the abdomen
  • To find out why there is fluid build-up in the abdomen that causes bleeding, infections and diseases of organs
  • To determine the cause of ascites and help select an appropriate treatment
  • To relieve excessive pressure on the organs in the abdomen, which causes discomfort and interferes with the ability to eat and digest properly

Who Performs Paracentesis

  • A physician

Special Concerns about Paracentesis

  • Paracentesis should not be performed in people with untreated bleeding disorders or in those who have had prior extensive abdominal surgery.

Before the Paracentesis

  • Tell your doctor if you are taking any antimicrobial drugs, such as antibiotics.
  • Your weight and abdominal girth may be measured.
  • You will be instructed to empty your bladder before the procedure begins.

What You Experience

  • You are asked to remove your shirt and lie down on a table or bed, or to sit in a chair with your feet placed flat on the floor or supported by a stool. You must remain still during the procedure.
  • The skin at the site of injection (usually about 1 to 2 inches below the navel) is shaved and cleansed with an antiseptic solution. A local anesthetic is injected to numb the area.
  • If a small amount of fluid is being withdrawn, an aspiration needle is inserted through the abdominal wall and into the peritoneal cavity. If larger amounts must be drained, a small incision is made and a larger needle and thin tube (cannula) are used instead.
  • CT scanning or ultrasound imaging may be used to guide the placement of the needle.
  • You will feel pressure and slight pain as the needle is inserted and will hear an audible sound as it penetrates the tough membrane that lines the abdominal cavity (peritoneum).
  • Fluid is withdrawn through the needle and placed into multiple specimen containers.
  • The procedure takes 10 to 15 minutes.

Risks and Complications of Paracentesis

  • Overall, the test is very safe. However, this is a risk (very small) of it resulting in infection, excessive bleeding or a punctured loop of the bowel.
  • There may be some stinging or burning while the anesthesia is injected. Once the area is numb, you will not feel pain.
  • Potentially dangerous complications of this procedure include unintentional injury of internal organs or blood vessels with the needle, bleeding, edema (swelling), infection, and hypotension (low blood pressure). Emergency equipment is readily available if such complications arise.
  • The risk of complications is reduced if CT scanning or ultrasound is used to guide needle insertion.

After the Paracentesis

  • The needle is withdrawn and pressure is placed on the puncture site with sterile gauze pads for 3 to 5 minutes. A bandage is then applied.
  • Your blood pressure and vital signs will be monitored periodically, and the puncture site will be observed for signs of bleeding or inflammation, usually for a few hours.
  • Your weight and abdominal girth may be measured again and compared to your pretest values.
  • If no complications develop and you have no health problems that require hospitalization, you are free to leave the testing facility.

Paracentesis Results

  • The specimen containers may be sent to several different laboratories for examination. The fluid may be analyzed for the presence of white blood cells, bacteria, protein, amylase (a type of enzyme secreted by the pancreas), and other components.
  • Your doctor will diagnose the cause of the peritoneal effusion based on results from these laboratory tests. Possible causes include congestive heart failure, tuberculosis, cancer, cirrhosis and other liver diseases, pancreatitis (inflammation of the pancreas), infection, and various fungal or parasitic diseases.
  • Appropriate treatment will be initiated, depending on the specific problem.


The Johns Hopkins Consumer Guide to Medical Tests

Simeon Margolis, M.D., Ph.D., Medical Editor

Updated by Remedy Health Media

Publication Review By: the Editorial Staff at

Published: 10 Jan 2012

Last Modified: 10 Jan 2012