Peritoneal Fluid Analysis

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Peritoneal Fluid Analysis

Synonym/acronym: Ascites fluid analysis.

Common use

To evaluate and classify the type of fluid within the peritoneal cavity to assist with diagnosis of cancer, infection, necrosis, and perforation.


Peritoneal fluid (5 mL) collected in a red- or green-top (heparin) tube for amylase, glucose, and alkaline phosphatase; lavender-top (EDTA) tube for cell count; sterile containers for microbiology specimens; 200 to 500 mL of fluid in a clear container with anticoagulant for cytology. Ensure that there is an equal amount of fixative and fluid in the container for cytology.

Normal findings

(Method: Spectrophotometry for glucose, amylase, and alkaline phosphatase; automated or manual cell count, macroscopic examination of cultured organisms, and microscopic examination of specimen for microbiology and cytology; microscopic examination of cultured microorganisms)
Peritoneal FluidReference Value
ColorPale yellow
AmylaseParallels serum values
Alkaline phosphataseParallels serum values
CEAParallels serum values
GlucoseParallels serum values
Red blood cell countNone seen
White blood cell countLess than 300/microL
CultureNo growth
Acid-fast stainNo organisms seen
Gram stainNo organisms seen
CytologyNo abnormal cells seen


The peritoneal cavity and organs within it are lined with a protective membrane. The fluid between the membranes is called serous fluid. Normally only a small amount of fluid is present because the rates of fluid production and absorption are about the same. Many abnormal conditions can result in the buildup of fluid within the peritoneal cavity. Specific tests are usually ordered in addition to a common battery of tests used to distinguish a transudate from an exudate. Transudates are effusions that form as a result of a systemic disorder that disrupts the regulation of fluid balance, such as a suspected perforation. Exudates are caused by conditions involving the tissue of the membrane itself, such as an infection or malignancy. Fluid is withdrawn from the peritoneal cavity by needle aspiration and tested as listed in the previous and following tables.

This procedure is contraindicated for



  • Evaluate ascites of unknown cause
  • Investigate suspected peritoneal rupture, perforation, malignancy, or infection
  • CharacteristicTransudateExudate
    AppearanceClearCloudy or turbid
    Specific gravityLess than 1.015Greater than 1.015
    Total proteinLess than 2.5 g/dLGreater than 3 g/dL
    Fluid-to-serum protein ratioLess than 0.5Greater than 0.5
    LDHParallels serum valueLess than 200 units/L
    Fluid-to-serum LDH ratioLess than 0.6Greater than 0.6
    Fluid cholesterolLess than 55 mg/dLGreater than 55 mg/dL
    White blood cell countLess than 100/microLGreater than 1,000/microL
    LDH = lactate dehydrogenase.

Potential diagnosis

Increased in

    Condition/Test Showing Increased Result

  • Abdominal malignancy (red blood cell [RBC] count, carcinoembryonic antigen, abnormal cytology)
  • Abdominal trauma (RBC count )
  • Ascites caused by cirrhosis (white blood cell [WBC] count, neutrophils greater than 25% but less than 50%)
  • Bacterial peritonitis (WBC count, neutrophils greater than 50%)
  • Peritoneal effusion due to gastric strangulation, perforation, or necrosis (amylase, ammonia, alkaline phosphatase)
  • Peritoneal effusion due to pancreatitis, pancreatic trauma, or pancreatic pseudocyst (amylase)
  • Rupture or perforation of urinary bladder (ammonia, creatinine, urea)
  • Tuberculous effusion (elevated lymphocyte count, positive acid-fast bacillus smear and culture [25% to 50% of cases])

Decreased in

    Condition/Test Showing Decreased Result

    Abdominal malignancy (glucose) Tuberculous effusion (glucose)

Critical findings

  • Positive culture findings in any sterile body fluid.

  • Note and immediately report to the health-care provider (HCP) positive culture results, if ordered, and related symptoms.

  • It is essential that a critical finding be communicated immediately to the requesting health-care provider (HCP). A listing of these findings varies among facilities.

  • Timely notification of a critical finding for lab or diagnostic studies is a role expectation of the professional nurse. Notification processes will vary among facilities. Upon receipt of the critical value the information should be read back to the caller to verify accuracy. Most policies require immediate notification of the primary HCP, Hospitalist, or on-call HCP. Reported information includes the patient’s name, unique identifiers, critical value, name of the person giving the report, and name of the person receiving the report. Documentation of notification should be made in the medical record with the name of the HCP notified, time and date of notification, and any orders received. Any delay in a timely report of a critical finding may require completion of a notification form with review by Risk Management.

Interfering factors

  • Bloody fluids may result from a traumatic tap.
  • Unknown hyperglycemia or hypoglycemia may be misleading in the comparison of fluid and serum glucose levels. Therefore, it is advisable to collect comparative serum samples a few hours before performing paracentesis.

Nursing Implications and Procedure


  • Positively identify the patient using at least two unique identifiers before providing care, treatment, or services.
  • Patient Teaching: Inform the patient this procedure can assist with evaluation of fluid surrounding the abdominal organs.
  • Obtain a history of the patient’s complaints, including a list of known allergens, especially allergies or sensitivities to latex.
  • Obtain a history of the patient’s gastrointestinal and immune system, especially any bleeding disorders and other symptoms, as well as results of previously performed laboratory tests and diagnostic and surgical procedures.
  • Note any recent procedures that can interfere with test results.
  • Record the date of the last menstrual period and determine the possibility of pregnancy in perimenopausal women.
  • Obtain a list of the patient’s current medications, including anticoagulants, aspirin and other salicylates, herbs, nutritional supplements, and nutraceuticals (see Effects of Natural Products on Laboratory Values online at DavisPlus). Such products should be discontinued by medical direction for the appropriate number of days prior to a surgical procedure.
  • Review the procedure with the patient. If patient has ascites, obtain weight and measure abdominal girth. Inform the patient that it may be necessary to remove hair from the site before the procedure. Address concerns about pain and explain that a sedative and/or analgesia will be administered to promote relaxation and reduce discomfort prior to needle insertion through the abdomen wall. Explain that any discomfort with the needle insertion will be minimized with local anesthetics and systemic analgesics. Explain that the anesthetic injection may cause an initial stinging sensation. Explain that after the skin has been anesthetized, a large needle will be inserted through the abdominal wall and a “popping” sensation may be experienced as the needle penetrates the peritoneum. Inform the patient that specimen collection is performed under sterile conditions by an HCP specializing in this procedure and usually takes approximately 30 min to complete.
  • Explain that an IV line will be inserted to allow infusion of IV fluids, antibiotics, anesthetics, and analgesics.
  • Sensitivity to social and cultural issues, as well as concern for modesty, is important in providing psychological support before, during, and after the procedure.
  • Note that there are no food or fluid restrictions unless by medical direction. The requesting HCP may request that anticoagulants and aspirin be withheld. The number of days to withhold medication is dependent on the type of anticoagulant.
  • Make sure a written and informed consent has been signed prior to the procedure and before administering any medications.


  • Potential complications:
  • Bleeding, infection, puncture of surrounding vessels or organs

  • Ensure that anticoagulant therapy has been withheld for the appropriate number of days prior to the procedure. Notify the HCP if patient anticoagulant therapy has not been withheld.
  • Have emergency equipment readily available.
  • Have the patient void, or catheterize the patient to avoid accidental puncture of the bladder if he or she is unable to void.
  • Have the patient remove clothing and change into a gown for the procedure.
  • Avoid the use of equipment containing latex if the patient has a history of allergic reaction to latex.
  • Instruct the patient to cooperate fully and to follow directions. Direct the patient to breathe normally and to avoid unnecessary movement during the local anesthetic and the procedure.
  • Observe standard precautions, and follow the general guidelines in Patient Preparation and Specimen Collection.Positively identify the patient, and label the appropriate specimen container with the corresponding patient demographics, initials of the person collecting the specimen, date and time of collection, and site location.
  • Record baseline vital signs and continue to monitor throughout the procedure. Protocols may vary among facilities.
  • Establish an IV line to allow infusion of IV fluids, anesthetics, analgesics, or IV sedation.
  • Assist the patient to a comfortable seated position with feet and back supported or in high Fowler’s position.
  • Clip hair from the site as needed, cleanse the site with an antiseptic solution, and drape the area with sterile towels prior to the administration of local anesthesia. The skin at the injection site is then anesthetized.
  • The paracentesis needle is inserted 1 to 2 in. below the umbilicus, and fluid is removed. If lavage fluid is required (helpful if malignancy is suspected), saline or Ringer’s lactate can be infused via the needle over a 15- to 20-min period before the lavage fluid is removed. Monitor vital signs every 15 min for signs of hypovolemia or shock.
  • No more than 1,500 to 2,000 mL of fluid should be removed at a time, even in the case of a therapeutic paracentesis, because of the risk of hypovolemia and shock.
  • The needle is withdrawn, and slight pressure is applied to the site. Apply a sterile dressing to the site.
  • Monitor the patient for complications related to the procedure (e.g., allergic reaction, anaphylaxis).
  • Place samples in properly labeled specimen containers, and promptly transport the specimens to the laboratory for processing and analysis.


  • Inform the patient that a report of the results will be made available to the requesting HCP, who will discuss the results with the patient.
  • Instruct the patient to resume usual medications, as directed by the HCP.
  • Monitor vital signs every 15 min for the first hr, every 30 min for the next 2 hr, every hour for the next 4 hr, and every 4 hr for the next 24 hr. Take the patient’s temperature every 4 hr for 24 hr. Monitor intake and output for 24 hr. Notify the HCP if temperature is elevated. Protocols may vary among facilities.
  • Observe/assess the puncture site for bleeding or drainage and signs of inflammation each time vital signs are taken and daily thereafter for several days. Report to the HCP if bleeding is present.
  • Obtain weight and measure abdominal girth if a large amount of fluid was removed.
  • Inform the patient that 1 hr or more of bed rest is required after the procedure.
  • Instruct the patient to immediately report severe abdominal pain. (Note: Rigidity of abdominal muscles indicates developing peritonitis.) Report to HCP if abdominal rigidity or pain is present.
  • Observe/assess for nausea and pain. Administer antiemetic and analgesic medications as needed and as directed by the HCP.
  • Administer antibiotics, as ordered, and instruct the patient in the importance of completing the entire course of antibiotic therapy even if no symptoms are present.
  • Recognize anxiety related to test results, and offer support. Discuss the implications of abnormal test results on the patient’s lifestyle. Provide teaching and information regarding the clinical implications of the test results, as appropriate. Educate the patient regarding access to counseling services, if appropriate.
  • Reinforce information given by the patient’s HCP regarding further testing, treatment, or referral to another HCP. Answer any questions or address any concerns voiced by the patient or family.
  • Depending on the results of this procedure, additional testing may be performed to evaluate or monitor progression of the disease process and determine the need for a change in therapy. Evaluate test results in relation to the patient’s symptoms and other tests performed.

Related Monographs

  • Related tests include cancer antigens, CBC, CBC WBC count and differential, CT abdomen, CT biliary tract and liver, culture and smear mycobacteria, culture blood, culture fungal, culture viral, KUB studies, laparoscopy abdominal, liver and spleen scan, MRI abdomen, US abdomen, and US spleen.
  • Refer to the Gastrointestinal and Immune systems tables at the end of the book for related tests by body system.
Handbook of Laboratory and Diagnostic Tests, © 2013 Farlex and Partners