What Is a Peritoneal Fluid Culture?

    The peritoneal space is the area between the abdominal wall and the organs it houses. This space is typically empty, or has a small amount of fluid, but a buildup of fluid can occur if you have a disease or infection.

    Inflammation of the lining of the abdominal wall, or the peritoneum, can also occur. This causes pain, nausea and vomiting, and constipation. If left untreated, it can be life-threatening. It can be caused by a variety of diseases, which your doctor can then diagnose and treat.

    A peritoneal fluid culture is a test that is performed on a small sample of peritoneal fluid. It may also be called an abdominal tap or paracentesis. The laboratory examines the fluid for any bacteria or fungi that may be causing an infection.

    Why Is a Peritoneal Fluid Culture Necessary?

    When the peritoneum is inflamed, it is typically because bacteria or fungi have entered the peritoneal space. The blood and lymph nodes can cause an infection in the peritoneum, causing primary peritonitis. (“Peritonitis” means that the peritoneum is inflamed.) More commonly, infection spreads to the space from from the biliary or gastrointestinal tract. This is called secondary peritonitis.

    Illnesses that increase the risk of developing peritonitis include:

    • liver disease
    • ulcerative colitis
    • stomach ulcers
    • pelvic inflammatory disease
    • a weakened immune system

    Peritonitis can be dangerous, causing sepsis and lung infections. Sepsis is an infection in the body caused by the body reacting to bacteria that are present. If there is a large amount of fluid in the peritoneum, it can cause abdominal pain. Large amounts of fluid may be removed to ease discomfort.

    In order to treat peritonitis, the underlying cause needs to be determined. A peritoneal fluid culture can help make a diagnosis.

    How Do I Prepare for this Test?

    You do not have to do anything special for this procedure, other than follow your doctor’s instructions. If necessary, the area will be shaved prior to the insertion of the needle.

    Tell your doctor if you:

    • are allergic to any numbing medication or other drugs
    • have a bleeding disorder
    • are taking any medications or supplements, including herbal medications and over-the-counter drugs
    • are pregnant or think you might be pregnant

    How Is a Peritoneal Fluid Culture Performed?

    A peritoneal fluid culture can be performed in your doctor’s office or a hospital. You will be asked to empty your bladder before the procedure. A spot on your lower abdomen will be cleaned with an antiseptic, and you will receive local anesthesia to numb the area.

    A needle will be inserted 1 to 2 inches into your abdominal cavity. (A small incision may be necessary if there is difficulty inserting the needle.) Fluid is removed through a syringe.

    During the procedure, you might feel pressure. If a lot of fluid is being removed, dizziness or lightheadedness is not uncommon. If you feel discomfort or dizziness, tell your doctor.

    Are There Any Risks to the Procedure?

    You will be asked to sign a consent form before the procedure. There is a small chance of puncturing the bowel, bladder, or an abdominal blood vessel. If you are having a large amount of fluid removed, you will have a slight risk of low blood pressure or kidney failure. As with all invasive procedures, there is also a risk of infection.

    Talk with your doctor about your concerns prior to your appointment.

    Interpreting Your Test Results

    Once the culture is done, it is sent to a laboratory, where a Gram stain and culture are performed. A Gram stain is used to show the differences in the types of bacteria. Abnormal results might show:

    • liver cirrhosis
    • heart disease
    • pancreatic disease
    • a damaged bowel
    • an infection

    Once your doctor gets the results, he or she can start treatment of the underlying condition. In some cases, additional follow-up tests may be needed