Peritoneal Fluid – Ascitic Fluid

An excess of fluid collects in the peritoneal cavity for a variety of reasons, including heart failure, liver failure, infection and malignancy. The clinician will aspirate the fluid from the abdominal cavity. Most peritoneal fluid specimens are submitted to the laboratory for cytologic examination to rule out malignancy.

Peritoneal fluid often contains increased amounts of protein that will cause the fluid to clot spontaneously within minutes after removal from the patient. Clotting interferes with optimal cytologic examination and has to be inhibited with an anti-coagulant.

Specimen Collection for Culture

  1. Collect the specimen in a sterile container.
  2. Only a relatively small aliquot of the specimen (10-20 cc) needs to be sent to the laboratory.
  3. Do not add any fixative.
  4. Keep the specimen at room temperature.

Specimen Collection for Cytologic Examination

  1. The entire specimen, or an aliquot of at least 100 cc, should be sent to the laboratory.
  2. Collect the specimen in a screw-top container. Fasten the lid securely to avoid spillage.
  3. Heparin must be added to the specimen to prevent clotting (10 units of heparin for every 1 cc of fluid). It is best to add the heparin to the container before collecting the specimen. Estimate the quantity of heparin that should be added. Err on the side of adding an excess of heparin because excess heparin will not compromise the specimen. Swirl the specimen as it is collected to ensure even distribution of the heparin in the specimen.
  4. Do not add any fixative to the specimen.
  5. Keep specimen at room temperature.
  6. Complete the Calpath cytology requisition form per the instructions.

After collecting the specimen, please do the following:

  • Place the specimen in the Calpath specimen bag (if it will fit into the bag).
  • Place the requisition form in the side slot of the Calpath specimen bag.
  • Call Calpath for a pickup or place the Calpath specimen bag in the location where our courier usually picks up your daily specimens.