PERITONEAL FLUID EXAMINATION

---

Specimen: Ascitic, peritoneal fluid in separate, sterile containers for microbiology, chemical pathology and cytology; for cytology, as much fluid as possible should be collected; heparin (at a final concentration of 5U/mL of fluid) should be added as an anticoagulant.

Method: Macroscopic examination; microscopic examination - wet film, Gram stain; bacterial culture; measurement of glucose, protein, amylase, if appropriate; cytology. Additional tests if appropriate: stains and culture (large volume) for Mycobacterium tuberculosis; LD, LD isoenzymes.

Application: Investigation of ascites, peritoneal fluid collections.

Interpretation: An increase in neutrophils (>250 x 10³/L) is associated with peritonitis (bacterial, tuberculous, pancreatic or malignant). Protein levels >25 g/L (exudate) favour inflammatory or malignant ascites. Amylase activity is increased in pancreatitis. Occasionally LD isoenzymes may help to determine the cause of an exudate: LD5 is derived from neutrophils; LD2 and LD3 suggest malignancy; LD1 and LD2 are derived from red cells. Cytology may detect primary or metastatic malignancy.

Reference: Levison ME and Bush LM. In: Mandell GL et al eds. Principles and Practice of Infectious Diseases. 4th ed. Churchill Livingstone 1995. Koss LG ed. Diagnostic Cytology and its Histopathologic Basis. 4th ed. Lippincott 1992.

---