What laboratory tests should be sent with paracentesis (percutaneous abdominal fluid aspiration)?

From the Guidelines

When performing a paracentesis, the following labs should be sent: cell count with differential, albumin, and total protein, as these are essential for diagnosing spontaneous bacterial peritonitis (SBP) and calculating the serum-ascites albumin gradient (SAAG) 1.

Key Labs to Send

• Cell count with differential to identify SBP if the neutrophil count exceeds 250 cells/mm³ 1
• Albumin to calculate the SAAG, which distinguishes between portal hypertension (SAAG ≥1.1 g/dL) and other causes like malignancy or infection (SAAG <1.1 g/dL) 1
• Total protein to help differentiate between various causes of ascites

Additional Tests

• In cases of suspected infection, ascitic fluid culture with bedside inoculation of blood culture bottles should be performed to guide the choice of antibiotic treatment 1
• For suspected malignancy, cytology should be included, as the sensitivity of cytology in detecting peritoneal carcinomatosis is high if multiple samples are sent and processed promptly 1

Best Practice

• Always inoculate blood culture bottles at the bedside with ascitic fluid to improve bacterial detection rates 1
• A diagnostic paracentesis should be performed without delay to rule out SBP in all cirrhotic patients with ascites on hospital admission, and in patients with GI bleeding, shock, fever, or other signs of systemic inflammation 1

From the Research

Paracentesis Labs to Send

To determine the necessary labs to send for paracentesis, the following points should be considered:

• The ascitic fluid analysis for spontaneous bacterial peritonitis or portal hypertension should include:
  • Ascitic fluid white blood cell and polymorphonuclear leukocyte (PMN) count 2
  • Ascitic fluid pH 2
  • Blood-ascitic fluid pH gradient 2
  • Serum-ascites albumin gradient 2
• Immediate inoculation of culture bottles improves diagnostic yield vs delayed inoculation 2
• The diagnostic accuracy of ascitic fluid analysis is increased with the following parameters:
  • PMN count >250 cells/microL 2
  • Ascitic fluid leukocyte count >1000 cells/microL 2
  • pH < 7.35 2
  • Blood-ascitic fluid pH gradient > or = 0.10 2
• Early paracentesis is essential for rapid diagnosis and optimal treatment of spontaneous bacterial peritonitis, and delayed paracentesis is associated with increased in-hospital mortality 3