What fluid studies should be obtained for paracentesis?

From the Guidelines

For paracentesis, the essential fluid studies that should be obtained include cell count with differential, albumin level, total protein, culture and Gram stain, and glucose, as recommended by the most recent guidelines 1. The cell count helps identify spontaneous bacterial peritonitis (SBP) if the neutrophil count exceeds 250 cells/mm³. The serum-ascites albumin gradient (SAAG) differentiates between portal hypertension (SAAG ≥1.1 g/dL) and other causes of ascites. Cultures are crucial for identifying infectious organisms, while protein levels help assess the risk of SBP. Glucose levels may be decreased in SBP or malignancy. Additional tests that should be considered based on clinical suspicion include lactate dehydrogenase (LDH), amylase, triglycerides, cytology, and acid-fast bacilli smear and culture. These tests collectively provide comprehensive information about the etiology of ascites and guide appropriate management, prioritizing morbidity, mortality, and quality of life as outcomes, as supported by recent studies 1.

Some key points to consider:

• A diagnostic paracentesis should be performed in all patients with new onset grade 2 or 3 ascites, and in all patients hospitalized for worsening of ascites or any complication of cirrhosis 1.
• The initial laboratory investigation of ascites fluid should include an ascitic fluid cell count and differential, ascitic fluid total protein, and albumin to calculate the SAAG 1.
• If ascitic fluid infection is suspected, bacterial culture of the fluid in aerobic and anaerobic blood culture bottles inoculated at the bedside should be performed 1.
• Patients presenting with gastrointestinal bleeding and underlying ascites due to cirrhosis should receive prophylactic antibiotic treatment to prevent the development of SBP 1.

Overall, the choice of fluid studies for paracentesis should be guided by the clinical presentation and suspicion of underlying causes, with a focus on identifying SBP, portal hypertension, and other complications of cirrhosis, as recommended by the most recent and highest quality studies 1.

From the Research

Fluid Studies for Paracentesis

To determine the necessary fluid studies for paracentesis, it is essential to consider the clinical context and the potential complications associated with the procedure.

• The analysis of ascitic fluid is crucial in diagnosing spontaneous bacterial peritonitis (SBP), a common complication in patients with liver cirrhosis 2.
• The final diagnosis of SBP requires the analysis of ascites and the presence of > 250 mm3 neutrophil polymorphonuclear (PMN) in ascites 2.
• Early paracentesis is essential for rapid diagnosis and optimal treatment of SBP, and delayed paracentesis is associated with increased in-hospital mortality 3.
• The treatment of SBP involves the use of non-nephrotoxic broad-spectrum antibiotics expected to cover the typical bacterial flora associated with SBP, and the antibiotic regimen is adjusted based on the results of ascitic fluid cultures 4.
• Routine analysis of ascitic fluid at the time of therapeutic paracentesis in asymptomatic outpatients may not be necessary, as the prevalence of spontaneous bacterial peritonitis and culture-negative neutrocytic ascites in this population is near 0% 5.

Recommended Fluid Studies

Based on the available evidence, the following fluid studies should be obtained for paracentesis:

• Cell count with differential
• Protein concentration
• Culture and sensitivity
• PMN count to diagnose SBP 2, 3, 4 Note that the specific fluid studies required may vary depending on the clinical context and the suspected underlying condition.