How should I interpret the results of a diagnostic paracentesis in a patient suspected of having SBP?

When interpreting the results of a diagnostic paracentesis for a patient suspected of having spontaneous bacterial peritonitis (SBP), the primary indicator is the ascitic fluid neutrophil (polymorphonuclear leukocyte) count ¹, (McGibbon et al., 2007).

A neutrophil count of 250 cells/mm³ or more is diagnostic of SBP ¹, ², (McGibbon et al., 2007). Conversely, a neutrophil count of less than 250 cells/mm³ effectively rules out SBP (McGibbon et al., 2007).

In addition to the cell count and differential, ascitic fluid should also be sent for total protein and culture ¹, (McGibbon et al., 2007). It is important to note that ascitic fluid cultures are only positive in approximately 40% of SBP cases; therefore, a negative culture does not rule out SBP if the neutrophil count is elevated ¹, (McGibbon et al., 2007).

Prompt interpretation of these results is crucial for timely management, as SBP is a common and serious complication in patients with cirrhosis and ascites ².