From the Guidelines
The most suggestive indicator of spontaneous bacterial peritonitis (SBP) is an elevated ascitic fluid polymorphonuclear (PMN) leukocyte count of ≥250 cells/mm³ in the absence of an obvious intra-abdominal source of infection. This finding is considered diagnostic for SBP and warrants immediate antibiotic treatment, even before culture results are available. Patients with suspected SBP should undergo diagnostic paracentesis to analyze the ascitic fluid. While other findings such as positive ascitic fluid culture, abdominal pain, fever, and altered mental status may be present, they are less reliable indicators. Approximately 10-30% of SBP cases have negative cultures despite elevated PMN counts (culture-negative neutrocytic ascites) 1.
Key Points
- The diagnosis of SBP is based on an ascitic fluid neutrophil count of >250/mm³ as determined by microscopy 1.
- Ascitic fluid culture is frequently negative even if performed in blood culture bottles and is not necessary for the diagnosis of SBP, but it is important to guide antibiotic therapy 1.
- Empirical antibiotic therapy should be started immediately following the diagnosis of SBP, with third-generation cephalosporins being the recommended first-line treatment 1.
- Early diagnosis and treatment are crucial as SBP carries significant mortality if not promptly addressed 1.
Recommendations
- Patients with ascites admitted to the hospital should undergo abdominal paracentesis to rule out SBP 1.
- Patients with ascitic fluid PMN counts greater than or equal to 250 cells/mm³ should receive empiric antibiotic therapy 1.
- The choice of antibiotic should be guided by local resistance patterns and the severity of infection 1.
From the Research
Spontaneous Bacterial Peritonitis Diagnosis
The diagnosis of spontaneous bacterial peritonitis (SBP) is primarily based on the analysis of ascitic fluid. Key indicators for SBP include:
- Neutrophil count in ascitic fluid
- Presence of bacterial infection
Diagnostic Criteria
The most suggestive indicator of SBP is:
- A neutrophil count greater than 250 cells/mm^3 in ascitic fluid 2, 3, 4, 5 This criterion is widely accepted and used in clinical practice to diagnose SBP.
Comparison of Options
Comparing the given options:
- A. Neutrophil > 250: This is the correct answer, as a neutrophil count greater than 250 cells/mm^3 is a well-established diagnostic criterion for SBP 2, 3, 4, 5.
- B. Lymphocyte > 250: This option is not a recognized diagnostic criterion for SBP. While lymphocytes may be present in ascitic fluid, their count is not typically used to diagnose SBP 2, 3, 4, 5.
Supporting Evidence
Studies have consistently shown that a neutrophil count greater than 250 cells/mm^3 in ascitic fluid is a reliable indicator of SBP 2, 3, 4, 5. This criterion has been validated through various diagnostic tests, including manual counting and flow cytometry 4. The use of dipstick tests has also been explored as a rapid and bedside diagnostic tool for SBP, with promising results 3.