From the Guidelines
No, the total nucleated cell count is not the same as the neutrophil count in diagnosing spontaneous bacterial peritonitis (SBP). The total nucleated cell count includes all white blood cells present in the ascitic fluid, including neutrophils, lymphocytes, monocytes, and other white cell types. In contrast, the neutrophil count specifically measures only the neutrophils, which are the primary cells involved in acute bacterial infections. For diagnosing SBP, the standard diagnostic criterion is an absolute neutrophil count ≥250 cells/mm³ in ascitic fluid, not the total cell count, as stated in the guidelines on the management of ascites in cirrhosis 1. This distinction is clinically important because SBP is characterized by neutrophilic predominance in the ascitic fluid. When evaluating a patient with suspected SBP, physicians should specifically request and review the neutrophil count rather than relying solely on the total cell count, as a high lymphocyte count (which would increase the total count) does not indicate SBP.
Some key points to consider in the diagnosis and management of SBP include:
- Diagnostic paracentesis should be carried out without delay to rule out SBP in all cirrhotic patients with ascites on hospital admission 1.
- The diagnosis of SBP is based on neutrophil count in ascitic fluid of >250/mm3 1.
- Empirical antibiotic therapy must be initiated immediately after the diagnosis of SBP, considering the severity of infection and local resistance profile 1.
- Treatment should be initiated promptly when the neutrophil threshold is met, typically with a third-generation cephalosporin like ceftriaxone 1-2g IV daily for 5-7 days, or alternatives such as ciprofloxacin in patients with penicillin allergies.
It's also important to note that the use of reagent strips for rapid diagnosis of SBP is not recommended due to low diagnostic accuracy 1. Additionally, the management of SBP may involve the use of intravenous albumin to reduce the incidence of renal impairment and death, as shown in some studies 1. However, the most recent and highest quality study should always be prioritized when making a definitive recommendation. In this case, the guidelines on the management of ascites in cirrhosis 1 provide the most up-to-date and evidence-based recommendations for the diagnosis and management of SBP.
From the Research
Total Nucleated Cells vs Neutrophil Count
- The total nucleated cell count is not the same as the neutrophil count in diagnosing spontaneous bacterial peritonitis (SBP) 2, 3.
- A study found that a total ascitic nucleated cell count less than 1.0 g/l is unlikely to represent SBP, with a negative predictive value of 95.5% 3.
- Another study stated that the diagnosis of SBP is set in neutrophilic leukocytes in ascites ≥ 250 cells/mm3, as bacterial cultures are positive in only 16% of them 4.
Diagnostic Criteria
- The diagnostic criteria for SBP include a polymorphonuclear (PMN) cell count in the ascitic fluid greater than 0.250 g/l determined via cytological (microscopic) examination 2, 4.
- A total ascitic nucleated cell count can be used to exclude SBP, but it is not a definitive diagnostic criterion 3.
- Other studies have proposed the use of reagent strips measuring leukocyte esterase activity as a rapid and inexpensive alternative to diagnose SBP 5.
Comparison of Diagnostic Methods
- The diagnostic accuracy of leucocyte esterase reagent strips read out by a photospectrometer was found to be higher than visual interpretation, and was excellent for excluding SBP 5.
- A study compared the diagnostic accuracy of total ascitic nucleated cell count with PMN count, and found that the total ascitic nucleated cell count is not a reliable substitute for PMN count in diagnosing SBP 3.