Spontaneous bacterial peritonitis (SBP) is a frequent complication in cirrhotic patients with ascites. Diagnosis of SBP is established by a polymorphonuclear cell count in ascitic fluid > or =250 cells/mm(3).
Indications for diagnostic paracentesis.
- Cirrhotic patients with ascites at admission
- Cirrhotic patients with ascites and signs or symptoms of infection: fever, leukocytosis, abdominal pain
- Cirrhotic patients with ascites who present with a clinical condition that is deteriorating during hospitalization: renal function impairment, hepatic encephalopathy, gastrointestinal bleeding
- Patients with new-onset ascites
Analysis of Peritoneal Fluid
Test and Ascitic-Fluid Container | Comments |
Albumin | Differential diagnosis of ascites according to the serum–ascites albumin gradient |
Cell | Cell count and differential count |
Culture | Aerobic- and anaerobic-culture |
Additional Analyses of Ascitic Fluid
Test and Ascitic-Fluid Container | Comments |
Tube without additives | |
Total protein | Values >1 g/dl suggest secondary peritonitis instead of SBP |
Lactate dehydrogenase | Values greater than the upper limit of normal for serum suggest secondary peritonitis instead of SBP |
Glucose | Values <50 mg/dl suggest secondary peritonitis instead of SBP |
Carcinoembryonic antigen | Values >5 ng/ml suggest hollow viscus perforation |
Alkaline phosphatase | Values >240 U/liter suggest hollow viscus perforation |
Amylase | Values markedly elevated (often >2000 U/liter or five times serum levels) in patients with pancreatic ascites or hollow viscus perforation |
Triglyceride | Values >200 mg/dl suggest chylous ascites |
Syringe or evacuated container | |
Cytology | Sensitivity increased if three samples submitted and promptly evaluated |
Mycobacterial culture | Sensitivity only 50% |
Differential Diagnosis of Ascites According to the Serum–Ascites Albumin Gradient
Gradient >1.1 g/dl (portal hypertension) | Gradient <1.1 g/dl |
Cirrhosis Alcoholic hepatitis Cardiac ascites Portal-vein thrombosis Budd-Chiari syndrome Liver metastases |
Peritoneal carcinomatosis Tuberculous peritonitis Pancreatic ascites Biliary ascites Nephrotic syndrome Serositis |
The diagnosis of SBP is suggested by a polymorphonuclear (PMN) cell count in excess of 250 cells per cubic millimeter in the absence of evidence of an alternative source of infection (secondary peritonitis), such as viscus perforation or intraabdominal abscess.
Determination of total protein, lactate dehydrogenase, and glucose levels in ascitic fluid may aid in the differentiation between SBP and secondary peritonitis. Culture is used to confirm the diagnosis of SBP.
References:
- Fernandez J, Bauer TM, Navasa M, Rodes J. Diagnosis, treatment and prevention of spontaneous bacterial peritonitis. Baillieres Best Pract Res Clin Gastroenterol. 2000 Dec;14(6):975-990. [Medline]
- Thomsen TW, Shaffer RW, White B, Setnik GS. Videos in clinical medicine. Paracentesis. N Engl J Med. 2006 Nov 9;355(19):e21. [Medline]