Secondary bacterial peritonitis should be ruled out either clinically, radiographically or by ascitic fluid analysis before the diagnosis of spontaneous bacterial peritonitis is made
Peritoneal fluid analysis suggesting perforated viscus
Peritoneal fluid with CEA >5ug/L or ALP >240units/L are suggestive of secondary peritonitis (sensitivity and specificity of ~90%).
These patients should undergo an urgent assessment for a surgical cause of abdominal infection.
Diagnosis of spontaneous bacterial peritonitis: 0.25x10⁹/L (>250/uL) neutrophils in ascitic fluid
Clinical features include fever, abdominal pain and altered mental status
Do not wait for culture before treatment
If clinical picture is highly suggestive of SBP, but the PMN count is less than 0.25x10⁹/L (250/uL), continue empiric therapy until a negative culture result
For optimal sensitivity, collect 5-10mL ascitic fluid into both an aerobic and anaerobic blood culture bottle or 10mL into a sterile container.