Tap the ascites on every admission, not on suspicion

A patient with cirrhosis and ascites who is admitted for any reason should have a diagnostic paracentesis, whether or not they have abdominal pain, fever or a raised white cell count. Spontaneous bacterial peritonitis presents without any of those in a substantial proportion of cases, and the presentation is often nothing more specific than encephalopathy, renal deterioration, or simply being less well.

A diagnostic tap is 20 to 30 mL, takes a few minutes at the bedside with ultrasound, and needs cell count with differential plus culture in blood culture bottles inoculated at the bedside — the last of those being where the yield is most often lost. A neutrophil count of 250 per mm³ or more starts treatment, regardless of what the culture eventually grows.

The reason to make this automatic rather than clinical-judgement-driven is that the judgement is the part that fails. The patient who deteriorates without an obvious precipitant is precisely the patient in whom the diagnosis is being missed, and by the time suspicion is high enough to prompt the tap, the delay has already happened.

• Perform diagnostic paracentesis on every admission with ascites, symptoms or not
• Inoculate blood culture bottles at the bedside; delayed inoculation loses the organism
• Treat at a neutrophil count of 250 per mm³ or above, without waiting for culture
• Repeat the tap if the patient deteriorates later in the admission
• Record that it was done — the omission is usually invisible in the notes

Why it matters

The patients in whom spontaneous bacterial peritonitis is missed are the ones who do not look infected, which is most of them.

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