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Spontaneous bacterial peritonitis in adults: Diagnosis

Bruce A Runyon, MD
Section Editor
Keith D Lindor, MD
Deputy Editor
Kristen M Robson, MD, MBA, FACG


Spontaneous bacterial peritonitis (SBP) is defined as an ascitic fluid infection without an evident intra-abdominal surgically treatable source [1]. The presence of SBP, which almost always occurs in patients with cirrhosis and ascites, is suspected because of suggestive signs and symptoms, such as fever, abdominal pain, or altered mental status (table 1), though some patients are asymptomatic and are detected when they undergo paracentesis after being admitted to the hospital for another reason. (See "Spontaneous bacterial peritonitis in adults: Clinical manifestations".)

This topic will review the diagnosis of SBP, as well as distinguishing SBP from secondary bacterial peritonitis or alcoholic hepatitis with ascites. The performance of paracentesis, the pathogenesis, clinical manifestations, and treatment of SBP, and the general evaluation of adults with ascites are discussed elsewhere. (See "Diagnostic and therapeutic abdominal paracentesis" and "Pathogenesis of spontaneous bacterial peritonitis" and "Spontaneous bacterial peritonitis in adults: Clinical manifestations" and "Spontaneous bacterial peritonitis in adults: Treatment and prophylaxis" and "Spontaneous bacterial peritonitis variants" and "Evaluation of adults with ascites".)

In 2013, the American Association for the Study of Liver Diseases updated its guideline on the management of adult patients with ascites due to cirrhosis (table 2) [2,3]. The discussion that follows is consistent with that guideline.


Spontaneous bacterial peritonitis (SBP) should be suspected in patients with cirrhosis who develop signs or symptoms such as fever, abdominal pain, altered mental status, abdominal tenderness, or hypotension (table 1). In addition, patients with ascites admitted to the hospital for other reasons should also undergo paracentesis to look for evidence of SBP. A low clinical suspicion for SBP does not obviate the need for testing [4]. Paracentesis can be performed in the interventional radiology suite or at the bedside. It is important that trained personnel be available to perform the procedure at off hours (such as at night or on weekends). Paracentesis should be carried out promptly in patients with suspected SBP, as delays in performing paracentesis have been associated with increased mortality. (See 'Paracentesis' below and "Spontaneous bacterial peritonitis in adults: Clinical manifestations", section on 'Clinical manifestations' and "Diagnostic and therapeutic abdominal paracentesis".)

The importance of paracentesis was demonstrated in a review of a database of 17,711 patients with cirrhosis and ascites who were admitted to the hospital with a primary diagnosis of ascites or encephalopathy [5]. Paracentesis was performed in 61 percent. Patients who underwent paracentesis had a lower in-hospital mortality rate than those who did not undergo paracentesis (6.5 versus 8.5 percent; adjusted odds ratio 0.55, 95% CI 0.41-0.74).

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Literature review current through: Nov 2017. | This topic last updated: Aug 17, 2015.
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