Spontaneous bacterial peritonitis in adults: Diagnosis
- Bruce A Runyon, MD
Bruce A Runyon, MD
- Section Editor — Cirrhosis and Its Complications
- Clinical Professor of Medicine
- University of New Mexico, Division of Gastroenterology and Hepatology
- Special Hepatology Consultant to the Indian Health Service
- Northern Navajo Medical Center, Shiprock, New Mexico
Spontaneous bacterial peritonitis (SBP) is defined as an ascitic fluid infection without an evident intra-abdominal surgically treatable source . 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.
OVERVIEW OF DIAGNOSTIC APPROACH
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 . 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 . 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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- http://www.aasld.org/practiceguidelines/Documents/ascitesupdate2013.pdf (Accessed on April 23, 2013).
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- OVERVIEW OF DIAGNOSTIC APPROACH
- OBTAINING ASCITIC FLUID
- Handling the ascitic fluid
- - Culture
- - Gram stain
- - Cell count
- - Chemistries
- INTERPRETATION OF ASCITIC FLUID TEST RESULTS
- Culture and Gram stain results
- Ascitic fluid cell count
- Ascitic fluid chemistries
- - Serum-ascites albumin gradient
- - Ascitic fluid total protein concentration
- - Ascitic fluid glucose concentration
- - Ascitic fluid lactate dehydrogenase
- - Ascitic fluid amylase
- - Ascitic fluid bilirubin concentration
- Investigational tests
- Unhelpful tests
- DISTINGUISHING SPONTANEOUS FROM SECONDARY BACTERIAL PERITONITIS
- Clinical signs and symptoms
- Ascitic fluid analysis
- Imaging studies
- Response to treatment
- Peritonitis developing during antibiotic treatment
- Other conditions masquerading as secondary bacterial peritonitis
- DISTINCTION FROM ALCOHOLIC HEPATITIS
- SUMMARY AND RECOMMENDATIONS