American Board of Internal Medicine (ABIM) Certification Practice Exam

Which factor is NOT included in the criteria for diagnosing SBP in patients with cirrhosis?

1. Cirrhosis

2. Child-Pugh score of 8

3. Blood urea nitrogen level under 20

4. Serum creatinine level of 1.2 or greater

The correct answer is: Blood urea nitrogen level under 20

The diagnosis of spontaneous bacterial peritonitis (SBP) in patients with cirrhosis relies on a combination of clinical criteria and laboratory findings. In this context, the correct choice reflects a factor that is not part of this diagnostic process. Cirrhosis is a necessary condition required in the diagnosis of SBP, as the condition occurs primarily in patients with cirrhosis. Similarly, the Child-Pugh score is a scoring system used to assess the severity of liver disease and is relevant in evaluating patients for various complications, including SBP. A score of 8 is indicative of intermediate liver disease, which can increase the risk of complications such as SBP. Another critical diagnostic marker is the serum creatinine level, which helps assess renal function in the context of SBP. A level of 1.2 or greater is particularly relevant, as it signals a potential deterioration in kidney function which may accompany bacterial infections in cirrhotic patients. On the other hand, a blood urea nitrogen (BUN) level under 20 is not specifically indicative of SBP and does not serve as a criterion for diagnosis. BUN levels may vary for many reasons and are not a direct marker of infection within the ascitic fluid. Therefore,