A 48-year-old male who is 1 month status postorthotopic liver transplant for NASH Cirrhosis is transferred to the ICU with abdominal distention, pain, and septic shock. He has a known history of duodenal ulcer. A computed tomography (CT) of the abdomen and pelvis does not show any obvious free air or perforation. Sepsis guidelines are followed, and the decision is to proceed with a diagnostic paracentesis. The fluid drained does not contain any bile staining.
Which one of the answers below supports a spontaneous bacterial peritonitis rather than a secondary bacterial peritonitis?A. Ascites protein concentration of less than 1 g/dL
Correct Answer: A
When there is a clinical concern for the diagnosis of primary versus secondary bacterial peritonitis, cell counts and cultures often do not help to differentiate. In these diagnostic dilemmas examination of fluid chemistries may help with the diagnosis. Although when the serum-ascites albumin gradient (SAAG) is greater than 1.1 g/dL is highly suggestive of portal hypertension with 97% accuracy, it does not help differentiate between primary versus secondary bacterial peritonitis alone. Measure of the ascites fluid total protein concentration can often provide additional diagnostic clues. Patients with the most “dilute” ascites have the lowest level of opsonins, which puts them at the highest risk of spontaneous bacterial peritonitis. Ascites fluid protein concentration less than 1 g/dL correlates inversely with higher risk of developing spontaneous bacterial peritonitis. Additionally, neutrophils consume large amounts of glucose and thus ascites glucose concentration generally remains above 50 mg/dL in spontaneous bacterial peritonitis. But this number often falls below this level in secondary bacterial peritonitis, which can help with the diagnosis. In bowel perforations, the levels may fall to as low as zero. Ascites fluid lactate dehydrogenase (LDH) in the ascites fluid is released when the PMNs have been lysed. The LDH numbers rise in spontaneous bacterial peritonitis, but their numbers increase even further in secondary bacterial peritonitis. The upper limit varies but LDH levels in sterile ascites generally range between 40 ± 20 units/L. Amylase levels are elevated in the ascites fluid with pancreatitis and bowel perforation supporting a secondary bacterial peritonitis.