Another pitfall for spontaneous bacterial peritonitis

A reader addresses a previous column on a diagnostic pearl.

I would like to add to Drs. Olson's and Astik's recent pearl about spontaneous bacterial peritonitis in the February 2023 ACP Internist (“Being Deliberate about Spontaneous Bacterial Peritonitis”) by discussing the serum-ascites albumin gradient (SAAG). In addition to the pitfall of applying the criterion of 250 neutrophils per cubic millimeter to patients with ascites without portal hypertension in diagnosing spontaneous bacterial peritonitis, a major pitfall in the diagnostic approach to the patient with ascites is not determining the SAAG.

Ascites with a SAAG of 1.1 or greater, as seen in patients with cirrhosis, is highly suggestive of the presence of portal hypertension, whereas a SAAG below 1.1, as seen in patients with, for example, tuberculous ascites and malignant ascites, indicates the absence of portal hypertension, as described in 2021 practice guidance on ascites, spontaneous bacterial peritonitis, and hepatorenal syndrome from the American Association for the Study of Liver Diseases. All too often a diagnostic paracentesis is performed without determination of ascitic albumin, complicating the approach to the patient with ascites.

Richard H. Moseley, MD, FACP
Boulder, Colo.