Diagnostic accuracy of serum ascites albumin gradient (SAAG) in a contemporary unselected medical cohort

Objectives To describe the different aetiologies of ascites and test the validity of serum ascites albumin gradient (SAAG) and cytology in a contemporary unselected medical cohort. Methods All adult patients admitted to Nottingham University Hospitals, UK, between 1 May 2013 and 30 April 2018 with new-onset radiologically-confirmed ascites were included. Data were analysed to determine the distribution of different aetiologies of ascites and the diagnostic accuracy of SAAG in portal hypertension and cytology in malignancy as underlying causes of ascites. Results Over 5 years, 286 patients presented with new-onset ascites; 122 surgical cases were excluded. Most patients were men (n = 84, 51.2%) over 50 years of age (n = 142, 86.6%). Cirrhosis accounted for 54.9% (n = 90) of the cases of ascites followed by malignancy (n = 48, 29.3%) and cardiac failure (n = 10, 6.1%). SAAG ≥11 g/L had a sensitivity of 85.5% and specificity of 60.6% for diagnosing portal hypertension as a cause of ascites (diagnostic accuracy = 78.5%, 95% confidence interval (CI): 69.8–85.5; area under the curve (AUC) = 0.756, 95% CI: 0.652–0.860). Ascitic fluid cytology was positive in 50% of malignant cases and 66% of primary peritoneal carcinomatosis cases. Conclusion The underlying aetiology and the validity of available tests varied substantially compared with previous reports.