The role of ascitic fluid viscosity in differentiating the nature of ascites and in the prediction of renal impairment and duration of ICU stay.

BACKGROUND AND AIM: Serum-ascites albumin gradient (SAAG) has been used in the classification of ascites for the last 20 years but it has some drawbacks. This study searches for possible correlations between ascitic fluid viscosity and the etiology of ascites, renal impairment, and length of ICU stay.

MATERIALS AND METHODS: The study was conducted in Zagazig University Hospital, Egypt. It included 240 patients with ascites due to various causes. The patients were divided into two groups: the cirrhotic ascites group, which included 120 patients, and the noncirrhotic ascites group, which included 120 patients. Ascitic patients on medical management with diuretics, antibiotics, paracentesis, and infusion of plasma or albumin were excluded.The laboratory analysis included routine investigations to detect the cause of ascites as well as specific investigations such as ascitic fluid viscosity using a falling ball viscosimeter (microviscosimeter) at 37°C.

RESULTS: The mean ascitic viscosity of patients with SAAG at least 1.1 was 1.16±0.56, which was associated with serum creatinine 1.35±0.52 mg/dl and ICU stay of 3.3±1.2 days. In patients with SAAG less than 1.1 g/dl, the mean ascitic viscosity was 2.98±0.87, with serum creatinine 2.1±0.56 mg/dl and ICU stay of 7.1±1.3 days. Ascitic viscosity can discriminate ascites due to portal hypertension from those associated with nonportal hypertension at a cut-off value of 1.65; it can predict renal impairment in hepatic patients at a cut-off of 1.35 and long ICU stay at a cut-off of 1.995 using receiver operating characteristic analysis.

CONCLUSION: Ascitic viscosity measurement is rapid, inexpensive, and requires small sample volumes. Ascitic viscosity can discriminate ascites due to portal hypertension from those associated with nonportal hypertension at a cut-off value of 1.65. It can predict renal impairment in hepatic patients at a cut-off of 1.35 and long ICU stay at a cut-off of 1.995.