Transient elastography (XL probe) rapidly differentiates between hepatic and non-hepatic causes of ascites

Background: Measurement of liver stiffness (LS) by transient elastography (TE, Fibroscan) has revolutionized the non-invasive diagnosis of cirrhosis. Thus far, TE could not be performed in patients with ascites which has been an important exclusion criterion besides obesity. We here explore the novel more energetic XL probe in patients with ascites (cirrhotic and other causes) and in a ascites pig model.

Methods: We measured LS 15 patients with ascites due to hepatic or non-hepatic reasons using Fibroscan (XL probe). In addition, liver morphology, skin-capsula distance, diameter of ascites lamella were obtained by ultrasound. We further established an animal ascites model using German landrace pigs by abdominal liquid infusion through a laparoscopic trocar to test the influence of intraabdominal pressure on LS.

Results: LS could be measured all patients with ascites except one with a skin-capsula distance of 20mm. In the two patients with normal LS (<6 kPa) non-cirrhotic causes explained the ascites (portal vein thrombosis, biliary pancreatitis). In the other patients with known decompensated alcoholic liver cirrhosis, LS ranged from 7.8 kPa –75 kPa (mean 62 kPa). Within same patients, the diameter of the ascites lamella did not affect LS. We next confirmed in the animal ascites model that ascites per se and the accompanying increased intraabdominal pressure do not increase LS as long as hepatic venous outflow is not impaired.

Conclusion: TE (XL probe) reliably allows to determine LS in most patients with ascites. Ascites does not affect LS in the absence of liver congestion as can be confirmed by routine ultrasound (hepatic and caval vein diameter). Thus, TE rapidly identifies patients with non-hepatic causes of ascites that otherwise undergo multiple, long lasting and invasive diagnostic procedures.