Aims: Novel ultrasound based elastography techniques (ARFI, Fibroscan) allow the measurement of liver stiffness (LS) in the presence of ascites. However, it is unclear whether ascites and concomitant elevation of intraabdominal pressure (IAP) increase LS.
Methods: LS was measured in 6 patients with ascites using the novel more powerful XL probe. In addition, LS was measured in narcotized German landrace pigs with intraabdominal saline liquid infusion to increase IAP. LS was then compared to central venous pressure (CVP) and IAP.
Results: LS was successfully measured in 6 patients despite ascites and skin capsule distance of up to 31mm. In two cases, no fibrosis seemed to be the underlying cause of ascites since LS was found to be normal (<6 kPa). Reasons for ascites in these two cases were portal thrombosis and peritoneal carcinomatosis. These findings suggest that ascites per se seems not to affect LS which could allow to discriminate between hepatic and non-hepatic causes of ascites. In a next set of experiments, we infused saline solution into the abdominal cave of narcotized pigs to elevate the IAP and determined LS. Despite an IAP of up to 25 mmHg, no increase of LS was observed. LS only increased if CVP exceeded IAP probably due to compression of the caval vein. Under these conditions, hepatic congestions was clearly visible using ultrasound. In addition, we generally observed that CVP slowly adapted to the increased IAP levels.
Conclusions: Ascites per se or an elevated intraabdominal pressure do not increase LS in the absence of liver congestion. Thus, valid LS measurements allow the rapid discrimination between hepatic and non-hepatic causes of ascites.
FibroScan - Liver stiffness - ascites - transient elastography - xl probe
