Clinical role of non-invasive assessment of portal hypertension

Abstract

Measurement of portal pressure is pivotal in the evaluation of patients with liver cirrhosis. The measurement of the hepatic venous pressure gradient represents the reference method by which portal pressure is estimated. However, it is an invasive procedure that requires significant hospital resources, including experienced staff, and is associated with considerable cost. Non-invasive methods that can be reliably used to estimate the presence and the degree of portal hypertension are urgently needed in clinical practice. Biochemical and morphological parameters have been proposed for this purpose, but have shown disappointing results overall. Splanchnic Doppler ultrasonography and the analysis of microbubble contrast agent kinetics with contrast-enhanced ultrasonography have shown better accuracy for the evaluation of patients with portal hypertension. A key advancement in the non-invasive evaluation of portal hypertension has been the introduction in clinical practice of methods able to measure stiffness in the liver, as well as stiffness/congestion in the spleen. According to the data published to date, it appears to be possible to rule out clinically significant portal hypertension in patients with cirrhosis (i.e., hepatic venous pressure gradient ≥ 10 mmHg) with a level of clinically-acceptable accuracy by combining measurements of liver stiffness and spleen stiffness along with Doppler ultrasound evaluation. It is probable that the combination of these methods may also allow for the identification of patients with the most serious degree of portal hypertension, and ongoing research is helping to ensure progress in this field.

Keywords: Cirrhosis; Doppler ultrasound; Esophageal varices; Liver stiffness; Portal hypertension; Sonography; Splenic arterial resistance indices; Splenic stiffness; Transient elastography.

Figure 1

Hypothetical algorithm of non-invasive methods for screening and evaluation of clinically-significant portal hypertension and to discriminate patients with or without a need for endoscopic screening. CEUS: Contrast-enhanced ultrasonography; CSPH: Clinically-significant portal hypertension; DDU: Duplex Doppler ultrasonography; HVPG: Hepatic venous pressure gradient; LS: Liver stiffness; MRI: Magnetic resonance imaging; SHAPE: Subharmonic-aided pressure estimation; SS: Spleen stiffness; TE: Transient elastography.