Duplex Doppler ultrasound examination of the portal venous system: an emerging novel technique for the estimation of portal vein pressure.
Measurement of portal venous pressure in patients with portal hypertension is important to assess efficacy of beta blockers in patients with esophageal varices. Currently, the gold standard for measurement of portal venous pressure is the estimation of hepatic venous pressure gradient (HVPG). Being an invasive technique, serial measurements of HVPG are not feasible in clinical practice. In this respect, duplex Doppler ultrasound (DDUS) examination is an upcoming non-invasive technique for the estimation of portal venous and splanchnic hemodynamics. The aim of the present review is to analyze the current literature focusing on how the two techniques compare to each other in terms of assessing the portal pressure and assessing pitfalls in the current technique. Duplex Doppler ultrasound (DDUS) currently has limitations in measuring the portal pressure in a non-invasive way. Hemodynamic venous and arterial indices measured on DDUS correlate with the HVPG. The technique has been refined, however, there is no uniform surrogate marker that can be used in clinical practice. More studies are needed in order to remove the shortcomings in the current technique. The target is to be able to measure the actual portal pressure or at least derive an ideal venous or arterial hemodynamic surrogate marker having close correlation with the HVPG.