The most common pre-hepatic cause is portal vein obstruction, like when there's a thrombus occluding the portal vein and blocking blood flow.

最常见的肝前型病因是门静脉阻塞，例如当有栓子阻塞门静脉血流时。

Here's a pretty basic layout of the basic functional unit of the liver, you've got the portal vein and hepatic artery that combine into a sinusoid, which then goes into the central vein, and these are all lined with hepatocytes.

这是一个肝脏基本功能单位的简单示意图，你可以看到由门静脉和肝动脉来的血液在血窦汇集，然后流入中央静脉，这些都与干细胞相平行。