Fig.1

SV/SPV splenic vein, IVC inferior vena cava, PV portal vein, SMV superior mesenteric vein, LRV left renal vein. Patient 1a Superior mesenteric vein and splenic vein converge into portal vein, and portal vein directly flows into inferior vena cava. Patient 2b Superior mesenteric vein, splenic vein and left renal vein converge into portal vein, most of the portal vein flows into inferior vena cava, and another slender branch enters the liver. Patient 3c Most of the portal vein flows into the inferior vena cava through the left lobe of the liver, and a few into the liver. Patient 4d The branch of portal vein drains into inferior vena cava. Patient 5e Part of the portal vein flows into the inferior vena cava through the iliac vein. Patient 6f: Superior mesenteric vein and splenic vein converge into portal vein, the left branch of portal vein enters inferior vena cava and the right branch of portal vein enters liver