What are portosystemic collateral and their clinical manifestations?

Left gastric vein to the esophageal veins—esophageal varices Umbilical vein (via the falciform ligament) to the epigastric veins— caput medusa Superior hemorrhoidal vein to the middle and inferior hemorrhoidal veins—hemorrhoids Veins of Retzius (posterior abdominal wall veins) to the retroperitoneal lumbar veins—retroperitoneal varices