 Thus, most of the bilirubin in the plasma becomes the conjugated type rather than the unconjugated type, and this conjugated bilirubin, which did not go to intestine to become urobilinogen, gives the urine the dark color.Bilirubinuria is due to excess conjugated bilirubin excreted in the urine.Post-hepatic jaundice (obstructive jaundice) is due to a blockage of bile excretion from the biliary tract → increased conjugated bilirubin and bile salts.