In pyogenic liver abscess commonest route of spread

"Along with cryptogenic infections, infections from the biliary tree are presently the most common identifiable cause of the hepatic abscess. Biliary obstruction results in bile stasis, with the potential for subsequent bacterial colonization, infection and ascension into the liver. This process is k/a ascending suppurative cholangitis. The nature of biliary obstruction is mostly related to stone disease or malignancy. In Asia, intrahepatic stones and cholangitis (recurrent pyogenic cholangitis) is a common cause, whereas, in the Western world, malignant obstruction is becoming a more predominant factor" Ref : Sabiston 18/e p1485