This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
In pyogenic liver abscess commonest route of spread is - 
Select and explain. 
A. Hematogenous through poal vein., B. Ascending infection through biliary tract, C. Hepatic aery, D. Local spread
B: Ascending infection through biliary tract
Answer: B: Ascending infection through biliary tract 
Explanation: Ans is 'b' ie Ascending infection through biliary tract 'Along with cryptogenic infections, infections from the biliary tree are presently the most common identifiable cause of 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) are a common cause, whereas in the Western world, malignant obstruction is becoming a more predomiannt factor" - Sabiston