<prompt> Which of the following is the commonest cause for biliary stricture?Trauma during surgeryCholangio carcinomaClonorchis infectionAutoimmune hepatitis  <response>: It is good to memorize the fact that procedures like ERCP can predispose to biliary strictures. Other causes include chronic inflammation secondary to gall stones, stenosis of sphincter of oddi or papillitis, cholangiohepatitis due to Opisthorchis sinesis or other parasites, cholangiocarcinoma, primary sclerosing cholangitis. 