<qa>  What is the cause of secondary sclerosing cholangitis?- Presence of documented secondary sclerosing cholangitis such as ischemic cholangitis, recurrent pancreatitis, intraductal stone disease, severe bacterial cholangitis, surgical or blunt abdominal trauma, recurrent pyogenic cholangitis, choledocholithiasis, toxic slerosing cholangitis due to chemical agents, or any other cause of secondary sclerosing cholangitis on prior clinical investigations 