Percutaneous transhepatic biliary drainage (PTBD) is a drainage method for biliary obstruction. Patients with a PTBD catheter often need multiple re-interventions because of symptoms of catheter obstruction such as pain, jaundice, pruritus, leakage and/or fever. The onset of these symptoms results in hospital visits, opening of the external catheter of an internal external PTBD and re-interventions. The investigators hypothesize that daily flushing of an internal external biliary catheter will increase the time-to-symptom-onset.