It is predominantly now performed as a therapeutic technique. There are less invasive means of imaging the biliary tree including transabdominal ultrasound, magnetic resonance cholangiopancreatography, computed tomography and endoscopic ultrasound. If the biliary system is obstructed, PTC may be used to perform biliary drainage until a more permanent solution for the obstruction is performed (e.g. surgery). Additionally, self expanding metal stents can be placed across malignant biliary strictures to allow palliative drainage. Percutaneous placement of metal stents can be utilised when therapeutic ERCP has been unsuccessful, anatomy is altered precluding endoscopic access to the duodenum, or where there has been separation of the segmental biliary drainage of the liver, allowing more selective placement of metal stents. It is generally accepted that percutanous biliary procedures have higher complication rates than therapeutic ERCP. Complications encountered include infection, bleeding and bile leaks.