The purpose of this study is to retrospectively assess the importance of initial bile duct puncture angle on total fluoroscopy time and overall efficacy during ultrasound and fluoroscopy guided percutaneous transhepatic biliary drainage (PTBD) performed for patients with malignant biliary hilar obstruction.

Data used for this study will be collected from medical records of patients who underwent PTBD at the Interventional radiology department. Only patients who received percutaneous biliary drainage performed with right sided intercostal approach will be included in study. The initial puncture was ultrasound-guided in all patients. Any subsequent step of the procedure was performed under fluoroscopy. The cumulative fluoroscopy time (the total time of the exposure to X rays during intervention) after the US guided puncture was recorded. It will be used as an indirect measure of the complexity of the intervention and as an important parameter of radiation exposure. The patients will be divided into two groups based on the puncture angle: ≤30° group and >30° group. The two groups will be retrospectively analysed for technical success, fluoroscopy time and complications.

Inclusion Criteria:

• pathological confirmation or imaging data confirming malignant disease causing bile duct obstruction, performance status 0-1.

Exclusion Criteria:

• terminally ill patiens, performance status ˃2, hepatic decompensation (including ascites), severe underlying cardiac or renal diseases and coagulation disorders

Patients with malignant biliary obstruction who underwent PTBD performed by right sided intercostal approach (US and fluorocopy guided).