The goal of this clinical randomized controlled trial is to perform primary percutaneous stenting (PPS) in patients with malignant hilar biliary obstruction (MHBO). The main question it aims to answer is:

To compare the efficacy of PPS above the ampulla to standard endoscopic biliary drainage (EBD) in patients with a MHBO who are ineligible for surgical resection.

Researchers will compare PPS with EBD to see if major complications within 90 days after randomisation occur.

Participants will undergo either primary percutaneous stenting or endoscopic biliary drainage, depending on randomization.

Inclusion Criteria:

• Written informed consent must be given according to ICH/GCP and national/local regulations.
• MHBO on imaging with histopathological confirmation or high clinical suspicion.
• Ineligible for surgical resection.
• Hyperbilirubinemia (a combination of a total bilirubin level >50 mmol/l.

Exclusion Criteria:

• Fluctuation or spontaneous decrease of a total bilirubin level before start of any treatment suggesting a potential non-malignant diagnosis.
• Patients who underwent previous biliary drainage procedures endoscopically or percutaneously. Patients who underwent an attempted but failed ERCP are eligible only when no papillotomy or cannulation was performed.
• Clinical signs of cholangitis. Cholangitis is defined as the presence of both fever (i.e. body temperature >38.5°C) and leucocytosis (i.e. ≥10 *109/L) without clinical or radiological evidence of acute cholecystitis (22).
• Uncorrectable coagulation disorder.
• Uncorrectable contrast allergy.