Malignant obstructions of the bile duct are not rare. The most common and accepted method for biliary drainage is endoscopic stent placement. There are three types of metal stents: fully covered (FC), partially covered (PC) and uncovered (U). PC-SEMS have been recently introduced and compared to FC-SEMS they seem to have a lower risk of migration, although data in the literature are discordant. Therefore the investigators will randomize the participants with biliary obstruction in 2 groups according to the type of stent used: PC-SEMS or U-SEMS. After metallic biliary stent insertion, enrolled patients will be followed for 12 months.

Malignant obstructions of the bile duct are generally caused by: adenocarcinoma of the Vater ampulla, pancreas head cancer, cholangiocarcinoma and external compression secondary to lymph node (LN) metastasis. The management of jaundice and cholangitis, as a result of bile stenosis, is crucial in this group of patients. The most common and accepted method for biliary drainage is endoscopic stent placement with plastic stents or self-expandable metal stents (SEMS). In recent times, the use of SEMS has become more common as it provides longer times of patency and a reduced risk of adverse events such as cholangitic episodes. There are three types of metal stents: fully covered (FC), partially covered (PC) and uncovered (U). PC-SEMS have been recently introduced and compared to FC-SEMS they seem to have a lower risk of migration, however different randomized and non-randomized studies have compared the outcome of U-SEMS vs FC-SEMS with between uncovered and covered stents have produced different results regarding the cumulative patency of stents and endoscopic re-intervention rates. To date, there are few and discordant prospective data on the outcomes of PC-SEMS use in malignant biliary obstructions.

Therefore, the investigators will randomize the participants with biliary obstruction in 2 groups according to the type of stent used: PC-SEMS or U-SEMS (T0 timing).

Then the participants will be followed for total period of 12 months. 2 different timings of follow-up will be considered:

- T1: it will start after stent insertion. The biliary drainage will be considered effective, according to the European guidelines, when the bilirubin values will be < or = 2 mg/dl for a period of at least 6 weeks if the initial bilirubin values were higher than 10 mg/dl or 3 weeks if at the beginning were lower than 10 mg/dl; After this first phase, all the enrolled patients will be divided in 2 groups according to their "fitness" for chemiotherapy: FIT and UNFIT Group.

FIT group: blood test (including total bilirubin, gamma-GT) will be done for follow-up study once every three months.

UNFIT Group: blood test (including total bilirubin, gamma-GT) will be done for follow-up study after 3, 9 and 12 months.

Inclusion Criteria:

•The patients who had malignant biliary obstruction with a estimated survival >4 months

Exclusion Criteria:

• The patients who had resectable biliary malignancy
• The patients who had hilar obstruction
• The patients who had duodenal obstruction
• The patients who had International Normalized Ratio (INR)>1.5
• The patients who did not give informed consent
• The patients who had technically difficult structure for Endoscopic retrograde cholangiopancreatography (ERCP)