Simple SummaryPancreatic ductal adenocarcinoma can cause distal bile duct obstruction. Fully covered biliary self-expandable metal stents (FCSEMSs) are widely used for bile duct drainage to prevent tissue ingrowth and can be easily exchanged. This retrospective study aimed to compare the efficacy of FCSEMSs placed in a first session of endoscopic retrograde cholangiopancreatography with that of FCSEMSs placed following a prior plastic stent. We also assessed the risk factors for recurrent biliary obstruction of FCSEMSs. We found that the time to recurrent biliary obstruction was comparable between the primary use of FCSEMSs and FCSEMSs with prior plastic stents. We also found that FCSEMS length was associated with dysfunction. These findings provide clinical evidence for the use of FCSEMSs in patients with pancreatic ductal adenocarcinoma and malignant distal obstruction.AbstractFully covered self-expandable metallic stents (FCSEMSs) are inserted in patients with unresectable pancreatic ductal adenocarcinoma (PDAC) to resolve malignant distal bile duct obstructions. Some patients receive FCSEMSs during primary endoscopic retrograde cholangiopancreatography (ERCP), and others receive FCSEMSs during a later session, after the placement of a plastic stent. We aimed to evaluate the efficacy of FCSEMSs for primary use or following plastic stent placement. A total of 159 patients with pancreatic adenocarcinoma (m:f, 102:57) who had achieved clinical success underwent ERCP with the placement of FCSEMSs for palliation of obstructive jaundice. One-hundred and three patients had received FCSEMSs in a first ERCP, and 56 had received FCSEMSs after prior plastic stenting. Twenty-two patients in the primary metal stent group and 18 in the prior plastic stent group had recurrent biliary obstruction (RBO). The RBO rates and self-expandable metal stent patency duration did not differ between the two groups. An FCSEMS longer than 6 cm was identified as a risk factor for RBO in patients with PDAC. Thus, choosing an appropriate FCSEMS length is an important factor in preventing FCSEMS dysfunction in patients with PDAC with malignant distal bile-duct obstruction.