A prospective randomised study of "covered" versus "uncovered" diamond stents for the management of distal malignant biliary obstruction

Abstract

Background and aim: Covered self-expandable metal stents (EMS) were recently developed to overcome tumour ingrowth in conventional EMS. However, supporting evidence for the efficacy of covered EMS is lacking. Patients and methods: We enrolled 112 patients with unresectable distal biliary malignancies. They were randomly assigned to polyurethane covered (n = 57) or original diamond stent (n = 55). Results: Stent occlusion occurred in eight patients (14%) after a mean of 304 days in the covered group, and in 21 patients (38%) after a mean of 166 days in the uncovered group. The incidence of covered EMS occlusion was significantly lower than that of uncovered EMS (p = 0.0032). The cumulative stent patency of covered stents was significantly higher than that of uncovered stents (p = 0.0066). No tumour ingrowth occurred in the covered group while it was observed in 15 patients in the uncovered group. In subgroup analysis, the cumulative patency of the covered EMS was significantly higher in pancreatic cancer (p = 0.0363) and metastatic lymph nodes (p = 0.0354). There was no significant difference in survival between the two groups. Acute cholecystitis was observed in two of the covered group and in none of the uncovered group. Mild pancreatitis occurred in five of the covered group and in one of the uncovered group. Conclusions: Covered diamond stents successfully prevented tumour ingrowth and were significantly superior to uncovered stents for the treatment of patients with distal malignant biliary obstruction. However, careful attention must be paid to complications specific to covered self-expandable metal stents, such as acute cholecystitis and pancreatitis.

Risk factors for cholecystitis after metal stent placement in malignant biliary obstruction

“…[16][17][18] Also, recent reports documented an incidence of cholecystitis to be 5.8% to 11.5% with the use of covered stents. 9,14,15 Theoretically, the open interstices of the uncovered stents can allow sufficient GB drainage and avoidance of cholecystitis.…”

Spontaneous Common Bile Duct Perforation Treated with Placement of Metal Stent

“…6 However, whether uncovered or covered SEMS have superior stent patency period remains controversial. [7][8][9][10] One of the reasons for this may be because of differences between covering materials in membrane biodurability under long-term exposure to bile juice. 11 The reason that the stent patency period was shorter and the patency rate was lower than expected in some clinical studies of covered SEMS may be due to cracks in the covering membrane with subsequent tumor ingrowth (Fig.…”

To Drain or Not to Drain? That Is the Question

“…Regarding the type of stent, it is preferable to use SEMS in patients who are candidates for neoadjuvant therapies, since plastic stents are more prone to complications. Uncovered metal stents are preferred over covered stents, since covered SEMS are at higher risk inducing cholecystitis, migration, and more rarely pancreatitis [16][17][18][19]. Furthermore, given the experience of Aadam et al [9], SEMS should be chosen to be as short as possible in order to leave enough tissue for further anastomosis.…”