Incidence of postprocedural cholecystitis after ERCP using a covered self-expandable metal stent (CSEMS) for distal malignant biliary obstruction (MBO) has been gradually reported. Without sufficient data, the recommendation for stent placement favors CSEMSs over uncovered self-expandable metal stents (USEMSs), with the tip placed below the cystic duct orifice. This study assessed the safety of CSEMSs versus USEMSs in the management of distal MBO.

All studies published up to December 2024 comparing adverse events after CSEMS and USEMS placement for biliary drainage were identified using PubMed, Embase, SCOPUS, and the Cochrane Library. Outcomes of interest were postprocedural cholecystitis, pancreatitis, stent migration, and tumor ingrowth. Pooled relative risks (RRs) with 95% CIs were calculated using a random-effect model. Subgroup analyses were performed based on study design and the presence of a gallbladder in situ.

Twenty-one studies (5753 patients) met inclusion criteria. The CSEMS group showed higher post-ERCP acute cholecystitis rates (RR, 1.71; 95% CI, 1.12-2.62), lower tumor in growth rates (RR, 0.13; 95% CI, 0.06-0.25), and higher rates of stent migration (RR, 7.53; 95% CI, 4.60-12.32). The difference was also demonstrated in subgroup analysis based on the presence of a gallbladder in situ.

Our study demonstrated higher rates of postprocedural cholecystitis following ERCP with CSEMS placement compared with USEMS placement. These findings highlight the importance of careful stent selection, particularly in patients with gallbladder in situ, to optimize patient care, reduce adverse events, and prevent delays in oncologic management.