LAUSR

We read with great interest the article by Hartery et al entitled “Covered self-expanding metal stents for the management of common bile duct stones.” This retrospective study evaluated the safety and efficacy of inserting covered self-expanding metal stents (CSEMSs) alongside “difficult” stones in 44 patients at 2 tertiary referral centers. After the work by Cerefice et al in 2011, this is the second case series in the literature that has evaluated this modality in treating difficult stones after failed endoscopic extraction. In our unit, we have also been evaluating the role of CSEMSs in managing difficult stones in the common bile duct (CBD) after the failure of conventional therapy. The provisional data from our prospective case series (30 months) have shown favorable outcomes in line with the results of Hartery et al, with the notable difference that all cases were performed at a large district general hospital in North London, United Kingdom (CBD clearance 98% with the use of standard extraction techniques). Hitherto we have inserted 6 CSEMSs for large impacted stones (average diameter 28 mm, range 14-35 mm). Bile duct clearance was achieved in all patients: 5 patients after a single CSEMS insertion and 1 patient after a second period of CSEMS insertion (35-mm stone). The average duration of stent deployment was 60 days, which is slightly longer than those reported by both Hartery et al (56 days) and Cerefice et al (45 days). Thus far, procedural adverse events have not been identified. Our provisional results further corroborate the conclusions of those other two groups that CSEMS insertion is an effective and safe technique in removing difficult stones. Moreover, our study highlights that referrals to tertiary centers can be eliminated by the introduction of this modality alongside standard extraction techniques in a district general hospital. We entirely agree that large, multicenter, randomized controlled studies will help answer some of the questions around cost benefit and required duration of stent insertion.