Metallic Stents for Benign Extrahepatic Biliary Stricture: In Praise of Self-Expansion?
Benign biliary strictures are often safely and successfully treated with removable indwelling biliary stents with stricture resolution in 75–90 % of all cases. There is no consensus on the optimal time to remove the stent, and this typically varies from 3 to 12 months [1, 2], depending upon the pathology of the stricture and the clinical setting. For example, shorter dwell times are recommended for post-orthotropic liver transplant (OLT) strictures in the setting of immunosuppression. Resolution of the stricture must be balanced against the complications of stent migration and of cholangitis.
Examples of the etiologies benign biliary strictures amenable to temporary biliary stenting
Post-OLT anastomotic stricture
Primary sclerosing cholangitis
Potential flaws of the study include its retrospective nature with variable lengths of follow-up, heterogeneity of stricture etiology, and the tertiary hospital case mix, all factors that may reduce generalizability. The strength of the study is that it suggests that a 6-month stent dwell time may be optimal.
Self-expanding metal stents have been increasingly used in preference to plastic stents. In a systematic review of the treatment of chronic pancreatitis-related biliary strictures, the use of covered self-expanding metal stents achieved higher success rates than plastic stents as well as lower complication rates . On the other hand, another systematic review identified a higher complication rate associated with the use of self-expanding metal stents (40 %) compared to either single (36 %) or multiple plastic stents (20 %) . Another relatively recent prospective multicenter study of 133 patients reported that stent duration of >90 days increased stricture resolution rate by 4.3-fold . The benefit of self-expanding metal stents, however, has not been reported for all aetiologies of benign strictures; hence, further research is needed in this expanding field.
Stent migration, another cause for failure to achieve the scheduled dwell time, occurs in up to 37 % of procedures . Efforts to decrease migration include the incorporation of anti-migration features to the stent such as flared ends, anchoring flaps, and a novel unfixed cell structure design . In comparison with stenting of malignant strictures, self-expanding covered metal stents are more cost-effective with palliative etiologies since stent replacement is rarely indicated. Any future prospective randomized studies should stratify for stricture etiology, stent type, and health economic benefits need to be determined.
In conclusion, endoscopic stent placement is increasingly recognized as the standard of care in the treatment of benign biliary strictures. Treatment efficacy is high, especially if the indwelling stent time is not interrupted by early occlusion or migration. A scheduled stent removal time of 6 months seems reasonable as an appropriate compromise between improving the stricture resolution rate and limiting the risk of cholangitis.
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- 5.Siiki A, Helminen M, Sand J, Laukkarinen J. Covered self-expanding metal stents may be preferable to plastic stents in the treatment of chronic pancreatitis-related biliary strictures: a systematic review comparing 2 methods of stent therapy in benign biliary strictures. J Clin Gastroenterol. 2014;48:635–643.CrossRefPubMedGoogle Scholar
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