Stent migration

Stent migration into the intrahepatic ducts may contribute to recurrent cholangitis or obstruction. Although this complication is rare, retrieval of a migrated stent may prove challenging. Using a variety of techniques, 80% of stents can be successfully retrieved endoscopically (Lahoti et al. 1998 O Connor 2000). (Fig. 1.11)... 

Recurrent dysphagia occurs in 10%-36% of patients and maybe due to stent migration, food bolus obstruction, or recurrent strictures due to tumor ingrowth, tumor overgrowth (Acunas et al. 1996 Cwikiel et al. 1998 Song et al. 1994 Laasch et al. 1998 Saxon et aL 1995 Morgan et al. 1996 Bartelsmann et al. 2000). 

Early recurrent obstruction most commonly is due to kinking or stent shortening and stent migration, whereas late reobstruction is usually due to tumour progression, either tumour overgrowth or tumour ingrowth. All these conditions usually can readily be treated with additional stent placement. 

Perforation, stent migration and inadequate bowel decompression are the major procedure-... 

To keep the migration rate as low as possible stent diameters of not less than 22-25 mm and a length of at least 6 cm seem advisable. Future developments such as an improved longitudinal flexibility and flared or bulbous ends may help to decrease the risk of stent migration. 

Treatment of stent occlusion includes local thrombolysis, thrombectomy, balloon dilatation and placement of additional stents. The possible causes of occlusion are intraluminal tumor growth, or tumor growth at the free ends of the stent as a consequence of insufficient coverage of the strictures by the stent, vessel contraction, and inadequate stent diameter leading to distal stent migration (Figs. 5.11, 5.12). 

Stent migration can occur but is rare in malignant disease. 

Covered Wallstents have a complication profile similar to plastic tube stents. Bolliger et al. (1996) found retained secretions in five out of 27 patients, granuloma formations at the stent ends in four, and stent migration in four. 

In the study from England by Madden et al (2002), complications occurred in seven out of 25 patients. Mucus retention was noted in four patients, respiratory infection occurred in four, and one patient developed a granuloma at the distal stent end, which was treated with laser ablation. No stent migration was noted in this series. 

For patients undergoing stent-assisted coil embolization of broad-based aneurysms, early recognition of procedure-related complications may be essential, such as incomplete stent deployment, stent migration during the coiling, or intracranial hemorrhage due to perforation of the aneurysm or the parent artery. 

Stent migration occurs if the stent is not adequately positioned or if it is not the correct length. This problem is avoided by careful technique and accurate measurement of ureteral length and selection of a stent of appropriate diameter and length. When stents are too long, bladder irritation will occur. If unavoidable, bladder spasm can be treated with urinary anesthetics such as pyridium. 

Late recurrent dysphagia may be due to stent migration or to tumour overgrowth below or, much more frequently, above the stent (Fig. 11.6). In situations where the overgrowth has occurred above the level of the stent, stent removal may prove impossible and over-stenting with a second stent will be necessary. Other techniques to deal with tumour overgrowth such as alcohol injection, laser photocoagulation or photodynamic therapy may also be appropriate. 

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