Dislocation of coils during coil embolization is a quite rare complication but with possible vessel occlusion. The dislocation of coils occurs more frequently with usage of pushable coils in comparison to detachable coils due to the poor controllability. Dislocated coils occluding the blood flow in important vessels such as the CHA may be necessary to remove to avoid very rare but rather serious irreversible damage including acute hepatic failure (Aina et al. 2001). Recovery of dislocated coils with stent retrievers has been reported with various stent retrievers, including Solitaire (Medtronic, Minnesota, USA), Trevo (Stryker, Kalamazoo, MI) and Catch device (Balt, Montmorency, France). This method has proven to be highly effective in a few already published studies and case reports (Leslie-Mazwi et al. 2013; O'Hare et al. 2010; Liu et al. 2014; Hopf-Jensen et al. 2013; Kabbani et al. 2014).
The success rate in removal of dislocated coils in animals was over 99%, when trapping the coil between the stent retriever and the microcatheter was performed, regardless of the coil type, size and shape. In the same animal study, when the coil trapping maneuver was not applied, only 11% were successful (Nikoubashman et al. 2015a). This confirms our experience in this case where the coil was initially unsuccessful when the trapping maneuver was not used but efficiently removed as the microcatheter was advanced to trap the coil within the stent mesh of the pRESET. We do also recommend to unfold the stent retriever distally in the vessel with the dislocated coil being trapped at the most proximal part of the stent retriever or as to say the closest part of the stent retriever to the main catheter through which the coil would be removed.
While all published cases dealt with intracranial coils (Leslie-Mazwi et al. 2013; O'Hare et al. 2010; Liu et al. 2014; Hopf-Jensen et al. 2013; Kabbani et al. 2014) and only one case with a dislocated coil in the peroneal artery (Nikoubashman et al. 2015b), we have shown that retrieving dislocated coils in the abdominal vessels is also effective and this time using yet another available stent retriever (pRESET). To our knowledge is this case study the first one to deal with a coil dislocation in an abdominal vessel and the first one to use the pRESET stent retriever. In summary, endovascular coil recovery with stent retrievers can be considered an effective and safe treatment option in a wide range of retrieving foreign bodies in different body regions.
Another way to minimize the possibility of coils getting dislocated in the first place is to use detachable coils instead of pushable coils, due to the possibility in the former type to retract and reposition a dislocated coil as long as it is not detached from the pusher wire. The cost factor considering the expensive detachable coils might make this solution somewhat difficult to implement on a large scale.