Principles of rendezvous and retrieval procedures


Foreign body retrieval is almost exclusively reserved for iatrogenic problems, most of which will have been of your own making! The techniques and equipment described can also be used for snaring guidewires for pull-through procedures or to reposition misplaced central lines. The majority of foreign body retrieval is within the vascular system, although occasionally these techniques are required in the biliary or urinary system.

The toolkit

See essential equipment: snares ( Ch. 17 ).

There are not many tools at your disposal and, fortunately, most snares are simple to use, so a thorough understanding of the basic principles of how they work and an inventive mind are the keys to success.

Clinical scenarios

Removal of foreign bodies

The key decision is avoid the ‘ foreign body retrieval reflex ’; consider whether there is a good clinical reason for removing it. This requires an understanding of the likely impact of leaving it in situ; the risks associated with moving or removing it using endovascular techniques; and the risks of alternative strategies. Sometimes, a combined approach is best, e.g. a bullet free in the right atrium has the potential to cause considerable harm in addition to the havoc caused getting there in the first place. It could be removed by cardiothoracic surgery but a better solution may be to capture it with a snare and bring it back to the femoral artery. Clearly, it cannot be extracted safely through a normal sheath but it can be removed by surgical cutdown.

Stents, embolization coils and fragments of catheter and guidewire will probably cause vessel thrombosis. Only if thrombosis is likely to be clinically relevant should retrieval be attempted; if not, leave the foreign body where it is. If something does need to be removed, it is a good idea to heparinize the patient to prevent thrombosis during the procedure.

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