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Gastrointestinal snares designed to position and tighten fine-gauge, flexible or semirigid, adjustable wire loops around a region of tissue through an endoscope for mechanical or electrosurgical resection and hemostasis. These devices typically consist of a hollow tubular structure (e.g., a cannula), with one or more adjustable wire loops (rings) that protrude at the working end. The snare is introduced in the upper or lower gastrointestinal tract through the working channel of a flexible endoscope (e.g., colonoscope, gastroscope); a mechanism at the proximal end (handle) controls how much wire extends out of the channel and the movement of the sliding (cutting) loop as the loop is withdrawn into the cannula. The snare loops are made of monofilament or braided wires that are attached at the proximal end to an electrosurgical (usually monopolar) unit that provides circulation of radio-frequency electric current between the isolated metal loop (i.e., acting as an active electrode) and an external neutral electrode to heat the tissues and facilitate resection and cauterization. Endoscopic gastrointestinal snares are used mainly for electrosurgical removal of polyps, tumors, and other abnormal tissue from the upper or lower gastrointestinal tract, but mechanical (cold) resection may be used for small polyps.
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