Anastomosis device with collapsible distal head element

A surgical instrument for bonding body tissue includes an instrument shank or shaft, a first tool element, a second tool element axially movable relative to the first tool element, and an annular sleeve-like cutting element. The second tool element includes a plurality of tool element members that are radially deflectable. The first and second tool elements are each equipped with at least one electrode. The second tool element includes a biasing member that biases the tool element members in a radially inward direction. A stop member is operable in a first position to hold the tool element members against the biasing force of the biasing member in which the tool element members assume a maximum outer diameter. The stop member is further operable in a second position to release the tool element members such that the tool element members can deflect radially inwardly and cut body tissue.