The invention comprises a surgical instrument including an external tube (2) and two elongated members (4) positioned in said tube (2), each of which includes a distal end (10a) for capturing one of the two tissue zones (M1, M2) to be attached. The instrument (1) may further comprise a catching member (22, 25) for each tissue (M1, M2) to be attached; a rod (15, 16) linked to each catching member (22, 25) enabling tension to move axially, said rod (15, 16) being separable from said catching member (22, 25) when a tension is exerted on it beyond a certain threshold; and a member (17a) forming a stop for locking axially each catching member (22, 25) during said tension.