The present invention relates to devices for performing the resection of an organ in a cavity of a living body, in particular of a human being. The device according to the invention is essentially characterized in that it comprises a guide 10 defining a conduit 13, which is open at its two ends； two electrical conductors 21, 22 mounted slidably in the conduit； an open loop 40 made of an electrically conductive and resistant material so as to be able to produce heat by the Joule effect； means 30 for electrically connecting the two terminals 41, 42 to the ends 21-2, 22-2, respectively, of the conductors 21, 22, the loop 40 being designed to be able to adopt two states, namely a first state E1, in which the orthogonal projection of its overall cross section in a plane perpendicular to the longitudinal axes is included within the internal cross section of the conduit 13 defined in the same plane, and a second state, in which its overall cross section is larger than the internal cross section of the conduit 13.
