A device for resecting an organ in a cavity of a living body, in particular of a human being, includes a guide defining a duct opening out at both ends； two electrical conductors slidably mounted in the duct； an open loop made of a material that is electrically conductive and resistive in order to be suitable for producing heat by the Joule effect； elements for electrically connecting the two terminals respectively to the ends of the conductors； the loop being arranged so as to be suitable for taking on two states, namely a first state in which an orthogonal projection of its overall section onto a plane perpendicular to the longitudinal axes lies within the inside section of the duct as defined in the same plane, and a second state in which its overall section is greater than the inside section of the duct
