A medical device for performing ileostomies and/or jejunostomies, includes a tubular element defining a transit channel having a plurality of entry openings for the faeces, insertable inside the intestine of a patient, and an exit opening for the faeces, positionable outside the intestine. The tubular element includes a first section having the entry openings and a second section having the exit opening. First obstruction means is associated with the tubular element, insertable inside the intestine, and movable between tight and widened configurations. The entry openings are positioned upstream of the first obstruction means, the latter being placed between the first and the second sections. External retention means cooperate with the patient's body to block the position of the first obstruction means with respect to the body itself. Stiffening means are integrally associated with one another at respective extremities and prevent the first section from bending.