The medical device (1) for performing ileostomies and/or jejunostomies, comprises at least a tubular element (2) wherein is defined at least a transit channel (3) having a plurality of entry openings (3a) for the faeces, insertable inside the intestine (I) of a patient, and at least an exit opening (3b) for the faeces, positionable outside the intestine (I), where the tubular element (2) comprises at least a first section (2a) in which are obtained the entry openings (3a) and at least a second section (2b) in which is obtained the exit opening (3b), first obstruction means (5) of at least an area (Z) of the intestine (I) associated with the tubular element (2), insertable inside the intestine itself and movable between a tight configuration and a widened configuration, the entry openings (3a) being positionable upstream of the first obstruction means (5), the latter being placed between ihe first and the second sections (2a, 2b), external retention means (8) able to cooperate with the patients body to block the position of the first obstruction means (5) with respect to the body itself, stiffening means (17) associated with at least the first section (2a) to prevent it from bending and comprising a plurality of elastically deformable stiffening elements (17a), where the stiffening elements (17a) are integrally associated with one another at their respective extremities.