The invention relates to a catheter, in particular a balloon catheter, having a fluid-carrying element, such as a drainage tube, with an inner lumen for carrying away body fluid, and having an expansion element, such as a balloon of variable cross section, for fixing the catheter in a body cavity. The fluid-carrying element has a wall portion of an open-pore material, which is in fluidic communication with the inner lumen and through which the body fluid can be aspirated into the inner lumen by applying a negative pressure to a proximal end of the fluid-carrying element. The invention furthermore relates to a catheter system having a catheter of the invention and to a vacuum-generating system connected to the catheter.
