An apparatus for controlling a flow of sperms in a uterine tube formed by a uterine tube wall of a patient's uterine tube comprises an implantable constriction device for gently constricting {i.e. without substantially hampering the blood circulation in the uterine tube wall) at least one portion of the uterine tube wall to influence the flow in the uterine tube, and a stimulation device for stimulating the wall portion of the uterine tube wall. A control device controls the stimulation device to stimulate the wall portion, as the constriction device constricts the wall portion, to cause contraction of the wall portion constricted by the constriction device to further influence the flow in the uterine tube. The apparatus can be used for restricting or stopping the flow in the uterine tube, or for actively moving the fluid in the uterine tube, with a low risk of injuring the uterine tube.
