A body drainage system (100) for draining fluid from a body cavity of a patient. The system (100) including a rotatable peristaltic pump mechanism, a housing (115) for housing at least a portion of the peristaltic pump mechanism, a flexible tube (120, 122, 124). The flexible tube (120, 122, 124) is provided with a first and a second clip (110, 112), the clips (110, 112) being arranged around the tube circumference and at a distance between each other in the longitudinal direction of the tube (120, 122, 124). A tube pump portion (122) of the tube (120, 122, 124) between the clips (110, 112) are intended to be placed in one way only at the peristaltic pump mechanism making it possible for the rotatable peristaltic mechanism to compress the tube pump portion (122) repeatedly such that pumping occurs in a desired direction only.
