An irrigation/aspiration system for irrigating and aspirating a surgical site includes an irrigation flow path for directing fluid towards the surgical site via an irrigation connection, and an aspiration flow path for directing fluid away from the surgical site via an aspiration connection. A membrane pump is arranged for pumping fluid through the irrigation flow path and/or the aspiration flow path. The membrane pump includes a main pump chamber, at least two valves for opening and/or closing the main pump chamber and an auxiliary pump chamber arranged between the irrigation connection and/or aspiration connection and the main pump chamber for compensating movement of a main pump plunger element in the main pump chamber to provide for an approximately even fluid flow to and/or from the surgical site.