A cyclic opening flow regulator system (60) to prevent post-occlusion instability of a body cavity during surgical aspiration of fluid and tissue fragments through an aspiration opening of a surgical probe (80), comprising: a) a flow regulating valve part (64) defining a fluid opening (200) with adjustable cross-sectional area, said fluid opening being inserted into a fluid path connecting said aspiration opening of said surgical probe with a vacuum source, b) an actuator part (62) connected with said flow regulating valve part that can be operated to modify the cross-sectional area of said fluid opening (200), c) a controller (132) which provides a cyclic order signal to said actuator part to cause cycles of variation of the cross-sectional area of said fluid opening, each of which di at least one segment in which said cross-sectional area of said fluid opening is substantially reduced or closed, said cycles being produced at a frequency high enough to produce a flow that is substantially stable in said suction opening of said probe surgical, whereby said fluid and said tissue fragments (204) can be aspirated from said body cavity using said surgical probe along said fluid path without causing instability of said body cavity caused by sudden increases in fluid within said fluid path caused by the occlusion breaks of said suction opening of said surgical probe, characterized in that the flow regulating valve comprises a valve rotor (290) adapted to rotate and to be able to move slidably and axial in a valve chamber (292), and why the reg valve part flow ulation (64) defining a fluid opening (200) with adjustable cross-sectional area, said fluid opening being inserted in a fluid path (172) connecting said aspiration opening of said surgical probe with a source of vacuum, comprises a rotor cover (294) defining said fluid opening (200), in which the valve rotor (290) moves axially within the valve chamber (292) during rotation to modify the area of cross section of sai
