An apparatus is presented for use with a biologically- compatible- fluid pressure source. The apparatus comprises an elongated carrier (304) defining a fluid passagewayand adapted to be inserted through a proximal opening of a body lumen having a main axis and certain diameter; an inflatable balloon assembly (302) having an inflatable part self - def ormable between its substantially circular geometric state (321) and multiple elongated geometry states (322) in which cross sectional dimensions of the inflatable balloon part are different in accordance with the diameter of the lumen, and being in fluid communication with said fluid passageway, the cross sectional dimension of the substantially circular geometric state being equal to or greater than said diameter of said body lumen; and at least one sleeve (306) extending from at least one end respectively of said inflatable part of the balloon assembly along a central axis (318) of said inflatable balloon part, said at least one sleeve being by its one end is rigidly coupled to the respective end of the balloon part and having one of the following configurations: (a) being by its other end (310) fixed to the carrier at a certain location and being foldable and extendable in accordance with longitudinal deformation of the inflatable balloon part, and (b) having a fixed length and being by its other end slidable along the carrier in accordance with longitudinal deformation of the inflatable balloon part. Deformation of the inflatable part of the balloon maintains the balloon assembly orientation such that the carrier passing through the balloon assembly substantially coincides with said main axis of said lumen.
