Abstract: In an apparatus for medical treatments, examinations or tests comprising a hamber connectible to a vacuum source and having at its one end side a passage aperture with a flexible sealing member, the chamber is formed of a foldable bellow provided with a support structure adapted to be dismantled. In axial direction of the bellow, the support structure contains a plurality of substantially parallel-mounted peripheral members backing up peripherally the bellow and being mobile relative to each other, as well as mobile longitudinal stiffening elements secured to the peripheral members.