An exhaust-pressure-operated balloon catheter system which is a cross stream thrombectomy catheter, such as, but not limited to, an Angiojet(*) catheter with a flexible and expandable balloon, wherein the balloon is formed from and is continuous with the catheter tube which, in part, forms the cross stream thrombectomy catheter, wherein the balloon is deployable and expandable about the distal region of the cross stream thrombectomy catheter to act as an occluder device, and wherein the balloon is located proximal to the fluid jet emanator and inflow and outflow orifices upstream of ablative cross stream flows. The balloon is expandably deployed by the exhaust or back pressure created by the operation of the cross stream flows as generated by the fluid jets of the operating exhaust-pressure-operated balloon catheter system.