A system for occlusion of the lumen of blood vessel segments, the system comprising: a) a single lobed metallic expandable body (100,150) comprising: a distal region; a proximal region generally opposite the distal region; an intermediate region transitioning from the distal region to the proximal region; a center axis extending proximal-distal between the proximal region and distal region; and a wall extending generally continuously through the intermediate region from the distal region to the proximal region to define an exterior surface of the expandable body (100, 150) and an interior surface of the expandable body, the interior surface defining a central void of the expandable body; wherein the expandable body is configured to expand from a deliverable configuration to an expanded configuration; b) a delivery catheter (300,400) comprising: a longitudinally extending body comprising a proximal end and a distal end generally opposite the proximal end, the distal end of the delivery catheter (300,400) being operably coupled to the proximal region of the expandable body (100,150); c) wherein, when the expandable body (100,150) is in the deliverable configuration, the wall assumes a pleated configuration comprising a plurality of pleats folded over in a clockwise direction relative to the center axis or a counter-clockwise direction relative to the center axis to form a folded-over region of the expandable body; d) wherein the delivery catheter (300,400) includes a hollow cylindrical member that defines a lumen to allow for passage of a fluid medium from the proximal end of the delivery catheter (300,400) to the distal end of the delivery catheter (300,400) and into the central void of the expandable body (100,150); e) wherein the passage of a fluid medium from the proximal end of the delivery catheter (300,400) into the central void of the expandable body can result in expansion of the expandable body; f) wherein, when the expandable body (100,150) is in the expanded configuration, the plurality of pleats is not folded over; g) wherein, when the expandable body (100,150) is in the expanded configuration the expandable body (100,150) possesses sufficient strength to maintain itself in the expanded configuration in vivo under typical physiologic conditions within the lumen of blood vessel segments after separation from the delivery device where the pressure inside and outside the central void is the same or similar; and h) wherein no solid or semi-solid material or member, not derived from the patient, is required in the interior volume of the expandable body to at least assist in causing the expandable body to assume or maintain the expanded configuration after separation of the expanded expandable body and the delivery device. a) a single lobed metallic expandable body (100,150) comprising: a distal region; a proximal region generally opposite the distal region; an intermediate region transitioning from the distal region to the proximal region; a center axis extending proximal-distal between the proximal region and distal region; and a wall extending generally continuously through the intermediate region from the distal region to the proximal region to define an exterior surface of the expandable body (100, 150) and an interior surface of the expandable body, the interior surface defining a central void of the expandable body; wherein the expandable body is configured to expand from a deliverable configuration to an expanded configuration; b) a delivery catheter (300,400) comprising: a longitudinally extending body comprising a proximal end and a distal end generally opposite the proximal end, the distal end of the delivery catheter (300,400) being operably coupled to the proximal region of the expandable body (100,150); c) wherein, when the expandable body (100,150) is in the deliverable configuration, the wall assumes a pleated configuration comprising a plurality of pleats folded over in a clockwise direction relative to the center axis or a counter-clockwise direction relative to the center axis to form a folded-over region of the expandable body; d) wherein the delivery catheter (300,400) includes a hollow cylindrical member that defines a lumen to allow for passage of a fluid medium from the proximal end of the delivery catheter (300,400) to the distal end of the delivery catheter (300,400) and into the central void of the expandable body (100,150); e) wherein the passage of a fluid medium from the proximal end of the delivery catheter (300,400) into the central void of the expandable body can result in expansion of the expandable body; f) wherein, when the expandable body (100,150) is in the expanded configuration, the plurality of pleats is not folded over; g) wherein, when the expandable body (100,150) is in the expanded configuration the expandable body (100,150) possesses sufficient strength to maintain itself in the expanded configuration in vivo under typical physiologic conditions within the lumen of blood vessel segments after separation from the delivery device where the pressure inside and outside the central void is the same or similar; and h) wherein no solid or semi-solid material or member, not derived from the patient, is required in the interior volume of the expandable body to at least assist in causing the expandable body to assume or maintain the expanded configuration after separation of the expanded expandable body and the delivery device.