A catheter includes an elongated body and an expandable member configured to expand radially outward away from the elongated body from a collapsed configuration to an expanded configuration. The catheter further includes a retainer configured to overlap an end of the expandable member to hold the expandable member in the collapsed configuration. The expandable member may be configured to engage with a vessel wall when the expandable member is in the expanded configuration. The vessel may curve and the expandable member may be configured to deflect a portion of the elongated body distal to the expandable member when the expandable member is engaged with the vessel wall to better conform the shape of the elongated body to the curved portion of the vessel.