Systems for removal of thrombus from a blood vessel in a body of a patient are disclosed. The system can include: a thrombus extraction device including a proximal selfexpanding coring element; a distal expandable element formed of a mesh structure having a proximal end portion attached to a distal end portion of the coring element; a catheter defining a lumen configured to constrain the thrombus extraction device; an intermediate shaft coupled to a proximal end portion of the coring element; an inner shaft coupled to a distal end portion of the expandable element and slidably displaceable relative to the intermediate shaft to control expansion of the expandable element; and an introducer sheath assembly including an elongate sheath defining an insertion lumen; an expandable funnel coupled to a distal end portion of the elongate sheath; and an elongate obturator including a capture feature configured to retain the funnel in a constrained configuration. In addition, an introducer sheath assembly is also disclosed herein.